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  • Articles  (31,133)
  • 1975-1979  (15,884)
  • 1970-1974  (15,249)
  • Process Engineering, Biotechnology, Nutrition Technology  (31,133)
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  • Articles  (31,133)
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Year
  • 1
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Whole cells of Zygosaccharomyces lactis have been covalently linked to fine-grained hydroxyalkyl methacrylate gel Spheron P 1000 E which was prepared by treatment with epichlorhydrin and modified by an amine spacer. Experiments on the coupling of permeabilized and non-permeabilized cells to this gel support have shown that immobilized cell agregates may be obtained by the immobilization of thermally permeabilized cells. Cell clustering can be bypassed by immobilizing non-permeabilized cells. This immobilization procedure makes additional permeabilization possible.
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  • 2
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Soybean trypsin inhibitor immobilised to sub-micron ferrite particles functions as an affinity adsorbent for trypsin and the adsorbed enzyme may be recovered following elution in dilute acid. Trypsin can be adsorbed from casein solutions that is has digested. Equilibrium is reached in under 2 min with an effective dissociation constant as low as 10−7 M, allowing recoveries of more than 90% of added enzyme under realistic conditions. These results suggest that bioaffinity adsorbents could be used to recover an enzyme that has converted a macromolecular substrate. The operation of such a process is discussed, and some interactions are described that could be used with suitably high affinity adsorbents for other enzymes.
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Attempts were made to entrap enzymes or microbial cells with water-insoluble photo-crosslinkable resin prepolymers of different types in organic solvent systems in the presence or absence of water. Acetone-dried cells of Artbrobacter simplex immobilized in a maleic polybutadiene gel (PBM-2000) converted hydrocortisone to prednisolone in a phosphate buffer. 4-Androstene-3,17-dione was converted to androst-1,4-diene-3,17-dione in benzene-n-heptane solution by Nocardia rhodocrous which was immobilized by a hydrophobic prepolymer, ENTP-2000. The ENTP-2000 had been synthesized from poly(propylene glycol)-2000, hydroxyethylacrylate and isophorone diisocyanate. Even enzymes catalyzing aqueous phase reactions, such as catalase and invertase, were immobilized in a polybutadiene resin (PB-200k) to give active gel-entrapped preparations. The cells and enzymes immobilized in these hydrophobic resins exhibited moderate activities compared with those of the free cells and enzymes.
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  • 4
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The simultaneous measurement of protein and DNA content of yeast on a cell by cell basis is described. A problem associated with partially overlapping fluorescence emission bands of the two fluorochromes is discussed. The rapid flow cytometric assay will be useful to monitor cell growth in industrial fermentation processes.
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  • 5
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A polysaccharide-producing Gram-negative bacterium was isolated from a sample of hay. It grew best on nitrate-containing media with sucrose as carbon source; the colony form was highly unusual. No polysaccharide was formed on glucose. A spontaneous mutant producing the same polysaccharide on both sucrose- and glucose-containing media was isolated. The polysaccharide has been characterized as an acid heteropolymer containing D-galacturonic acid, D-glucose, D-galactose and D-mannose in the approximate molar ratio 1:1:3:1, together with about 2 mol of acetate. The polysaccharide in aqueous solution was highly viscous with pseudoplastic characteristics.
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  • 6
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A strain of the yeast Lipomyces kononenkoae which converted starch into SCP with a high yield, produced three extracellular amylases which were purified from the culture fluid by Ficoll concentration, dialysis, isopropanol precipitation and DE-cellulose chromatography: an α-amylase, a glucoamylase and a debranching transferase. The latter transferred α-1,6-glucosyl units from panose to glucose forming maltose and appeared to have some debranching activity on amylopectin. The α-amylase had the following properties: MW 38000 daltons; no effect of added calcium ions on activity; optimum temperature and pH for activity around 40°C and pH 5.5; ΔH
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  • 7
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Biomass harvested from batch and single-stage continuous cultures of the fungus Geotrichum candidum, growing on the spent wash from an Irish malt whiskey distillery, was analysed for macromolecular components. The ‘true’ protein content was on average more than 47% (w/w), while ‘crude’ protein levels of as much as 61% were found. The protein was not deficient in any amino acid when compared to the FAO standard. The effects of varying growth temperature and dilution rate on the composition of the organism are discussed, and also the problem of its accumulation of copper from the medium.
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  • 8
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A strain of the imperfect fungus Geotrichum candidum was selected for its ability to utilize the low-pH, high biochemical oxygen demand (BOD) waste generated by an Irish malt whiskey distillery. Growth of the organism on this complex medium, in both batch and continuous culture, showed a sequential assimilation of the major components with the most complete carbon assimilation (63.7%) being achieved in batch culture. Optimum temperature for the continuous culture of the organism was found to be 22°C; at this temperature and at a dilution rate of 0.125 h−1 a productivity of 2.24 g l−1 h−1 was obtained. Variations in organism morphology, produced by varying growth rate and nutritional or environmental factors, as well as the potential of the process for the production of single cell protein from carbohydrate-rich waste are discussed.
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  • 9
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Photophosphorylation of ADP catalyzed by chromatophores represents a possible method for regenerating ATP from ADP for use in large-scale enzymatic synthesis of complicated molecules. We found that the extent of conversion of ADP to ATP in the presence of ascorbate and magnesium chloride was influenced by the presence of bubbling gas in contact with the reaction mixture, and by the presence of fumarate: with no fumarate or gas contact, low conversions (usually about 50%) were obtained; however, under the same conditions, but in the presence of fumarate or bubbling gas, 100% conversions were obtained. We discuss mechanistic implications of our findings.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The concentration dependence of the foaming of aqueous bovine serum albumin (BSA) solutions with and without salt additives and that of the turbidity temperature, TT, of p-isononylphenol-10-glycolether in presence of KCl, MgSO4, or K4 [Fe(CN)6] were determined. The differences between the turbidity temperatures of the solutions with and without salt additives were used to calculate the apparent concentration BSA in the salt solutions and to estimate their foaming. The measured and calculated foaminesses agree well.
