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  • Articles  (55,160)
  • 1995-1999  (24,027)
  • 1975-1979  (15,884)
  • 1970-1974  (15,249)
  • Process Engineering, Biotechnology, Nutrition Technology  (55,160)
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  • Articles  (55,160)
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  • 1
    ISSN: 1431-4630
    Keywords: Key words Photoacoustic spectroscopy in visible light ; Reflectance spectroscopy in visible light ; Skimmed milk powder ; Whey powder ; Adulteration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  A novel methodology is proposed to determine the amount of whey powder in a binary mixture containing whey and skimmed-milk powders. This new approach is based on measurement of the amplitude of the photoacoustic (PA) signal obtained when the mixture is exposed to a controlled thermal treatment; the latter was shown to affect the colour of the powder. The limit of detection for the whey powder adulterant was 2% by weight. The PA and reflectance spectra (in the visible region) of the mixtures were also compared.
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  • 2
    ISSN: 1431-4630
    Keywords: Key words White pan bread ; Staling ; Gluten ; Firmness ; Storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Continuing an investigation into the different factors affecting the quality of white pan bread and the changes taking place during storage, on the basis of instrumental determinations of firmness using compression and bending tests, this second instalment addresses the influence of adding gluten to the dough. Three types of bread were prepared using three different water contents and three proportions of added gluten each. Firmness was evaluated at 24, 48 and 72 h. Addition of gluten significantly increased flexibility and significantly decreased firmness in the bread at the higher water content levels. It also improved the keeping properties of the bread by slowing the increase in firmness with time; this effect was also higher at the higher water content levels.
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  • 3
    ISSN: 1431-4630
    Keywords: Key words Behenic acid tryptamide ; Lignocerinic acid tryptamide ; Electrospray mass spectrometry ; Chocolate ; Cocoa products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Tetracosanoyl-2-(3-indolyl)ethane amide (lignocerinic acid tryptamide; LAT) and docosanoyl-2-(3-indolyl)ethane amide (behenic acid tryptamide; BAT) were identified as the most prominent tryptamides in cocoa shells based on electrospray ionisation mass spectrometry and 1H NMR measurements. The structure of LAT, which is reported for the first time in cocoa shells, and also that of BAT were confirmed by synthesis. By using synthesised heptadecanoyl-2-(3-indolyl)ethane amide as the internal standard, a sensitive and reproducible method was developed for the quantification of LAT and BAT in the picogram range by means of HPLC/fluorescence detection. The detection limit was determined to be 30 pg/run. In authentic shell samples, 50-fold higher concentrations of both tryptamides were determined compared to the cocoa cotyledons. In 15 commercial chocolate samples, concentrations of 23.1–63.0 μg of the tryptamides (sum of both) per gram of fat were found. A first experiment attempted to correlate the tryptamide content with the amounts of shells in a model chocolate showed that the method is a promising tool to determine the shell content in the quality assessment of cocoa products.
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  • 4
    ISSN: 1431-4630
    Keywords: Key words Kola nut ; Botryodiplodia theobromae ; Fusarium pallidoroseum ; Storage mould ; Pre-storage treatments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The effect of curing kola nuts at 30  °C was evaluated at the Cocoa Research Institute of Nigeria, Ibadan, to determine the effect of curing time and delay between inoculation and initiation of curing on storage rot. For nuts inoculated 24 h prior to curing, 48–72 h curing at 30  °C gave optimal disease control. The incidence of rot was higher when the treatment was delayed for 48 h after inoculation. When artificially wounded and inoculated kola nuts were dipped in a solution of 1.0 g l–1 of sodium bicarbonate for 2 mins, disease development was significantly reduced compared to the 0.5% sodium hypochorite treatment. Sodium metabisulphite also reduced disease development but the level of disease control achieved was not significantly different from that of the water-dipped controls. The in vivo results were consistent with the in vitro results.
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  • 5
    ISSN: 1431-4630
    Keywords: Key words Flavor enhancer ; Savory flavoring ; Taste ; Amino acids ; Partial least squares regression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Enzymatically hydrolyzed vegetable protein was produced from soy protein using hydrolysis times of 0–20 h. The development of sensory properties and the pattern of protein degradation was followed. Around two-thirds of the final amount of free amino acids and degree of hydrolysis (DH) were achieved during the first 4 h of hydrolysis. Between 6 h and 10 h of hydrolysis the bouillon-like tastes increased significantly (P〈0.001). In this time interval the amount of free amino acids exceeded 40% of the total amino acids and the DH exceeded 50% of the theoretically possible (100%). Using partial least squares regression with standardisation of free amino acid data according to their taste threshold values showed that free glutamic acid, aspartic acid and lysine correlated with the bouillon-like tastes. By standardisation of free amino acid data with respect to their SD the specificity of the enzymes for amino acid side-chains could be seen.
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  • 6
    ISSN: 1431-4630
    Keywords: Key words Bifidobacterium ; Soya milk ; Oligosaccharides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The reduction of soya milk oligosaccharides by Bifidobacterium longum CRL 849 was studied. The utilization of stachyose was concomitant with the use of sucrose. Maximum hydrolysis of stachyose (49.3%) occurred during the first 7 h of incubation at 37  °C, while a 79.3% decrease in the concentration of sucrose was observed after 9 h. No raffinose was detected after hydrolysis of the stachyose. Cell population decreased after 8 h of incubation because of the low pH attained (pH 4.7). l(+)-Lactate concentration was higher than acetate (molar ratio 6.7 : 1) at 6 h followed by a slow increase in acetate formation. Ethanol was detected in small amounts at the end of the incubation time (24 h).
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  • 7
    ISSN: 1431-4630
    Keywords: Key words Dioctyl adipate ; Acetyltributyl citrate ; Plasticizers ; Migration ; Microwave heating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Migration of dioctyl adipate (DOA) and acetyltributyl citrate (ATBC) plasticizers from plasticized poly(vinyl chloride) and poly(vinylidene chloride/vinyl chloride) films into ground meat of varying fat content (3%, 12%, 30%, 55%) during microwave heating has been studied. The plasticizer migrating into ground meat was determined using an indirect gas chromatographic method after saponification of the ester-type plasticizer (DOA or ATBC) and subsequent collection of the alcohol component of the ester, namely 2-ethyl-1-hexanol and 1-butanol, respectively. Identical unwrapped microwave heated (control) samples were also analysed for DOA and ATBC content. Migration was dependent on heating time, fat content of the meat and the initial concentration of the plasticizer in the film. Migration of DOA and ATBC into ground meat did not reach equilibrium after heating for 4 min at full power even for meat samples of high fat content (55%). Migration values of DOA and ATBC into ground meat of 55% fat content after 4 min of heating in a microwave oven were 172.39 mg/kg (14.62 mg/dm2) and 17.24 mg/kg (0.62 mg/dm2), respectively. Migration into control samples was below the detection limit of the method employed (〈2 mg/kg for DOA and 〈2.5 mg/kg for ATBC).
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  • 8
    ISSN: 1431-4630
    Keywords: Key words Porcine β-casein ; Bovine β-casein ; Hydrolysts ; Bovine plasmin ; Bovine chymosin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The action of bovine chymosin and bovine plasmin on porcine β-casein was studied and compared with their effect on bovine β-casein in an attempt to elucidate the similarities in specificity of these enzymes on porcine and bovine β-caseins. Bovine plasmin rapidly hydrolysed porcine β-casein at Lys106-Arg107, Lys49-Ile50 and Lys168-Val169 to yield γ-caseins. Several peptides that had the same N-terminal amino acid sequence as porcine β-casein were also produced. Plasmin hydrolysis sites determined by separating the pH 4.6-soluble peptides formed on hydrolysis were Lys33-Leu34, Lys49-Ile50, Lys95-Asp96, Lys98-Ala99, Lys106-Arg107, Lys108-Gly109 and Lys168-Val169. Porcine β-casein, like bovine β-casein, was hydrolysed by bovine chymosin into three distinct electrophoretic bands designated porcine β-I-, β-II- and β-III-casein, all of which had the N-terminal sequence of porcine β-casein. Two initial pH 4.6-soluble peptides formed on hydrolysis of porcine β-casein by chymosin had N-terminal amino acid sequences commencing at porcine β-casein amino acid 197, suggesting that porcine β-I-casein corresponds to fragment 1–196, while the sequences of two other small peptides commenced at amino acids 1 and 207. The C-terminal cleavage site(s) leading to formation of porcine β-II and β-III casein were not determined.