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  • 11
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The flocculation of Chlorella vulgaris by Lactobacillus casei was studied to determine whether the latter could act as a suitable flocculant for the removal of Chlorella from algal ponds. The flocculating activity of the Lactobacilli was caused by the bacterial cells themselves, and not by diffusible products of bacterial metabolism. Diffusible products of algal metabolism inhibited flocculation. For algae resuspended in water, the best flocculation occurred at pH values less than 3.5 where the charges on the bacterial and algal cells were opposite. For flocculation at least one bacterium was required for every algal cell; in terms of cell concentrations,10 mg/l of bacteria were required to flocculate an algal suspension of 1,000 mg/l. The mechanism of flocculation implied by the results is that positively charged cells of L. casei adsorb to the surface of negatively charged cells of C. vulgaris neutralizing the charge and thus destabilizing the algal suspension. Because of the low pH required and because diffusible products of algal metabolism inhibit the flocculation, it is unlikely that L. casei could be usefully employed as a flocculant of Chlorella from algal ponds.
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  • 12
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary To develop an efficient method for continuous production of L-malic acid from fumaric acid using immobilized microbial cells, screening of microorganisms having high fumarase activity was carried out and cultural conditions of selected microorganisms were investigated. As a result of screening microorganisms belonging to the genera Brevibacterium, Proteus, Pseudomonas, and Sarcina were found to produce fumarase in high levels. Among these microorganisms Brevibacterium ammoniagenes, B. flavum, Proteus vulgaris, and Pseudomonas fluorescens were further selected for their high fumarase levels in the cultivation on several media. These 4 microorganisms were entrapped into a k-carrageenan gel lattice, and the resultant immobilized B. flavum showed the highest fumarase activity and operational stability. Cultural conditions for the fumarase formation and the operational stability of fumarase activity of immobilized B. flavum are detailed. Productivity for L-malic acid using immobilized B. flavum with k-carrageenan was 2.3 fold of that using immobilized B. ammoniagenes with polyacrylamide.
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  • 13
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Penicillium cyaneum, isolated from an, oil-field, was grown in batch culture on media containing glucose or kerosene alone, or both glucose and kerosene. Arachidonic acid was produced in highest yield (7.5%; 200 μg per g dry weight of organisms) in media containing glucose and kerosene or kerosene alone. No effect on the arachidonic acid yield was observed when either yeast extract or sodium nitrate was used as the nitrogen source. Higher yields of intracellular fatty acids and arachidonic acid were obtained at 27°C than at 32°C.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary D(−)-3-hydroxybutanoic acid was produced by a double mutant of Alcaligenes eutrophus, unable to synthesize poly-3-hydroxybutanoic acid and to utilize 3-hydroxybutanoate as a substrate. About 3.4 g of 3-hydroxybutanoate/l were produced under optimum conditions at pH 7.0 to 7.3, at a temperature of 30°C after exhaustion of ammonia and at restricted aeration rates allowing 10–12% of the maximum respiratory rate of the cells to occur. D(−)-3-hydroxybutanoic acid was identified by means of gas and ion exchange chromatography, IR-spectrometry and specific rotation.
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  • 15
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Growth of Aspergillus niger and Cladosporium herbarum occurred in shake cultures with polyurethane as the sole nutrient source. Simultaneously, the isocyanate almost completely disappeared from the polyurethane as determined with an IR-spectroscope. Otherwise, no structural changes were found in the polyurethane, though both fungi penetrated into the resilient foam tested.
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  • 16
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The respiration rate-dependent formation of metabolites and of poly-3-hydroxybutanoate was studied with wild type and mutant strains of Alcaligenes eutrophus. Several metabolites were excreted during restricted respiration, each metabolite at a distinct relative respiration rate. The relative respiration rate was defined as the ratio (in percent) of the respiration rate during the production phase to that at the end of the exponential growth phase. The following metabolites were excreted: Ethanol, 1-propanol and 2-methyl-1-propanol at 2.4, D,L-2,3-butanediol at 4.4, meso-2,3-butanediol at 5.1, acetoin at 4.4 to 5.5, 2-methylpropanoate, 2-methylbutanoate and 3-methylbutanoate at 5 to 6, succinate at 5.5, formate at 6.7, molecular hydrogen at 5 to 7, acetate at 7.2, butanoate at 7.4, 3-hydroxybutanoate at 10 to 11, cis-aconitate at 20.6, 2-oxo-3-methylbutanoate at 26.5, and 2-oxoglutarate at about 50%. The maximum formation of poly-3-hydroxybutanoate occurred at 40 to 50%. When the respiration rate was not restricted, the substrate was completely oxidized. The excretion of metabolites is a very useful indicator for the oxygen nutrition of the cells. The respiration rate correlated positively with the availability of oxygen and negatively with that of gluconate. Upon addition of gluconate (1.5%), the respiration rate immediately decreased.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Isolation and enrichment cultures were made for anaerobic cellulose utilizing micro-organisms from non-ruminant sources. Stable mixed cultures were developed which degraded pure cellulose (wet-milled filter paper) in a defined mineral salts medium. Components of the mixed cultures lost viability in monoculture when grown on cellulose. Growth on cellulose was stimulated at low oxygen concentrations, when increased cellulase activity and increased volatile fatty acid production occurred. Low concentrations (0.1–3 mM) of cellobiose, and to a lesser extent, glucose stimulated solubilization of cellulose by the cultures, but higher concentrations had an inhibitory effect. Growth on cellulose was accompanied by production of acetic, propionic and butyric acids. The production and profile of the acids was stable and characteristic of the culture. When an ‘open’ nonaseptic fermentation was employed, the fatty acid profile was variable and also included valeric acid.
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  • 18
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A survey was made of maize and barley in Germany for the occurrence of toxigenic strains of Fusarium and of the mycotoxins produced in culture by these strains. The following 6 species of Fusarium were found: F. avenaceum, F. culmorum, F. equiseti, F.oxysporum, F. poae, and F. tricinctum. The species most commonly isolated from bird-damaged maize ears was F. avenaceum while F. culmorum was consistently isolated from maize stem rot. The predominant species in barley grain was F. poae while F. avenaceum, F. culmorum, and F. tricinctum were also isolated frequently. Cultures on autoclaved maize of all the Fusarium strains were assayed for toxicity by feeding to 1-day-old chickens for 14 days. Some strains of F. avenaceum, F. culmorum, F. equiseti, and F. oxysporum proved to be acutely toxic to chickens and caused mortality as well as marked reductions in weight gain and feed consumption. All the strains of F. poae and F. tricinctum had a low degree of toxicity. Culture material of all the strains were analyzed for the presence of 11 known Fusarium mycotoxins. The following 4 mycotoxins were detected in the strains examined: moniliformin in 9 out of 9 F. avenaceum strains (2 to 760 ppm) and in the single strain of F. oxysporum (1150 ppm); zearalenone in 4 out of 5 F. culmorum strains (320 to 1400 ppm); deoxynivalenol in 3 out of 5 F. culmorum strains.(1 to 15 ppm); and acetyldeoxynivalenol (1 to 2 ppm) in 3 out of 5 F. culmorum strains. This is the first report of moniliformin production by F. avenaceum and F. oxysporum and also the first report of the occurrence of moniliformin-producing Fusarium strains in Europe.
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  • 19
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The uptake of various 14C labelled compounds like (1-14C) glucose, (1-14C) acetate, (2-14C) uracil, (1-14C) leucine and (14C−CH3) methionine was studied in Aspergillus parasiticus. A comparative study of asparagine deficient, zinc deficient and SLS cultures revealed different growth patterns. High lipid levels under zinc and asparagine deficiency were observed. During the stationary phase the synthesis of proteins and DNA declined. The uptake of 14C labelled glucose, methionine and acetate was maximum in asparagine deficient cultures during the transitional and stationary phase of growth. Maximum uptake of labelled methionine and glucose occured during the exponential growth phase (45 h). The uptake of labelled leucine was highest under asparagine deficiency during the exponential and transitional phases but reached a minimum during stationary phase. The uptake of labelled uracil remained high throughout in the asparagine deficient cultures. The mechanism of inhibition of aflatoxin biosynthesis in the absence of zinc and asparagine seems to be different.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The surface tension σ and foaminess Σ of (a) unlimited, (b) substrate limited, and (c) oxygen transfer limited growth media of Hansenula polymorpha were measured using methanol, ethanol or glucose as a substrate. The time dependence of σ can be described by the Avrami-Überreiter relationship: log (2.3 log V)=n log t+log b, where V = (σO − σeq/(σt − σeq, and σO, σt and σeq are σ at tM=0, tM=t and tM→∞ (equilibrium value). The constants n and b are functions of the fermentation time tF as long as the growth is unlimited but they are constant in the state of limited growth. With glucose substrate, the foaminess Σ can be presented as a definite function of the time, tDG, which is necessary to attain σeq. With alcohol as a substrate no definite Σ (tDG) function was found.
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  • 21
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Electrical conductivity microprobes have been used to estimate the transverse variation of bubble size, local gas holdup and local specific gas/liquid interfacial area in bench scale bubble column bioreactors containing fermentation model media. Inserted O2-electrodes and plane parallel windows alter the structure of the two phase flow. Even slight tilting of the column strongly influences the transverse profiles of the bubble size and local gas holdup. The larger bubbles are collected at the wall, where they can be redispersed. These observations open up new possibilities for the construction of bubble column bioreactors.
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  • 22
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Whole cells of Pseudomonas fluorescens which utilized mainly glucose were immobilized in collagen membrane. The microbial electrode consisted of a bacteria-collagen membrane and an oxygen electrode was developed for the determination of glucose. When the electrode was inserted in a sample solution containing glucose, the current of the electrode decreased markedly with time until a steady state was reached. The response time of the electrode was 10 min by the steady state method. A linear relationship was observed between the steady state current and the concentration of glucose below 20 mg l −1. The minimum concentration for determination was 2 mg of glucose per liter. The reproducibility of the current was examined using the same sample solution. The current was reproducible within ±6% of the relative error when a sample solution containing 10 mg {ie343-1} of glucose was employed. The standard deviation was 0.6 mg {ie343-2} in 20 experiments. The reusability of the glucose sensor was examined using the same sample solution (10 mg {ie343-3}). No decrease in current output was observed over a two week period and 150 assays. Glucose in molasses was determined with an average relative error of 10% by the microbial electrode sensor.
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  • 23
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Microbial cells and cellular organelles were immobilized by mixing aqueous suspensions of the biocatalysts with water-miscible urethane prepolymers. Thus immobilized preparations of acetone-dried cells of Arthrobacter simplex and thawed cells of Nocardia rhodocrous showed appreciable {ie351-1} activities in the transformation of hydrocortisone into prednisolone and 4-androstene-3,17-dione to androst-1,4-diene-3,17-dione, respectively. The activities of catalase and alcohol oxidase were observed in the immobilized peroxisomes (microbodies) of a methanol-grown yeast Kloeckera sp. No. 2201. Yeast mitochondria entrapped with the prepolymer showed adenylate kinase activity. These results indicate the usefulness of the urethane prepolymers as convenient materials for entrapment of not only enzymes, but also organelles and microbial cells.
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  • 24
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Baker's yeast (Saccharomyces cerevisiae) was cultivated under different intensities of aeration on glucose and on ethanol. Seventeen enzymes of the Embden-Meyerhof pathway and the TCA cycle or related reactions were then assayed by starch gel electrophoresis. There were both qualitative and quantitative differences in many enzymes, most notably in glyceraldehyde-3-phosphate dehydrogenase, alcohol dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase, and fumarase. Enzyme electrophoresis seems to offer a promising method for rapidly obtaining information about many yeast enzymes from a large number of samples.