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  • 9
    ISSN: 1431-4630
    Keywords: Key words Lead ; Cadmium ; Meat ; Domestic animals ; Atomic absorption spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Levels of lead and cadmium were determined in tissues of muscle, liver and kidney from horse, lamb, sheep and reindeer in Sweden during the years 1994–1997. Mean levels of lead in muscle, liver and kidney from horse were 〈0.002, 0.13 and 0.047, from lamb 〈0.002, 0.031 and 0.053, from sheep 〈0.002, not analysed and 0.046, and from reindeer 0.003, 0.13 and 0.13 mg/fresh weight, respectively. The mean levels of cadmium in muscle, liver and kidney from horse were 0.042, 2.5 and 18, from lamb 0.0019, 0.031 and 0.12, from sheep 0.0034, not analysed and 1.0, and from reindeer 0.003, 0.60 and 2.7 mg/fresh weight, respectively. Comparisons with literature data were attempted. In some cases the results could differ by several orders of magnitude. It cannot be ruled out that some of the differences between studies might be due to analytical differences, making comparisons very difficult.
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  • 10
    ISSN: 1431-4630
    Keywords: Key words Nisin ; Lactic acid ; Cold smoking ; Microbiological quality ; Sensory quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The effect of lactic acid and nisin whey permeate on the microbiological and sensory quality of cold-smoked rainbow trout was studied. Lactic acid and whey permeate were mixed with salt solution and injected into fish fillets in concentrations of up to 2.5 g/kg lactic acid, 30 g/kg whey permeate and 20 g/kg sodium chloride. After smoking at 28  °C for 6 h the fillets were sliced, vacuum packed and stored at 3  °C. The aerobic and anaerobic/facultative anaerobic counts were measured after 1, 8, 15, 22 and 29 days of storage. The influence of the treatment on the sensory characteristics was analysed after 8 and 22 days by sensory profiling. A triangle test was used in order to ascertain at which stage the sensory quality of the samples changed during storage. Bacterial counts of smoked fish stored for 29 days were lowest in those samples containing a combination of lactic acid, sodium chloride and nisin whey permeate. Lactic acid alone did not affect the odour or flavour characteristics of the fish but did affect their texture as determined by sensory evaluation making it less elastic when stored at +3  °C for 8 days. A combination of lactic acid and nisin whey permeate enhanced the characteristic fishy flavour of the product. Differences between treatments in elasticity and fishy flavour were not detected after 22 days of storage. According to the triangle test, the samples from all treatments remained unchanged over the first 15 days.
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  • 11
    ISSN: 1431-4630
    Keywords: Key words Ascorbic acid ; High-temperature short-time degradation ; Thermoresistometer ; Green asparagus ; Kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Thermal degradation of green asparagus ascorbic acid in high-temperature short-time conditions was studied by heating in a five-channel computer-controlled thermoresistometer. Ascorbic acid was heated to between 110  °C and 140  °C and the degradation kinetics were analyzed assuming that two different inactivation mechanisms were occurring, one aerobic and the other anaerobic. The two reactions followed first-order kinetics, with E a=12.3(2.0) kcal/mol and k 125  °C=47.0(3.0)×10–3 s–1 for the aerobic oxidation, and E a=6.1(1.4) kcal/mol and k 125  °C=4.1(0.2)×10–3 s–1 for the anaerobic degradation.
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  • 12
    ISSN: 1431-4630
    Keywords: Key words Bagaceira ; Grape pomace ; Distillation ; Volatiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The effects of fermentation time and distillation cuts on the composition of distillates in terms of ethanal, 1,1-diethoxyethane, methanol, 1-butanol, 2-butanol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl acetate, ethyl 2-hydroxypropanoate, 3-methylbutyl acetate, hexyl acetate, 2-phenylethyl acetate, hexanol, trans-2-hexenol, trans-3-hexenol, cis-3-hexenol, 2-phenylethanol, ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl dodecanoate, 2-methylpropanoic acid, 3-methylbutanoic acid, hexanoic acid, octanoic acid, decanoic acid, and dodecanoic acid were assessed through data generated according to a factorial design using analysis of variance and principal component analysis. Four times of storage of pomace obtained following winemaking of two grape varieties of white Verde wine (Alvarinho and Loureiro) and three distillation cuts were considered; volatile compounds in the 24 samples generated were analyzed directly, and indirectly after extraction and concentration, by capillary gas chromatography. The results generated have suggested clear differences (P〈0.05) between distillate cuts obtained throughout fermentation times for each grape variety. The major differences between the different distillate fractions analyzed were accounted for by the contents of diethyl butanoate, ethyl 2-hydroxypropanoate, and the sum of 3-methylbutanoic and 2-methylpropanoic acids for Loureiro, whereas the main differences were accounted for by the contents of diethyl butanoate and the sum of the carboxylic acids for Alvarinho.
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  • 13
    ISSN: 1431-4630
    Keywords: Key words Capillary electrophoresis ; Carbohydrates ; Enantiomers ; D/L-Sugars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  A method for the analysis of reducing sugar enantiomers in beverages using capillary zone electrophoresis is presented. Based on previous results, a resolution of all aldo-hexoses, -pentoses, -tetroses and trioses is achieved. Additional separation of uronic acids, deoxy and amino sugars in different buffer systems is demonstrated. Derivatives of sugar enantiomers change their migration order if derivatized with the phenylethylamine enantiomer. Thus, the use of a chiral derivatizing agent leads to simpler peak validation and opens new opportunities for the development of new applications. Screening of pharmaceutical drugs or food for rare sugar enantiomers with a detection limit of 25 fmol (5 μM) is feasible. Adaptation of the general method to wine, juice and instant coffee is demonstrated. The aldose, uronic acid and deoxy aldose enantiomer composition of the presented beverages is obtained in a single run.
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  • 14
    ISSN: 1431-4630
    Keywords: Key words Thermal indices ; Pasteurized milks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Lactoperoxidase activity and lactulose, furosine and undenatured whey protein contents were determined in Spanish commercial milks labelled as pasteurized (group A) and high-temperature pasteurized (group B), in order to assess their quality. Three samples of group A and all of the samples of group B were lactoperoxidase negative. Most samples of group A had measurable amounts of lactulose, even though their concentrations of undenatured β-lactoglobulin were higher than 2600 mg/l. In general, samples of group B showed higher lactulose and furosine and lower undenatured whey protein contents. High levels of furosine and lactulose accompanied by high levels of undenatured β-lactoglobulin could indicate the addition of milk heated at high temperatures, whereas high levels of furosine and relatively low levels of lactulose may have been due to the presence of reconstituted milk powder.
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  • 15
    ISSN: 1431-4630
    Keywords: Key words BADGE ; Bisphenol A diglycidyl ether ; Bisphenol A bis(2 ; 3-dihydroxypropyl) ether ; HPLC ; Epoxy resins ; Canned food
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Bisphenol A diglycidyl ether (BADGE) is determined in canned oily foods from Austria using a new simplified HPLC method. Samples are extracted with pentane, back extracted with methanol, and finally dissolved in the mobile phase (cyclohexane/tert–butyl methyl ether). Separation is performed on a normal-phase HPLC column using fluorescence detection. Verification of the BADGE-containing peak is carried out by using off-line GC-MS. Additionally, the synthesis and determination of BADGE hydrolysis products, Bisphenol A bis(2,3-dihydroxypropyl) ether (BADGE.2H2O) and Bisphenol A glycidyl (2,3-dihydroxypropyl) ether (BADGE.H2O) are presented. From 67 analyzed cans, containing various fatty meat or fish products, 16% were above the maximum quantity of 1 mg/kg tolerated by the European Community, 45% were in the range between 0.1–1 mg/kg, 24% between 0.02 and 0.1 mg/kg, and in 15% the BADGE concentrations were below the detection limit of 0.02 mg/kg. The hydrolysis product BADGE.H2O was not detected in any sample, whereas BADGE.2H2O was found in some samples up to a concentration of 0.5 mg/kg.
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  • 16
    ISSN: 1431-4630
    Keywords: Key words Pasta colour ; Yellow pigment ; Spectrophotometry ; Colorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Product colour is one of the most important criteria for determining pasta quality. For pasta produced without eggs, pasta colour will depend mostly on the content of the yellow pigment in flour. Analyses were done with 12 samples of hand-made pasta without eggs. The yellow pigment content was determined by the standard spectrophotometric method, while the pasta colour (fresh shaped and dry milled pasta) was measured using the Minolta CR-300 colorimeter. The results obtained show that there is a correlation between spectrophotometric determination of the yellow pigment content and the results of colorimetric measurement. The correlation coefficient between the colorimetric results of dry milled pasta and the yellow pigment content is higher than that between the colorimetric results of fresh shaped pasta and the yellow pigment content.
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  • 17
    ISSN: 1431-4630
    Keywords: Key words White pan bread ; Enzymes ; Staling ; Firmness ; Elasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Several different types of enzymes and their blends were added to dough with the object of improving the shelf-life of white, lidded-pan bread during storage. Bread firmness and elasticity were determined at 24, 48 and 72 h to determine the influence of the enzymes. Addition of bacterial a-amylase, specially to blends of enzymes also containing lipase and pentosanase, improved white, lidded-pan bread quality by increasing elasticity and lowering firmness of crumb, and enhanced the keeping quality over time by providing a significant 2-day increase in the shelf life.
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  • 18
    ISSN: 1431-4630
    Keywords: Key words Alcoholic beverages ; Principal component analysis ; Whisky ; Rum ; Brandy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract   The aim was to achieve a simple method or methods by which different countries' and regions' brands of whisky, brandy and rum could be identified on the basis of chemical composition, ultraviolet-visible (UV-vis) absorption, and/or pH. The analytical results were processed statistically using principal components analysis. To determine whether the concentrations of chemical components in a particular brand remain constant, samples of batches bottled over a period of 3–4 years and those bottled within the same year were compared. In study 1 (14 whiskies, 7 rums and 9 brandies) the main distinguishing factors among the three categories of beverages were the UV-vis absorbances at 220, 275, 360 and 440 nm, concentrations of four fermentation alcohols and ethyl acetate, and pH. In study 2 (27 whiskies and 2 rums), brands could be identified on the basis of the concentrations of five fermentation alcohols and ethyl acetate. Even though it was possible to distinguish brandy from whisky and rum without quantitative component analysis, whisky and rum clusters could not be clearly separated from each other or by brand on the basis of pH and absorbances at discrete wavelengths. UV spectra of whiskies, rums, and brandies were recorded and compared statistically. Whisky brands could not be differentiated but it was possible to distinguish among brands of rum and brandy.
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  • 19
    ISSN: 1431-4630
    Keywords: Key words Dioctyl adipate ; Acetyltributyl citrate ; Plasticizers ; Microwave heating ; Migration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The effect of microwave heating versus conventional heating on the migration of dioctyl adipate (DOA) and acetyltributyl citrate (ATBC) plasticizers from plasticized poly(vinyl chloride) (PVC) and poly(vinylidene chloride/vinyl chloride) (P[VDC/VC]) films into pizza and frankfurter-type sausages has been studied. Microwave heating was carried out with and without a susceptor. The plasticizer migrating into the food was determined using an indirect gas chromatographic method after saponification of the ester-type plasticizer (DOA or ATBC) and subsequent collection of the alcoholic component of the ester, namely 2-ethyl-1-hexanol and 1-butanol, respectively. The extent of migration of both plasticizers into pizza and sausage followed the sequence: heating in conventional oven 〉 microwave heating with a susceptor 〉 microwave heating without a susceptor. The amounts of DOA that migrated into pizza and sausage were 105.12 mg/kg and 85.01 mg/kg during conventional heating, 75.52 mg/kg and 47.69 mg/kg during microwave heating with a susceptor and 51.42 mg/kg and 37.98 mg/kg during microwave heating without a susceptor, respectively. The amounts of ATBC that migrated into pizza and sausage were 31.18 mg/kg and 25.37 mg/kg during conventional heating, 7.73 mg/kg and 7.02 mg/kg during microwave heating with a susceptor and 6.25 mg/kg and 5.17 mg/kg during microwave heating without a susceptor.
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  • 20
    ISSN: 1431-4630
    Keywords: Key words Saccharomyces cerevisiae ; Fragile mutant ; Nutritional protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Saccharomyces cerevisiae 211 is a fragile yeast mutant whose cells grow only in media supplemented with osmotic stabilizer (1.6% NaCl), but which lyse spontaneously in water. This property provides a non-conventional way for isolation of nutritional protein and other products. We describe here a procedure based on the lysis ability of fragile yeasts for processing the biomass into several fractions. Cell lysis and downstream fractionation of the lysate do not include chemical or temperature treatment steps. The obtained protein fractions account for half of the starting biomass and contain 86% fully digestible protein and only 2% nucleic acids. The glycan fraction (with 83% polysaccharides) and the low molecular mass fraction are by-products of the procedure. The latter can be used as a nutritional media supplement in microbiology and as a source for purification of 5′-GMP, a potent flavour enhancer. The high rate of quantitative recovery and the mild conditions used to fractionate the biomass indicate the advantages of the fragile yeasts for production of nutritional protein and other products on a large scale by an efficient and non-wasteful technology.
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  • 21
    ISSN: 1431-4630
    Keywords: Key words Biscuits ; Microencapsulation ; High-fat powder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Effects of microencapsulated high-fat powders in the substitution of butter or margarine in block form on production properties and final product characteristics of semi-sweet, short dough biscuits were studied. Dough hardness was largely affected by the type of fat used, whereas higher protein concentrations in powders had a positive effect on the sheeting behaviour of the dough. Biscuits containing fat in encapsulated form developed a darker colour following the same baking conditions as for the standard products. Colour development was positively correlated to water activity levels in the biscuits. The addition of certain powders led to the production of thinner biscuits, which also appeared to be undesirably hard as measured during a snap test.
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  • 22
    ISSN: 1431-4630
    Keywords: Key words Wine ; Oxygen isotopes ; Adulteration control ; Origin assignment ; European Union data bank
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The application of oxygen isotope analysis to wine water (according to EU regulation no. 822/97) to determine a wine's origin, and check that it has not been adulterated is gaining increasing importance in both laboratories and industry. Using samples of Italian, French and German wines from the EU wine data bank (EU-DB), good agreement between the results from participating laboratories was demonstrated. Close correlations between the oxygen isotope contents of must and related wine water were found for samples from all countries. Based on the results of the δ18O values for EU-DB wines from 1991 to 1996 from Italy, France and Germany, we describe and discuss the main factors which are responsible for the variation of the oxygen isotope ratios of wine water. The examination of spiked samples demonstrated the usefulness of δ18O analysis for the detection of the watering down of wine. The possibility of origin assignment, preferably if the determination of the δ18O value by isotope ratio mass spectrometry (IRMS) is employed together with the determination of the site-specific hydrogen isotope content of wine ethanol by 2H-NMR and the measurement of δ13C values of ethanol by IRMS, is outlined.