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  • 25
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Glucose, 2-deoxy glucose and inorganic phosphate inhibited tylosin production and fatty acid oxidation in Streptomyces T 59–235. Glucose-6-phosphate was accumulated in high-phosphate cultures. The possible function of glucose phosphate as a common mediator of both glucose and phosphate effects is discussed.
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  • 26
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The potential of hydroxyalkyl methacrylate gel as a support for yeast cell immobilization by covalent attachment was investigated with respect to the length of spacer used and the manner of its activation. Saccharomyces paradoxus cells were immobilized successfully onto glutaraldehyde activated glycyl-, β-alanyl-and ε-aminocaproyl-derivatives of the above mentioned gel modified with hexamethylenediamine. Results suggest that covalent attachment via spacer is strongly influenced by cell surface characteristics.
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  • 27
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Factor analysis was applied to fermentation of whey by Kluyveromyces fragilis IMAT 1872 allowing a screening of the experimental variables (temperature, pH, ammonium sulphate, potassium phosphate, yeast extract and lactose concentration and fractional filling of the flasks). The lactose level and the ratio of the solution and flask volumes have a marked effect on the biomass yield, as they control the oxygenation level of the culture media. Nutritional supplementation and environmental conditions have only a marginal effect on yield in this fermentation process. The best fit obtained by regression analysis between the biomass yield and the first principal component of factor analysis (oxygenation factor) showed a linear relationship: 64% of the data fall within a 25% deviation band.
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  • 28
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A composite design technique was used to optimize the fermentation of whey by Kluyveromyces fragilis IMAT 1872. The experimental variables (temperature T, salts NP, yeast-extract YE and lactose level L), but not pH, were found to be significant at a level of 5%. The optimal operating conditions were determined (T=36.4°C, pH=5.1, NP=0.47% w/v, YE=0.114% w/v, and L=24.75 g/l). Temperature and lactose level exhibited a great influence on the biomass yield about the stationary point. Canonical analysis showed that these variables are not mutually independent. The optimal conditions will be used as starting point for a factorial design on a jar fermenter.
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  • 29
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Streptomyces rimosus culture filtrates after oxytetracycline production were shown to contain a number of hydrolytic enzymes in concentrations high enough to indicate their exploatation. Crude enzyme preparations were obtained using precipitation, salting out and spray-drying methods. The presence of acid, neutral, and alkaline protease and their elastolytic, esterolytic and collagenolytic activities were discerned. Substrate specificity, pH and temperature optimum, pH stability and molecular weight were studied. These proteases belonged to the group of serine and metalloenzymes. Carboxyl and thiol proteases were not present.
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  • 30
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Candida lipolytica is shown to produce an extracellular polymer with emulsifying properties when grown on n-tetradecane or a mixture of linear hydrocarbons. A device for biosurfactant isolation is presented. The polymers recovered from the fermentation broth were found to be complex molecules with a protein, a lipid and a carbohydrate moiety. Their surface active properties suggest a possible role in hydrocarbon uptake by cells. Effectively, the addition of crude polymer resulted in an enhancement of respiration rate which was dependent on n-alkane concentration with glucose grown cells. Likewise in batch culture, maximum growth rate, cell productivity and yield were increased by the presence of the biosurfactant.
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  • 31
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Production and release of cellulolytic enzymes by Trichoderma reesei QM 9414 were studied under induced and non-induced conditions. For that purpose, a method was developmed to produce cellulases by Trichoderma reesei QM 9414 using the soluble inducer, cellobiose, as the only carbon source. The production was based on continuous feeding of cellobiose to a batch culture. For optimum production, the cellobiose supply had to be adjusted according to the consumption so that cellobiose was not accumulated in the culture. With a proper feeding program the repression and/or inactivation by cellobiose could be avoided and the cellulase production by Trichoderma reesei QM 9414 was at least equally as high as with cellulose as the carbon source. During the cultivation, specific activities against filter paper, carboxymethyl cellulose (CMC) and p-nitrophenyl glucoside were analyzed from the culture medium as well as from the cytosol and the cell debris fractions. There was a base level of cell debris bound hydrolytic activity against filter paper and p-nitrophenyl glucoside even in T. reesei grown non-induced on glycerol. T. reesei grown on cellobiose was induced to produce large amounts of extracellular filter paper and CMC hydrolyzing enzymes, which were actively released into the medium even in the early stages of cultivation. β-Glucosidase was mainly detected in the cell debris and was not released unless the cells were autolyzing.
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  • 32
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A mixed bacterial culture which was obtained in a previous enrichment grew on parathion, an organophosphate insecticide, as a sole carbon and energy source. A cell-free enzyme preparation from this culture detoxified by hydrolysis eight commercially used organophosphate insecticides. Fermentation procedures for the production of this parathion hydrolase activity were examined to determine if this enzyme activity could be produced economically. The mixed culture was grown using sterile or non-sterile procedures in 4 or 11 ℓ continuous and batch culture fermentations. A pure Pseudomonas sp isolated from the mixed culture expressed parathion hydrolase activity when grown under axenic fermentation conditions on industrially used media such as meat extract, soya bean meal, and corn extract. The optimal conditions for production of parathion hydrolase activity were determined for both pure and mixed cultures. The yield of parathion hydrolase activity/ℓ of fermentation broth per hour was improved 22 fold by growing the pure culture on an industrial meat extract medium instead of the mixed culture on parathion.
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  • 33
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Phenol removal by pure cultures of Nocardia corallina was studied in a batch reacting system by estimating both the active biomass and the phenol concentration in the liquid during the experiments. A simple kinetic model was tested and the relative constants determined at 37°C.
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  • 34
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A stainless steel ‘T’ joint was used to simulate stagnant volume in a pipe-line. Residence time distribution in the lines was measured using a radiotracer (Cr51) which emitted γ radiation. The radiation was measured externally to the pipe line. From the experimental data the dead volume of the system was calculated. The effect of the depth of T and flow velocity on dead volume was evaluated. Labelled bacteria were used in some experiments instead of chromium. No significant difference in behavior between ionic chromium and bacteria labeled with chromium was found.