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  • 23
    ISSN: 1431-4630
    Keywords: Key words Amino acid epimerization ; Infant formulae ; Food proteins ; Hydroxyproline stereoisomers ; Gas chromatography-mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Aqueous solutions (5 g/100 ml) of commercial preparations of (a) an enzymatic partial hydrolysate of gelatin and (b) type A gelatin were subjected to threefold heating to boiling in a domestic microwave oven at 750 W and to conventional heating. Then samples were totally hydrolyzed (6 M hydrochloric acid, 110  °C, 24 h) and investigated for the presence of eight possible stereoisomers of 3- and 4-hydroxyproline (Hyp) using capillary gas chromatography. Amino acids were analyzed as N(O)-trifluoroacetyl 2-propyl esters on Chirasil-l-Val and detected by selected ion monitoring mass spectrometry. Blanks of (a) and (b) were analyzed in parallel. Relative amounts of 5.0±0.2% cis-4-d-Hyp were generated from native trans-4-l-Hyp as a result of total hydrolysis in all samples and independent of previous treatment. Notably, neither cis-3-l-Hyp nor cis-4-l-Hyp could be detected in either of the gelatin samples. Thus a report on the generation of antifibrotic and therefore potentially hazardous cis-3-l-Hyp and cis-4-l-Hyp from protein-bonded native trans-3-l-Hyp and trans-4-l-Hyp on microwave heating of infant formulae could not be confirmed.
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  • 24
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract For several years it has been known that fungi and bacteria can attack and even liquefy low rank coals. This review covers the progress in coal biotechnology and microbiology, mainly during the last decade, from describing the first effects to elucidating the mechanisms used by the microorganisms. More than one mechanism is responsible for microbial coal degradation/liquefaction: oxidative enzymes (peroxidases, laccases), hydrolytic enzymes (esterases), alkaline metabolites and natural chelators. Due to the heterogeneous structure of coal, which is described in one section, and for economic reasons the review focuses on the enzymatic depolymerization of brown coal. Approaches which seem not so promising are discussed (anaerobic, reductive pathways, chemical pretreatment). Finally the possible applications and products in this field are summarized, as lignite with a worldwide production of about 940 million tons a year will continue to play an important economic role in the future.
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  • 25
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Several fundamental aspects of microbial coal liquefaction/solubilization were studied. The liquefied/solubilized products from coal by microorganisms were analysed. The liquid products analysed by IR titration and UV/visible spectrometry showed some alterations with regard to the original coal. Humic acids extracted from the liquefied lignite showed a reduction in the average molecular weight and a increase in the condensation index, probably due to depolymerization caused by microorganisms. The mechanisms implicated in coal biosolubilization by two fungal strains, M2 (Trichoderma sp.) and M4 (Penicillium sp.) were also studied. Extracellular peroxidase, esterase and phenoloxidase enzymes appear to be involved in coal solubilization.
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  • 26
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Lignite (brown coal) can be liquefied/solubilized with several fungi by different mechanisms. When applied industrially, only catalytic mechanisms can compete with chemical methods. The well-known fungal ligninolytic peroxidases are at a disadvantage, in that the relatively expensive hydrogen peroxide must be used as a cofactor. Comparing several fungal strains, we observed that the fungus Trametes versicolor is able to decolorize coal-derived humic acids, producing a considerable amount of laccase in the process. During this reaction the amount of humic acids decreases whilst that of fulvic acids increases; this was verified by optical density measurement and GPC after the two substance classes had been separated.
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  • 27
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Three different mechanisms can be envisaged that are used by fungi to solubilize coal: the production of alkaline substances, the extrusion of chelators and, of special interest in the scope of biotechnology, the action of enzymes. Whether these mechanisms are operating separately or in various combinations has not yet been finally assessed. The two deuteromycetes Fusarium oxysporum and Trichoderma atroviride solubilize coal by synergistic effects of various different mechanisms depending on the cell metabolism. F. oxysporum seems to solubilize coal by increasing the pH of the mycelial surroundings and by the action of chelators induced during growth in glutamate-containing media (without involvement of enzymes). T. atroviride, on the other hand, appears to use, in addition to an alkaline pH and a high chelator activity, at least two classes of enzyme activity to attack coal: hydrolytic activity for coal solubilization and ligninolytic activity for degradation of humic acids.
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  • 28
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The majority of lignin-degrading basidiomycetes are able to depolymerize humic acids. In this presentation the relationship and possible similarities between enzymes involved in lignin degradation and humic acid depolymerization were examined on the genetic level. We have cloned fragments of the gene encoding the extracellular ligninolytic enzyme laccase from Clitocybula dusenii, Nematoloma frowardii and a fungal strain designated i63-2, and compared the three sequences with those of several other published laccase genes. The sequenced fragments displayed a high homology both on the DNA (97%–77%) and amino acid (100%–85%) level. Furthermore, the expression of this gene in the above-mentioned fungi was demonstrated by a nested polymerase chain reaction with cDNA as template.
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  • 29
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Indirect evidence has suggested that lignin peroxidase (LiP) of the white-rot fungus Phanerochaete chrysosporium catalyses oxidative decolourisation and depolymerisation of macromolecules from brown coal in vivo. In this study we show that LiP catalyses these transformations in vitro. Unmethylated (USC45 coal) and methylated (MWSC6 coal) fractions of solubilised macromolecules (M r 〉 30 000) from a brown coal were treated with a semi-purified preparation of LiP isozymes from P. chrysosporium. Both coal fractions were decolourised, losing between 26% and 39% of their absorbance at both 280 nm and 400 nm, in reactions that had an absolute requirement for H2O2 and veratryl alcohol. Neither coal fraction was transformed when the enzyme was heat-inactivated or in the presence of the LiP inhibitor metavanadate. Gel-permeation chromatography showed that MWSC6 coal but not USC45 was depolymerised and yielded low-molecular-mass (M r 〈 30 000) fragments. Nine monomeric products were identified by GC-MS.
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  • 30
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A screening identified several bacteria that were able to use chemically heterogeneous low-rank coal liquefaction products as complex carbon sources for growth. Pseudomonas oleovorans and Rhodococcus ruber accumulated polyhydroxyalkanoic acids (PHA) amounting to 2%–8% of the cell dry weight when the cells were cultivated on these liquefaction products in the absence of any other carbon source. R. ruber accumulated, in addition to PHA, small amounts of triacylglycerols. The accumulated PHA consisted of 3-hydroxyhexanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate (P. oleovorans) or 3-hydroxybutyric acid and 3-hydroxyvaleric acid (R. ruber). Low-rank coal liquefaction products obtained from Trichoderma atroviride were better substrates for P. oleovorans than chemically produced fulvic acids.
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  • 31
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Ligninolytic basidiomycetes (wood and leaf-litter-decaying fungi) have the ability to degrade low-rank coal (lignite). Extracellular manganese peroxidase is the crucial enzyme in the depolymerization process of both coal-derived humic substances and native coal. The depolymerization of coal by Mn peroxidase is catalysed via chelated Mn(III) acting as a diffusible mediator with a high redox potential and can be enhanced in the presence of additional mediating agents (e.g. glutathione). The depolymerization process results in the formation of a complex mixture of lower-molecular-mass fulvic-acid-like compounds. Experiments using a synthetic 14C-labeled humic acid demonstrated that the Mn peroxidase-catalyzed depolymerization of humic substances was accompanied by a substantial release of carbon dioxide (17%–50% of the initially added radioactivity was released as 14CO2). Mn peroxidase was found to be a highly stable enzyme that remained active for several weeks under reaction conditions in a liquid reaction mixture and even persisted in sterile and native soil from an opencast mining area for some days.
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  • 32
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The present work describes investigations on the bacterial degradation of the alicyclic molecule cyclododecane. It represents a structure where the initial degradative steps have to be similar to a “subterminal” attack as there is no “terminal” part of the molecule. We were able to show that the gram-positive bacterium Rhodococcus ruber CD4 DSM 44394 oxidizes cyclododecane to the corresponding alcohol and ketone, the latter being subject to ring fission by a Baeyer-Villiger oxygenase. This key enzyme is an NADPH- and O2-dependent flavoprotein with a substrate specificity for bigger rings. The further metabolism of the resulting lactone gives rise to an ω-hydroxyalkanoic acid that is susceptible to common β-oxidation. Due to its alicyclic character and its ring size, cyclododecane is comparable to aliphatic bridge components that are an important element in the coal texture. They contribute to the three-dimensional coal structure and thus could serve as a valuable target for the oxidative abilities of R. ruber CD4 to reduce the molecular mass of coal.
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  • 33
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A comparison of iron-sulfur proteins obtained from Thiobacillus ferrooxidans was carried out. The microorganisms were grown on iron(II)- or sulfur-containing nutrients. In both cases different, broad elctron paramagnetic resonance (EPR) lines, originating from an iron(III) compound, were detected. Additional EPR lines of tetrahedral iron(III) and free radicals were observed. The UV spectra of these compounds also differ.
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  • 34
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Two coals of different rank, mined in Russia, were treated by an anaerobic methanogenic enrichment culture. The addition of alkaline enclosing rock to the lower-rank coal increased the pH of the incubation medium and methane production above that of the higher-rank coal with addition of its enclosing rock. This effect was accompanied by the leaching of cations from the incubation medium. The coal was processed without a preliminary chemical treatment in a two-stage aerobic/anaerobic bioreactor containing an anaerobic methanogenic granulated enrichment culture.
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  • 35
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Accumulation of elemental sulfur during pyrite oxidation lowers the efficiency of coal desulfurization and bioleaching. In the case of pyrite bioleaching by Leptospirillum ferrooxidans, an iron(II)-ion-oxidizing organism without sulfur-oxidizing capacity, from the pyritic sulfur moiety about 10% elemental sulfur, 2% pentathionate, and 1% tetrathionate accumulated by a recently described cyclic pyrite oxidation mechanism. In the case of pure cultures of Thiobacillus ferrooxidans and mixed cultures of L. ferrooxidans and T. thiooxidans, pyrite was nearly completely oxidized to sulfate because of the capacity of these cultures to oxidize both iron(II) ions and sulfur compounds. Pyrite oxidation in acidic solutions, mediated chemically by iron(III) ion, resulted in an accumulation of similar amounts of sulfur compounds as obtained with L. ferrooxidans. Changes of pH to values below 2 or in the iron ion concentration are not decisive for diverting the flux of sulfur compounds. The literature on pyrite bioleaching is in agreement with the findings indicating that the chemistry of direct and indirect pyrite leaching is identical.
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  • 36
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Biocatalytic desulfurization is still not a commercial technology, but conceptual engineering and sensitivity analyses have shown that the approach is very promising. The purpose of this paper is to investigate further some aspects of the biodesulphurization pathways, discussing the non-destructive pathway with the well-known Rhodococcus rhodochrous IGTS8. Findings revealed byproducts, such as 2′-hydroxybiphenyl (HBP), sulfite and sulfate, obtained by the desulfurization of dibenzothiophene (DBT), to exert an inhibiting effect. The results suggest that IGTS8 may follow two different metabolic pathways in stationary-growth-phase cells or under growing conditions. The first pathway is characterized by oxidative steps, which convert DBT to DBT sulfoxide and to DBT sulfone. The sulfone is transformed to 2-(2′-hydroxyphenyl)benzene sulfinate and then to HBP and sulfite by a sulfinic acid hydrolase. In the second pathway the sulfone is further oxidized to 2-(2′-hydroxyphenyl)benzene sulfonate and then to HBP and sulfate by a sulfonic acid hydrolase. Experiments using benzene sulfonic acid suggest that the sulfonic acid hydrolase is an induced enzyme.
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  • 37
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The microbial ecology of different Spanish coal samples has been studied. Several bacteria have been isolated from enrichment cultures and characterised and their biodesulphurization abilities evaluated. Using morphological and physiological properties, different isolates have been related to species of the Xanthomonas, Pseudomonas, Chryseomonas and Moraxella genera. Some of the isolates, B(30)15 and T(30)10, gave important levels of organic desulphurization, close to 70%. Other isolates, B(30)7 and B(30)8, were able to remove inorganic sulphur with high efficiencies, over 67%. One of the isolates, B(30)10, metabolically related to Xanthomonas maltophila, was able to remove both organic and inorganic sulphur at neutral pH, with efficiencies of 69% and 68% respectively. The results obtained underline the potential use of some of these strains for industrial coal desulphurization processes.
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  • 38
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A new bacterial strain able to cleave CS bonds from organosulphur heterocyclic compounds through the 4-S pathway and tentatively classified as Arthrobacter sp. was recently isolated. In the present short article we describe the cloning and the characterization of the DNA encoding the enzymes responsible for desulphurization in this microorganism, referred to as Arthrobacter sp. DS7. The desulphurization operon was found to be located in a large plasmid that also bears the genes conferring cadmium and arsenic resistance. By shortening this plasmid, a new cloning vector was prepared and used to obtain a recombinant derivative strain that desulphurizes dibenzothiophene despite of the presence of inorganic sulphur in the growth medium.
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  • 39
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Traditional as well as biotechnological processing of coal leads to complex mixtures of products. Besides chemical and physical characterization, which provides the information for product application, there is a need for bioassays to monitor properties that are probably toxic, mutagenic or cancerogenic. Investigations carried out focused on the selection, adaptation and validation of bioassays for the sensitive estimation of toxic effects. Organisms like bacteria, Daphnia magna and Scenedesmus subspicatus, representing different complexities in the biosphere, were selected as test systems for ecotoxicological and mutagenicity studies. The results obtained indicate that bioassays are, in principle, suitable tools for characterization and evaluation of coal-derived substances and bioconversion products. Using coal products, coal-relevant model compounds and bioconversion products, data for risk assessment are presented.
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  • 40
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Addition of sodium acetate to chemically defined MP2 medium was found to increase and stabilize solvent production by Clostridium beijerinckii BA101, a solvent-hyperproducing mutant derived from C. beijerinckii NCIMB 8052. C. beijerinckii BA101 demonstrated a greater increase in solvent production than C. beijerinckii NCIMB 8052 when sodium acetate was added to MP2 medium. In 1-l batch fermentations, C. beijerinckii BA101 produced 32.6 g/l total solvents, with butanol at 20.9 g/l, when grown in MP2 medium containing 60 mM sodium acetate and 8% glucose. To our knowledge, these values represent the highest solvent and butanol concentrations produced by a solventogenic Clostridium strain when grown in batch culture.
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  • 41
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Amino acids have been produced with the aid of microorganisms for nearly 40 years now. The economic importance of these cellular building blocks is enormous. Demand for them is rising continuously and currently more than 106 tonnes/year are required. Continual efforts to increase production performance are directed towards the microorganisms themselves, as well as towards technical improvements of the respective processes. A special position within the amino-acid-producing microorganisms is traditionally occupied by Corynebacterium glutamicum. Molecular research in conjunction with NMR studies of flux has revealed fascinating new properties of this particular organism, including the existence of a new type of exporter and reverse fluxes within the anaplerosis. The knowledge gained will enable the further improvement of production strains and furthermore extend fundamental insights into metabolite flux management within bacteria in general.
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  • 42
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Industrial biotechnology has evolved as a significant manufacturing tool for products like fuel-grade ethanol, organic acids and bulk amino acids, but most items are still speciality products for food and pharmaceutical applications. Current development projects within the chemical industry, including lactic acid and 1,3-propanediol based polymers and plastics, indicate that new biotechnological processes and products may soon approach the market place, clearly targeted at the leading petrochemical bulk outlets. This is flanked by a strategic shift by the major chemical companies in to “life sciences”–pharmaceuticals, agrochemicals and the seed business as well as biotech fine chemicals. The recent tremendous achievements in molecular plant genetics and transgenic crop breeding will boost agro-biotechnology, agriculture and renewable raw materials as compelling projects for chemistry and biotechnology. New plant-based production routes may challenge established chemical and biochemical domains, but at the same time open new horizons to valuable feedstocks, intermediates and end-products.