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  • 35
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The quantitative changes in constituents of rice straw during different stages of growth of the fungus Pleurotus flabellatus were investigated. Cellulose, hemicellulose(s), lignin, total carbon and total nitrogen showed a continuous decrease from inoculation until the end of fruit body harvesting, whereas free sugars, total ash and C/N ratio increased. As calculated on constant ash basis, 14 and 13.9% of cellulose, 6.6 and 7% of hemicellulose(s) and 4 and 1.5% of lignin were decomposed during the mycelial growth and fructification respectively. Total N decreased by 0.16 and 0.23% during the mycelial growth and fructification respectively. The progressive breakdown of cellulose and hemicellulose(s) was correlated to an apparent increase in the activities of celullase and hemicellulase(s). The trend in development of cellulases and β-glucosidase activities in the substrate during different stages of its growth was demonstrated.
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  • 36
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The paper described a simplified method for the separation, identification and determination of zearalenone by liquid chromatography in cereals. The cereal medium is dried, homogenised and extracted with ether. From the ether extract zearalenone is transferred into ethyl acetate, whereafter the sample is analysed using an external standard. The detection limit of the method is 500 μg/kg. Recoveries of zearalenone varied from 94.5% to 96.2%. The conditions of the liquid chromatography are described.
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  • 37
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Four isolates of Pseudomonas from soil and sewage utilized 3-chlorobenzoate (3-CBA) adaptively as sole source of carbon and energy. Two of these were studied in detail. Their doubling times in batch culture were about twice as long on chlorobenzoate as on benzoate or glucose. Both isolates showed oxygen uptake on catechol, without lag, when grown on either benzoate or 3-CBA. One strain, designated Pseudomonas H1, could oxidize a key intermediate, 4-chlorocatechol, only when grown on 3-CBA. Pseudomonas H2 could oxidize the chlorocatechol not only when grown on 3-CBA but also when grown on benzoate. Benzoate-adapted P. H1 therefore accumulated chlorocatechols when incubated with a mixture of 3-CBA and benzoate, whereas P. H2 under the same conditions did not. The accumulated chlorocatechols inhibited further oxygen uptake, and in alkaline media they polymerized to a black, melanin-like pigment. Intense black pigment, similar to that formed by P. I, was formed if raw sewage was incubated with a mixture of 3-CBA and benzoate. The pigment was not formed if the sewage was first adapted by incubation with 3-CBA.
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  • 38
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary From a petro chemical waste-water treatment plant showing sludge bulking, two filamentous microorganisms of the Leucothrix type were isolated. Morphological and some physiological characteristics of the isolates L1 and L2 were compared with the characteristics of two cool water strains of Leucothrix mucor. The main divergences of the isolates were the requirement for biotin and thiamine (L1) or for biotin alone (L2) and the non marine character, since they can grow at a salinity of 5 ppt, without NaCl. It is suggested that the isolates may be new species of the genus Leucothrix, that can cause sludge bulking.
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  • 39
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The accumulation of cadmium from aqueous systems by various green microalgae was investigated with focus, on Chlorella regularis as it is known to concentrate large amounts of heavy metals. The amount of cadmium absorbed by Chlorella cells was rapid during the first 30 min following addition of cadmium and then continued to be absorbed more slowly. The uptake of cadmium by Chlorella was not markedly affected by temperature or metabolic inhibitors. Most of the cadmium absorbed by Chlorella cells was easily released by EDTA. The amount of cadmium absorbed differed markedly with the pH value of the solution and was inhibited by the presence of other divalent cations. Heat-killed Chlorella cells took up cadmium to a greater degree than living ones. From these results, it was considered that the uptake of cadmium into Chlorella cells was not directly mediated by metabolic processes, rather it appeared completely dependent upon physico-chemical adsorption on the cell surface. The ability to accumulate cadmium was species specific and found to be (in decreasing order); Chlamydomonas reinhardtii〉Chlorella regularis〉 Scenedesmus bijuga〉Scenedesmus obliquus〉Chlamydomonas angulosa〉 Scenedesmus chlorelloides.
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  • 40
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The applicability of hydrogenase determinations to the evaluation of hydrogen transfer reactions occurring within methanogenic environments was investigated. Enzymatic hydrogen production was determined in digester sludge, river sediments, and rumen liquid using reduced methyl viologen, formate, and pyruvate as hydrogen donors. Hydrogenase determinations turned out not to be inhibited by toxic compounds present in sediments of the polluted river Saar. Comparative kinetic studies of the conversion of acetate and of hydrogen to methane support the assumption that carbon dioxide reduction by hydrogen accounts for the major part of methane formed in river sediments. In rumen liquid and in river sediments similar enzyme patterns were observed which were different from that found in digester sludge. The rates of methanogenesis correlated well with hydrogenase activities in all ecosystems studied: Correlation coefficients ranged from 0.84 to 0.95. Rumen liquid and river sediments exhibited higher hydrogenase activities than digester sludge when compared at identical rates of methane production. According to these results, the hydrogenase determination is applicable to the evaluation of the hydrogen transfer, occurring within the microbial biomass of anaerobic ecosystems.
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  • 41
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The trichothecene, vomitoxin, was found in two Austrian corn samples at levels of 1.3 and 7.9 ppm and in one Canadian corn sample at a level of 7.9 ppm; all three corn samples were rejected when fed to swine. Feed made from the latter corn sample contained 1.4 ppm vomitoxin. Kernels from these corn samples were examined for Fusarium graminearum. The mold was found only in the two Austrian corn samples, and four of the isolates produced vomitoxin at levels ranging from 3.7 to 16.7 ppm.
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  • 42
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new immobilization of microbial cells based on the growth of cells in gel is presented. The cells grew very well in carrageenan gel when fed nutrients required for growth. The growing cells immobilized in gel formed a dense layer of cells near the gel surface. Because the cells were near the gel surface, they efficiently catalyzed single enzyme reactions. In addition, the immobilized growing cell system was applied to the complicated multienzyme reactions since large numbers of cells in the gel could constantly be maintained for long periods.