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  • 43
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A general procedure for the high yield immobilization of enzymes with the help of specific anti-enzyme antibodies is described. Polyclonal antibodies were raised against Aspergillus niger glucose oxidase and horseradish peroxidase in rabbits and the gamma globulin (IgG) fraction from the immune sera isolated by ammonium sulphate fractionation followed by ion-exchange chromatography. Immobilization of glucose oxidase and horseradish peroxidase was achieved by initially binding the enzymes to a Sepharose matrix coupled with IgG isolated from anti-(glucose oxidase) and anti-(horseradish peroxidase) sera, respectively. This was followed by alternate incubation with the IgG and the enzyme to assemble layers of enzyme and antibody on the support. The immunoaffinity-layered preparations obtained thus were highly active and, after six binding cycles, the amount of enzyme immobilized could be raised about 25 times over that bound initially. It was also possible to assemble layers of glucose oxidase using unfractionated antiserum in place of the IgG. The bioaffinity-layered preparations of glucose oxidase and horseradish peroxidase exhibited good enzyme activities and improved resistance to heat-induced inactivation. The sensitivity of a flow injection analysis system for measuring glucose and hydrogen peroxide could be remarkably improved using immunoaffinity-layered glucose oxidase and horseradish peroxidase. For the detection of glucose, a Clark-type oxygen electrode, constructed as a small flow-through cell integrated with a cartridge bearing immunoaffinity-layered glucose oxidase was employed. The hydrogen peroxide concentration was analysed spectrophotometrically using a flow-through cell and the layered horseradish peroxidase packed into a cartridge. The immunoaffinity-layered enzymes could be conveniently solubilized at acid pH and fresh enzyme loaded onto the support. Immunoaffinity-layered glucose oxidase was successfully used for the on-line monitoring of the glucose concentration during the cultivation of Streptomyces cerevisiae.
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  • 44
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Limonene-1,2-epoxide hydrolase (LEH) from Rhodococcus erythropolis DCL14, an enzyme involved in the limonene degradation pathway of this microlorganism, has a narrow substrate specificity. Of the compounds tested, the natural substrate, limonene-1,2-epoxide, and several alicyclic and 2-methyl-1,2-epoxides (e.g. 1-methylcyclohexene oxide and indene oxide), were substrates for the enzyme. When LEH was incubated with a diastereomeric mixture of limonene-1,2-epoxide, the sequential hydrolysis of first the (1R,2S)- and then the (1S,2R)-isomer was observed. The hydrolysis of (4R)- and (4S)-limonene-1,2-epoxide resulted in, respectively, (1S,2S,4R)- and (1R,2R,4S)-limonene-1,2-diol as the sole product with a diastereomeric excess of over 98%. With all other substrates, LEH showed moderate to low enantioselectivities (E ratios between 34 and 3).
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  • 45
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The gene encoding phenylacetaldehyde reductase (PAR), a useful biocatalyst for producing chiral alcohols, was cloned from the genomic DNA of the styrene-assimilating Corynebacterium sp. strain ST-10. The gene contained an opening reading frame consisting of 1,158 nucleotides corresponding to 385 amino acid residues. The subunit molecular weight was calculated to be 40,299, which was in agreement with that determined by polyacrylamide gel electrophoresis. The enzyme was sufficiently expressed in recombinant Escherichia coli cells for practical use and purified to homogeneity by three-column chromatography steps. The predicted amino acid sequence displayed only 20–29% identity with zinc-containing, NAD+-dependent, long-chain alcohol dehydrogenases. Nevertheless, the probable NAD+- and zinc-binding sites are conserved although one of the three catalytic zinc-binding residues of the zinc-containing, long-chain alcohol dehydrogenases was substituted by Asp in PAR. The protein contains 7.6 mol zinc/mol tetramer. Therefore, the enzyme was considered as a new member of zinc-containing, long-chain alcohol dehydrogenases with a particular and broad substrate specificity.
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  • 46
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Laccase can be used for enzymatic detoxification of lignocellulosic hydrolysates. A Saccharomyces cerevisiae strain with enhanced resistance to phenolic inhibitors and thereby improved ability to ferment lignocellulosic hydrolysates would presumably be obtained by heterologous expression of laccase. Sequencing of the cDNA for the novel laccase gene lcc2 from the lignin-degrading basidiomycete Trametes versicolor showed that it encodes an isoenzyme of 499 amino-acid residues preceded by a 21-residue signal peptide. By comparison with Edman degradation data, it was concluded that lcc2 encodes an isoenzyme corresponding to laccase A. The gene product of lcc2 displays 71% identity with the previously characterized T. versicolor lcc1 gene product. An alignment of laccase sequences revealed that the T. versicolor isoenzymes in general are more closely related to corresponding isoenzymes from other white-rot fungi than to the other T. versicolor isoenzymes. The multiplicity of laccase is thus a conserved feature of T. versicolor and related species of white-rot fungi. When the T. versicolor lcc2 cDNA was expressed in S. cerevisiae, the production of active enzyme was strongly dependent on the temperature. After 3 days of incubation, a 16-fold higher laccase activity was found when a positive transformant was kept at 19 °C instead of 28 °C. Similar experiments with Pichia pastoris expressing the T. versicolor laccase gene lcc1 also showed that the expression level was favoured considerably by lower cultivation temperature, indicating that the observation made for the S. cerevisiae expression system is of general significance.
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  • 47
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We have successfully secreted the amino-terminal functional domain of mouse sonic hedgehog protein (SHH) into culture fluid using a yeast Pichiapastoris expression system. A cDNA fragment encoding the amino-terminal domain of mouse SHH was inserted downstream of the Saccharomyces cerevisiaeα-mating factor secretion signal. The DNA fragment was introduced into the host genome by the spheroplast transformation method. Transformants were selected based on their resistance to G418. His+ transformants which showed resistance to over 8 mg G418/ml were selected and analyzed for determination of the plasmid copy number. One His+ clone which has eight copies of the expression cassette per genome was cultured in minimal medium deficient for histidine, and further cultured in buffered medium supplemented with methanol which activates the AOX1 promoter. SDS-PAGE analysis indicated efficient expression and secretion of mouse SHH into culture fluid. The yield of secreted SHH was estimated to be 50 μg/ml. Purified protein was assayed for biological activity and found to activate the transcription of the Patched genes (Ptc-1 and Ptc-2) encoding receptors for SHH.
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  • 48
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract β-Poly(l-malate) (PMLA) production in Physarum polycephalum has been followed by using d-[1-13C]glucose and Ca13CO3. Nuclear magnetic resonance studies of PMLA showed that the 13C label from [1-13C]glucose was incorporated in the presence of CaCO3 into positions C-3 (-CH2-) and C-4 (-CO-) of the l-malate repeating unit of PMLA. The 13C label from Ca13CO3 was incorporated into position C-4 and indicated that not only the endogenous CO2 but also the exogenous CO2 from CaCO3 served significantly as a carbon source for PMLA production. In the absence of CaCO3, the 13C labeling pattern of PMLA from d-[1-13C]glucose was almost indistinguishable from that for the natural abundance 13C-NMR spectrum of the polymer. These results indicated that l-malate used for PMLA production is synthesized either via carboxylation of pyruvate and reduction of oxaloacetate in the presence of CaCO3 or via the oxidative tricarboxylic acid (TCA) cycle in the absence of CaCO3. Avidin strongly inhibited the formation of l-malate via carboxylation; the 13C labeling pattern of PMLA in the presence of CaCO3 was almost identical with that for the natural abundance spectrum when avidin was added, indicating that l-malate utilized for PMLA production was supplied under this condition by the oxidative TCA cycle.
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  • 49
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Rhizomucor pusillus 1116R3 has a defect in alg2 encoding a mannosyltransferase in the asparagine (N)-linked oligosaccharide biosynthetic pathway and produces proteins in less-glycosylated forms. For development of a genetic transformation system for this zygomycete, an uracil auxotroph (mutant 1116U17) as the host strain was derived by ultraviolet (UV) mutagenesis as 5-fluoroorotic acid-resistant colonies and the orotidine-5′-monophosphate (OMP) decarboxylase (pyr4) gene as a selection marker was cloned from the wild-type strain R. pusillus F27 by the polymerase chain reaction with primers designed on the basis of the pyr4 sequences from other fungi. The amino acid sequence of R. pusillus Pyr4 deduced from the nucleotide sequence showed high homology with the OMP decarboxylases from various fungi. The pyr4 gene on pUC19 (plasmid pRPPyr4) was introduced into protoplasts of R. pusillus 1116U17 by polyethylene glycol-assisted transformation. Transformation under optimized conditions yielded 5 Ura+ transformants with 1 μg pRPPyr4 DNA and 1 × 107 viable protoplasts. Southern blot analysis of the genomic DNA from the transformants showed that multiple copies of the pRPPyr4 sequence were integrated into the genome by homologous recombination at the pyr4 locus. For the purpose of production of a milk-clotting aspartic proteinase (MPP) in a less-glycosylated form, mpp from the wild-type strain was cloned in pRPPyr4 and introduced into protoplasts of R. pusillus 1116U17. Transformants obtained in this way contained multiple copies of mpp at the chromosomal mpp locus and produced MPP as a mixture of molecules having no sugar chains and Man0∼1GlcNAc2 at the two N-linked glycosylation sites in an amount about 12 times larger than the parent strain. The transformation system for R. pusillus 1116U17 would be useful for production of proteins with truncated N-linked oligosaccharide chains.
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  • 50
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract When 120 mg glucose/ml was used as a carbon source, in shake culture Aspergillus niger Yang no. 2 maximally produced only 15.4 mg citric acid/ml but accumulated 3.0 mg extracellular polysaccharide/ml. The polysaccharide secreted by mycelia of Yang no. 2 in shake culture was confirmed to be an amylose-like α-1,4-glucan by hydrolysis analysis with acid, amylase and glucoamylase. However, in static cultures, such as semi-solid and surface cultures free from physical stresses caused by shaking damage, Yang no. 2 produced more citric acid but did not accumulate the polysaccharide. With cultivation time in shake culture, the amount of extracellular polysaccharide and the viscosity of the culture broth increased. The increase of shaking speed caused a remarkable increase in the accumulation of extracellular polysaccharide, e.g. 11.2 mg extracellular polysaccharide/ml was accumulated in the medium at a shaking speed of 200 rpm. The addition of 2.0 mg carboxymethylcellulose (CMC)/ml as a viscous additive to the medium reduced drastically the amount of extracellular polysaccharide accumulated to 1.5 mg/ml, but increased the citric acid produced to 52.0 mg/ml. However, intracellular polysaccharide accumulation kept up a steady rate of 0.26 μg/mg dried mycelium through the entire period of cultivation. The addition of 3.0 mg polysaccharide/ml purified from the culture broth to the medium at the start of a culture resulted in a decrease of extracellular polysaccharide accumulation but an increase of citric acid accumulation. From electron-microscopic observation, cell surfaces of hyphae cultivated with CMC were smooth, while hyphae cultivated without CMC had fibrous and granular polysaccharide on the cell surface. These results suggested that Yang no. 2 secreted the polysaccharide on the cell surface as a viscous substance and/or a shock absorber to protect itself from physical stresses caused by shaking damage in shake culture.
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  • 51
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The role of gravity in the autolysis of Bacillus subtilis and Escherichia coli was studied by growing cells on Earth and in microgravity on Space Station Mir. Autolysis analysis was completed by examining the death phase or exponential decay of cells for approximately 4 months following the stationary phase. Consistent with published findings, the stationary-phase cell population was 170% and 90% higher in flight B. subtilis and E. coli cultures, respectively, than in ground cultures. Although both flight autolysis curves began at higher cell densities than control curves, the rate of autolysis in flight cultures was identical to that of their respective ground control rates.
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  • 52
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The effects of alginate on the physiological activities of plant cells were studied. Addition of alginate oligomer (AO) to the suspension culture of Catharanthus roseus L. or Wasabia japonica cells promoted the production of antibiotic enzymes such as 5′-phosphodiesterase or chitinase respectively. Ajmalicine (a secondary metabolite) production by C. roseus CP3 cells was also promoted when AO was added to the suspension culture. On the basis of these results, we assumed that alginate is an elicitor-like substance. We therefore compared the effect of AO on C. roseus L. and W. japonica cells with those of chitosan oligomer (CO) and oligo-galacturonic acid (OGA), which are well known as an exogenous elicitor and endogenous elicitor respectively. The effects of various concentrations of AO, OGA, and CO on the physiological activities, membrane permeability and protoplast formation of C. roseus L. or W. japonica cells were investigated. AO and OGA showed similar physiological effects, which were quite different from those of CO. Since alginate appeared to have similar effects to galacturonic acid, we concluded that alginate acts as an endogenous elicitor. Both alginate and galacturonic acid are uronic acids, and we considered their structural similarity. The effects of esterification of the carboxylic groups of alginate by propylene oxide were also studied. The greater the degree of esterification, the less the secretion of 5′-phosphodiesterase. Hence we assumed that carboxylic groups have an important role in the initiation of the elicitation reaction in plant cells, as shown in the case of galacturonic acid.
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  • 53
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Although isolated on 4-aminobenzoate, Burkholderia cepacia strain PB4 is also able to grow on 4-nitrobenzoate. Degradation of an equimolar mixture of the nitroaromatic compound 4-nitrobenzoate and its corresponding aminoaromatic derivative 4-aminobenzoate by this strain was investigated. Batch experiments showed that, irrespective of preculturing conditions, both compounds were degraded simultaneously. The mixture-degrading ability of B. cepacia strain PB4 was subsequently tested in continuous packed bed reactors (PBR) with the strain immobilized on Celite grade R-633 or R-635. Higher degradation rates were achieved with the larger particles of Celite R-635. Maximum simultaneous degradation rates per liter of packed bed of 0.925 mmol l−1 h−1 4-nitrobenzoate and 4-aminobenzoate were obtained for an applied loading rate of the same value (0.925 mmol l−1 h−1 of each compound). Even when the applied load was not removed in its entirety, neither of the two compounds was degraded preferentially but a percentage of both of them was mineralized. The present study shows the possibility for a pure strain to biodegrade not only a nitroaromatic compound (4-nitrobenzoate) but also its corresponding amino derivative (4-aminobenzoate) continuously and simultaneously.
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  • 54
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract On-line monitoring of NAD(P)H fluorescence and 2D fluorescence spectroscopy was performed with Enterobacter aerogenes, a bacterium sensitive to oxygen availability. The organism was grown in a reactor under low and high dissolved oxygen concentrations and circulated through a bypass attached to the reactor. Under low dissolved oxygen concentration in the reactor, NAD(P)H fluorescence in the reactor and the bypass showed a deviation, but not when the dissolved oxygen level in the reactor was high. The pattern of growth curves was identical under low and high oxygen levels. This indicates a difference in the metabolic activity of E. aerogenes in response to oxygen. The difference spectrum of the 2D fluorescence shows that growing E. aerogenes under high dissolved oxygen levels increases the NAD(P)H content of the cells.
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  • 55
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Highly substituted arenesulfonates are chemically stable compounds with a range of industrial applications, and they are widely regarded as being poorly degradable. We did enrichment cultures for bacteria able to utilise the sulfonate moiety of 14 compounds, and we obtained mixed cultures that were able to desulfonate each compound. The products formed were usually identified as the corresponding phenol, but because we could not obtain pure cultures, we followed up these findings with quantitative work in pure cultures of, e.g., Pseudomonas putida S-313, which generated the same phenols from the compounds studied. Many of these phenols are known to be biodegradable, or to be subject to binding to soil components. We thus presume that the capacity to degrade aromatic sulfonates extensively is widespread in the environment, even though the degradative capacity is spread over several organisms and conditions.