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  • 43
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary An ultrafiltration membrane enzymatic reactor is used in connection with different reacting systems. The experimental conditions are such that the enzyme, which operates at fairly high concentration levels because of the concentration polarization phenomena taking place in the reactor, is still in soluble form. The analysis of the system unsteady-state response enables the identification of the mechanism of enzyme deactivation and the extraction of the kinetic parameters of both the deactivation and the main reaction. The stabilizing effect observed in connection with enzyme entrapment within an inert gel deposited onto the U.F. membrane active surface is also discussed.
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  • 44
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A production of macerating enzymes which liquefy and hydrolyze the mandarin orange peel was studied in a solid state cultivation of Aspergillus niger on wheat bran substrate. Solid state cultivation in a 2 ℓ drum fermenter capable of interchangeable operation under dynamic or static conditions were carried out maintaining the moisture content of the substrate at 32, 39, 46, 56, 67, and 74%. Biomass grown on the solid substrate was estimated on the basis of a constant value of glucosamine content of A. niger, 50 mg glucosamine/g cell. A linear relationship between oxygen uptake rate and growth rate observed in all the experiments gave an oxygen growth yield, YX/O, of 28.5 g cell/mol O2. The rate of macerating enzyme formation was also in proportion to the growth rate irrespective of the difference of the moisture content of the substrate. The enzyme accumulation on the solid substrate, the growth rate and oxygen uptake rate were maximum when the moisture content of the substrate was maintained at ca. 56% ascending from 32 to 56 and descending from 56 to 74.
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  • 45
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The generic classification of yeasts is based mainly on morphological characteristics whereas the definition of a species depends predominantly on physiological properties such as the utilization of carbon and nitrogen sources. Classification procedures are routinely done on agar slants, and in negative tests single colonies are often noticed. These colonies are spontaneous mutations and can be idetified as such after transfer onto adequate media and appropriate genetic tests. It is sometimes possible after selection steps to obtain a completely different ‘species’. This means that in many cases the classification depends only on single gene differences, where the differences in DNA base homology is almost certainly less than 1%. Since it is rather difficult to justify a new species on the basis of a single biochemical gene mutation, it is necessary in practice to perform at regular intervals an extended series of physiological tests in order to avoid confusion in nomenclature.
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  • 46
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary 1. A continuous two stage cultivation method for two strains of Klebsiella pneumoniae and Escherichia coli yielding high cell mass and relatively high glycogen contents is described. The stage 1 cells (carbon-limited) were fed with the nitrogen source ammonia (which also neutralized simultaneously) soly via the pH-stat. In stage 2, the cells grew nitrogen-limited, a small excess of the carbon source was maintained by continuous addition of a glucose solution. 2. Through the action of lysozyme, the glycogen could be quantitatively solubilized from the alkali-insoluble cell material obtained through alkaline hydrolysis of the cells in dimethylsulfoxide-3M aqueous potassium hydroxide. The possibility that the glycogen is in part covalently linked to the peptidoglycan and localized in the periplasm is discussed. 3. Analytical data for the glycogens isolated from the two bacterial strains is given.
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  • 47
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A microbial electrode consisting of immobilized living whole cells of yeasts, porous membrane and an oxygen electrode was prepared for continuous estimation of biochemical oxygen demand (BOD). Immobilized Trichosporon cutaneum was employed for the microbial electrode sensor for BOD. When a sample solution containing the equivalent amount of glucose and glutamic acid was injected into the sensor system, the current of the electrode decreased markedly with time until steady state was reached. The response time was within 18 min. A linear relationship was observed between the current decrease and the concentration below 41 mg l − of glucose and 41 mg l − glutamic acid (5-day BOD 60 mg l −). The current decrease was reproducible within ± 6% of the relative error when a sample solution containing 27 mg l − of glucose and 27 mg l − of glutamic acid (5-day BOD 40 mg l −) was employed. The microbial electrode sensor was applied to untreated waste waters from a fermentation factory. Good comparative results were obtained between BOD estimated by the microbial electrode and that determined by the conventional 5-day method (regression coefficient was 1.2). Furthermore, the effect of various compounds on BOD estimation was also examined. The current output of the microbial electrode sensor was almost constant for 17 d and 400 tests.
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  • 48
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The heat resistance of Klebsiella pneumoniae, an organism of widespread occurrence in nature has been determined in media containing various amounts of sucrose at temperatures between 47° and 59°C. In the presence of sucrose and at all temperatures the inactivation curves show a fast initial drop (logarithmic phase) in the number of survivors followed by a less rapid one (tail phase). The influence of the sucrose concentration can be described with ln k s = ln k O − αT [sucrose] for media with more than 0.52 mol/l sucrose for the logarithmic as well as for the tail phase of inactivation. The heat-injured cells were recovered on various media to investigate the influence of the presence of small metabolites and nutrients on the shape of the inactivation curves and on the death rate. For cells heated in media without sucrose, the recovery on a rich medium was much better than on a poor one; for cells heated in media with more than 0.26 mol/l sucrose, no difference was observed between the various recovery media. The activation energies as determined on the various media are always nearly the same, which strongly suggests that the critical sites in the heat inactivation were not enzymes playing a key role in the synthesis of small molecules such as amino acids or nucleotides.
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  • 49
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    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The photographic and electrical conductivity methods to measure the structure of two phase flow, especially bubble size, bubble frequency, local gas hold-up and, for the latter, the bubble velocity are described.
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  • 50
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Population changes in the levels of mesophilic and thermophilic bacteria, fungi and actinomycetes during composting of spruce-bark were studied. The composting rate was determined as a function of the amount of CO2 developed per unit of time. Composting was performed under controlled conditions of the various environmental parameters in a bench scale composter. Temperature was controlled at 45°C during the process. Inoculation with bark compost and determination of the content of carbo-hydrates during spruce-bark composting were studied.