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  • 56
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effect of glucose on growth and anthracycline production by Streptomyces peucetius var. caesius was examined in a chemically defined medium. Glucose concentrations above 100 mM inhibited anthracycline synthesis in the original strain without causing significant change in growth and final pH values. This effect was observed when the carbohydrate was added initially or after 24 h fermentation, but not when added during the stationary growth phase. When the microorganism was pregrown in 100 mM glucose and then transferred to a resting cell system with 444 mM glucose, no significant differences in antibiotic production were observed compared to the control without glucose. The negative effect of glucose on antibiotic synthesis was not observed in a mutant (2-dogR–21) resistant to growth inhibition by 2-deoxyglucose. Glucose consumption by this mutant was approximately 30% of that utilized by the original strain. Compared to the original strain, the mutant 2-dogR–21 exhibited a reduction of 50% in glucose transport and an 85% decrease in glucose kinase activity. The experimental evidence obtained suggests that glucose represses anthracycline formation in a transitory manner and that this effect is related to glucose transport and phosphorylation.
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  • 57
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The esterification reaction between stearic acid and lactic acid using Rhizomucor miehei lipase and porcine pancreas lipase was optimized for maximum esterification using response surface methodology. The formation of the ester was found to depend on three parameters namely enzyme/substrate ratio, lactic acid (stearic acid) concentration and incubation period. The maximum esterification predicted by theoretical equations for both lipases matched well with the observed experimental values. In the case of R. miehei lipase, stearoyl lactic acid ester formation was found to increase with incubation period and lactic acid (stearic acid) concentrations with maximum esterification of 26.9% at an enzyme/substrate (E/S) ratio of 125 g mol−1. In the case of porcine pancreas lipase, esterification showed a steady increase with increase in incubation period and lactic acid (stearic acid) concentration independent of the E/S ratios employed. In the case of PPL, a maximum esterification of 18.9% was observed at an E/S ratio of 25 g mol−1 at a lactic acid (stearic acid) concentration of 0.09 M after an incubation period of 72 h.
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  • 58
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A mixed culture of algae was used to treat pulping mill effluent in terms of removing both colour and adsorbably organic halides (AOX). The removal of AOX from pulping effluent increased with increasing initial colour value of the effluent. However, for the total mill effluent (composed of both pulping and bleaching effluents), AOX removal was found to be independent of initial colour value, and was around 70%. Up to 80% removal of colour from pulping effluent was achieved within 30 days under continuous lighting conditions. It was found that algae reduced the colour of pulping effluent of relatively low initial colour more efficiently than that of high initial colour. Under simulated field lighting conditions, up to 60% colour removal from pulping effluent was observed after 60 days of exposure, whereas for the total mill effluent it was up to 64% after 45 days. Total organic carbon and lignin (UVA280) were also removed to a significant extent, suggesting that the mechanism of colour removal might not be transformation of the coloured lignin molecules to non-coloured ones. Analysis of alkaline extraction of the algal biomass and material balance findings indicated that the main colour removal mechanism was metabolism rather than adsorption. The experimental results were also analysed using multiple regression techniques and a mathematical model was developed to express the removal of colour from pulping effluents in terms of initial colour value, exposure time and lighting periods as well as interactions between these variables.
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  • 59
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    Electronic Resource
    Springer
    Applied microbiology and biotechnology 52 (1999), S. 612-612 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 60
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Spent Saccharomyces cerevisiae cells from a beer fermentation process were evaluated for lead cation sorption. The crude biomass was washed with water and acetone prior to any other treatment. Although the washed biomass showed substantial lead ion sorption it was susceptible to microbial spoilage. Different aldehydes were tested as chemical fixation agents; however, most of them caused drastic lowering of the metal uptake capacity. However, benzaldehyde was not only an excellent fixation agent, but the biomass treated with it also retained its original lead sorption capacity. A mechanism for the fixation process is suggested.
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  • 61
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Chloroaromatic compounds are xenobiotics that cause great concern. The degradation of a model molecule, 3,4-dichlorobenzoate (3,4-DCB), was studied using three aerobic (AE)-anaerobic (AN) biofilm reactor systems: a coupled aerobic-anaerobic recycle biofilm reactor (CAR) system, an in-series anaerobic-aerobic biofilm reactor (SAR) system; and an independent aerobic and anaerobic biofilm reactor (IAR) system. In all three systems the inlet substrate concentration was 2.0 g/l and the dilution rates ranged from 0.045 to 0.142 per hour. The results show that the degradation efficiency of the CAR system (expressed as dechlorination and xenobiotic disappearance efficiencies, and biomass yield), was higher at all dilution rates tested than in both SAR and IAR systems. Moreover, dechlorination and xenobiotic disappearance efficiencies for resting suspended aerobic and anaerobic cells or mixed aerobic-anaerobic growing cells under anaerobic conditions were higher than under aerobic conditions. These results suggest that a “cooperative metabolism” between aerobic and anaerobic bacteria (caused by an exchange of cells and metabolites between AE and AN reactors) in the CAR system overcame the metabolic and kinetic limitations of aerobic and anaerobic bacteria in the AE and AN reactors of IAR and SAR systems. Therefore, the degradation efficiency of persistent and recalcitrant chloroaromatic xenobiotic compounds could be enhanced by using a CAR system.
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  • 62
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The biological degradation of complex mixtures of recalcitrant substances is still a major challenge in environmental biotechnology and the remediation of coal-tar constitutes one such problem area. Biofilm bioreactors offer many advantages and may be successfully used for this purpose. Two stirred-tank reactors and one packed-bed reactor were tested in a continuous mode. Continuous cultivation allows microbial selection to take place whilst adhesive growth provides a high degradation capacity and process stability. The reactors were inoculated with mixed microbial populations to favour complete metabolism and to prevent metabolite accumulation and substrate inhibition effects. Phenol, o-cresol, quinoline, dibenzofuran, acenaphthene and phenanthrene were used as model contaminants and constituted the sole energy and carbon sources. The hydraulic retention time (HRT) was initially set to 2.5 days for a period of several months to allow the establishment of a stable biofilm and was then gradually decreased. All the compounds were found to be degraded by more than 90% at HRT of 3 h or more. Neither substrate inhibition nor metabolite accumulation effects were observed. The stirred-tank configuration was found to be the most efficient for use with high loads. No improvement in the degradation capacity could be achieved by increasing the biofilm surface in these reactors, illustrating that the limiting factor may be the mass transfer limitations rather than the availability of the biofilm surface. Finally, anaerobic treatment was successfully achieved, confirming the potential for remediation of contaminated sites under anaerobic conditions, providing that alternative electron acceptors are present.
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  • 63
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Many attempts have been made for the last six decades to design defined media for species of the lactococcus group. The general outcome of the studies suggests that this group is heterogeneous with respect to specific requirements for nutrients. Lactococcal species are limited in various metabolic pathways. Early attempts to trace the required nutrients were not always successful because of the poor quality of analysis and the presence of impurities in the medium components.
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  • 64
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Bacteriocins produced by lactic acid bacteria are a heterogeneous group of peptide inhibitors which include lantibiotics (class I, e.g. nisin), small heat-stable peptides (class II, e.g. pediocin AcH/PA1) and large heat-labile proteins (class III, e.g. helveticin J). Many bacteriocins belonging to the first two groups can be successfully used to inhibit undesirable microorganisms in foods, but only nisin is produced industrially and is licensed for use as a food preservative in a partially purified form. This review focuses on the production and purification of class I and class II bacteriocins from lactic acid bacteria. Bacteriocin production is growth associated but the yield of bacteriocin per unit biomass is affected by several factors, including the producing strain, media (carbohydrate and nitrogen sources, cations, etc.) and fermentation conditions (pH, temperature, agitation, aeration and dilution rate in continuous fermentations). Continuous fermentation processes with cell recycle or immobilized cells can result in a dramatic improvement in productivity over batch fermentations. Several simple recovery processes, based on adsorbing bacteriocin on resins or silica compounds, have been developed and can be used to build integrated production processes.
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  • 65