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  • 51
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary (1) In a parallel study, samples of food and dairy products, bacterial cultures and spore suspensions were examined by two operators using both the spiral plate and surface drop techniques for counting bacteria. (2) Statistical analyses of the results showed no differences between the methods at the 5% level of probability; regression and correlation coefficients were highly significant. A variation between paired counts of less than 0.5 log10 cycles was given by 95% of the samples. (3) The replicate variances of both methods were 〈0.006, indicating good agreement betweeen duplicate plates. (4) An electronic laser counter used in this study was found to give comparable results (r=0.966) to the grid-method of colony counting in a substantially shorter time. (5) Analysis of operation times and material requirements for each method showed that significant savings in cost, time, space and support labour could be achieved with the spiral plate method over conventional techniques.
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  • 52
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Enzymatic production of L-tryptophan has been studied in a system containing Escherichia coli cells (induced for tryptophanase) entrapped in a polyacrylamide gel, indole and excess pyruvate and ammonia. The influence of pH, substrate concentration and temperature on L-tryptophan production, in batch and flow reactor conditions, was investigated. In flow reactor conditions, inhibition of the reaction by indole resulted in a multi steady-state pattern characteristic of substrate inhibited reactions. Any increase in flow rate at indole concentrations higher than 17 mM resulted in a dramatic decrease in the conversion rate of indole to tryptophan. A device for the practical production of L-tryptophan, which involves feeding a limiting concentration of indole to a reactor, adsorption of the synthetized tryptophan and recycling of excess pyruvate and ammonium ions was tested.
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  • 53
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Whole cells of Achromobacter butyri OUT 8004 having polyphosphate glucokinase activity were immobilized in polyacrylamide gel. The immobilized cells were activated by organic solvents, especially acetone. The immobilization resulted in increased stability of polyphosphate glucokinase. Continuous high yield production of G-6-P from glucose and metaphosphate was performed with an immobilized cell column, which had a half-life of approximately 20 days.
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  • 54
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Reducing oligosaccharides were covalently linked to the spacer arm of aminohexyl Sepharose by reductive amination. The reaction was carried out in the presence of sodium borohydride in aqueous medium under mild experimental conditions. An affinity column containing lactose-coupled Sepharose was used for the purification of α,α-trehalase from Artemia salina embryos.
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  • 55
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The change in the α-glucoside permease activity of baker's yeast, Saccharomyces cerevisiae, has been followed in the presence of maltose and/or glucose in the medium. Three separate effects of glucose on the permease were distinguished: an immediate effect that apparently involves a conformational transformation of the permease, an inactivation of the permease before the initiation of growth, and a repression and derepression of the synthesis of permease. Conceivable mechanisms for regulation of the glucose effects are briefly discussed.
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  • 56
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Polysaccharide formation by Rhodococcus erythropolis was studied using lower mono-, di-and trihydric alcohols, sugars and n-alkanes as carbon sources. Cultural conditions of the organism were examined with regard to polysaccharide production. It was demonstrated that a glycerol substrate, an 30°C incubation temperature and a pH of 7.5 were optimal cultural conditions for polysaccharide formation. Addition of penicillin G in the decelerating growth phase increased the polysaccharide concentration in the culture filtrate to 3.1 g/l. One of the main extracellular heteropolysaccharides formed by Rhodococcus erythropolis consisted of glucose and mannose in the molar ratio 1∶1, a small portion of protein and a trace of glucosamine. The molecular weight was to be 1·14×106.
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  • 57
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Escherichia coli cells, carrying plasmid pRD1 with (a) drug resistance markers from Pseudomonas (kmr, carbr, tcr) and (b) the nif-gene group from Klebsiella, were incubated together with Bacillus subtilis cells (strr), whose cell wall had been disintegrated with lysozyme. Upon plating the cell mixtures onto appropriately supplemented selective medium, multiple drug resistant Bacillus subtilis cells were obtained. Their nature was verified by suitable biochemical tests and checking for the presence of additional genetic markers. The majority of the isolates was unstable. Some however retained multiple drug resistance for longer periods of time, and several produced nitrogenase activity. The data are interpreted as evidence not only for the transfer of the respective genes but also for their expression in the gram-positive recipient cells.
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  • 58
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The effect of hydrostatic pressure on the activity of Thiobacillus ferrooxidans grown on chalcopyrite concentrate has been investigated. It was found that bacterial activity, measured by conventional respirometry, was little affected by subjecting these microorganisms to a pressure of 100 lbs/in2 (690 kPa). The total cooper concentration was as high as 18 g/l in 28 days of leaching at atmospheric pressure.
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  • 59
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The municipal solid waste of Rome, processed by the Dano plant, has been studied in the stabilization phase. During the different composting stages the following were determined: pile temperature, pH, moisture content, microbiological counts on compost extract and on other media, and mycological investigations. Twenty four days in January were necessary for the compost stabilization.
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  • 60
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The effect of lithium on growth and aflatoxin production in chemically defined medium was studied on three aflatoxigenic strains of Asperigillus flavus group. The three strains used differed in their aflatoxin producing capacities. The possible mechanism of lithium induced stimulation of aflatoxin biosynthesis is discussed.
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  • 61
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Whole cells of Arthrobacter simplex were immobilized in a living state in calcium alginate gel. The bacteria showed steroid-Δ1-dehydrogenase activity and the production of prednisolone from cortisol was investigated. The Δ1-dehydrogenase activity of the immobilized cells could be increased about ten-fold by incubation in nutrient media (e.g., containing 0.5% peptone abd 0.2% glucose). The reason for this activation was examined and it was found that the immobilized cells were capable of multiplying when supplied with nutrients. Furthermore, provided that an inducer, cortisol, was present, the steroid-Δ1-dehydrogenase activity increased in proportion to the increase in the number of cells and it was thus concluded that microbial growth was the cause of activation. Experiments on repeated, batch-wise pseudocrystallofermentation with immobilized A. simplex cells also showed that immobilized cells could be advantageously used for pseudocrystallofermentation of steroids.
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  • 62
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A population of mixed rumen bacteria was maintained in a chemostat at four different dilution rates, with glocose as the growth limiting carbon and energy substrate. Increasing the dilution rate shifted the proportions of end products: methane decreased and propionate increased. Fermentation and hydrogen balances were calculated from the fermentation end products. Values were similar to earlier ones from batch incubations of rumen contents. This suggests that theoretical overall reaction schemes for carbohydrate fermentation in the rumen, proposed earlier, are also valid in continuous culture. A positive correlation between dilution rate and microbial growth efficiency (gNinc./kg OMf was observed, confirming earlier work. Apparently conflicting results of chemostat work and recent in vivo experiments are discussed.
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  • 63
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A flask, designed for direct gassing of batch cultures of bacteria, was evaluated for its use in studying oxygen absorption rates (OAR) and suitability for physiological studies under various controlled atmospheres. Such flasks, aerated directly without shaking, yielded an OAR (up to 1.2 mmol O2/l/min) that was comparable to or higher than those obtained in conventional flasks aerated by shaking. Direct aeration in combination with shaking resulted in OAR values that were elevated and most favorable for growth of oxygen demanding bacteria (≈5 mmol O2/l/min). In comparison with controls, the direct method of aeration in combination with shaking proved most efficient and least dependent on the surface to volume ratio of the aerated solution. In experiments with the facultative anaerobe Streptococcus faecalis 10Cl, grown in controlled aerobic, anaerobic, and mixed gas (CO2-free air, air-plus-CO2, N2-plus-CO2) environments, a specific anaerobic requirement for CO2 could be established. The wide range of gaseous environments possible renders the newly tested flask useful for comparative biochemical studies, especially when the gaseous condition of culture is a factor of critical importance.
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  • 64
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A relatively simple procedure was developed to quantitate normal and methylated tRNA bases by isocratic HPLC. tRNA was extracted with phenol from lyophilyzed cells, purified and precipitated with isopropanol. After perchloric acid hydrolysis, the samples were subjected to HPLC analysis. The mole % composition of normal and methylated bases was determined in yeasts grown on unusual carbon sources including hydrocarbons and light alcohols. Normal and methylated base composition of total tRNA depends on the microorganism and on the carbon source used.
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  • 65
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary By applying photographic, electrical conductivity, and electrooptical methods, the transverse variation of bubble size and velocity, the local gas holdup, and the local specific gas/liquid interfacial area were estimated in a bench scale bubble-column bioreactor containing distilled water. The liquid velocity profile, the transverse turbulence intensity variations, and the turbulence energy dissipation scale were also measured by a hot film turbulence probe and constant temperature anemometer technique.
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  • 66
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Pseudomonas multivorans strain An 1 used aniline but not chloroanilines as the sole source of carbon and energy for growth. The aniline-adapted cells, however, were able to oxygenate chloroanilines. Relative oxygenation rates for aniline, 2-chloroaniline, 3-chloroaniline, 4-chloroaniline, and 3,4-dichloroaniline were 100, 46, 66, 20, and 3%, respectively. The first intermediates in the metabolism of chloroanilines were chlorocatechols. 3-Chlorocatechol accumulated during growth of the organism in the presence of 2-chloroaniline, whereas 4-chlorocatechol was an intermediate metabolite of 3-chloroaniline and 4-chloroaniline. Chloroanilines were able to induce synthesis of the aniline oxygenating enzyme system of Pseudomonas multivorans strain An 1. In continuous culture experiments, induction of this enzyme system appeared to depend on cell density, concentration, toxicity, and pK-values of aniline or chloroanilines. Studies with 14C-labelled 3-chloroaniline and 4-chloroaniline showed that the turnover of chloroanilines did not cease with the formation of chlorocatechols, because radioactivity was detected in the CO2 released and in bacterial cell components. The results suggest that the turnover of chloroanilines is due to metabolism rather than to cometabolism.
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  • 67
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Pseudomonas multivorans strain An 1 was isolated from forest soil after enrichment in a medium containing 0.1% aniline as the sole source of carbon and energy. Increasing aniline concentrations increasingly inhibited bacterial growth. At pH 7, aniline concentrations greater than 16mM were toxic enough to completely arrest growth. The optimal pH for growth on aniline was 6.5. On binary mixtures of aniline and additional carbon sources, diauxic growth was observed. The addition carbon sources caused various degrees of repression of the aniline catabolizing enzyme system. The fastest induction of this system occurred at pH 4, suggesting that protonization of the aniline molecule is crucial.
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  • 68
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Extracts of 9-day-old mycelia of Aspergillus parasiticus NRRL 2999 were assayed for peroxidase activity and for their ability to degrade aflatoxin. A positive relationship existed between rates of aflatoxin degradation and amount of peroxidase activity in these extracts. The supernatant fluid of homogenates from mycelia grown under similar conditions varied in amount of peroxidase present (170 to 2215 U/g). The fraction obtained, by precipitation with (NH4)2SO4 at 45% of saturation, from six different homogenates prepared from three mycelial mats contained peroxidase and degraded aflatoxin. Rates of aflatoxin degradation by and amounts of peroxidase activity in each sample obtained from mycelial homogenates with (NH4)2SO4 at 60% of saturation varied; however, when increased amounts of peroxidase activity were present, more aflatoxin was degraded and vice versa. Relatively little peroxidase activity was present in the fraction obtained with (NH4)2SO4 at 30% of saturation and little or no aflatoxin was degraded by this precipitate. Trends for degradation of aflatoxin when more or less peroxidase activity was present in mycelial preparations suggest that the enzyme may be involved in degradation of aflatoxin by the Aspergillus.
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  • 69
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The effects of light illumination and dissolved oxygen concentration (DO) on the growth characteristics of Rhodopseudomonas sphaeroides S and intracellular accumulations of vitamin B12 and photopigments were studied in continuous cultures of aerobic-dark (S-1, DO〉5 mg l−1), aerobic-light (S-2, DO〉5 mg l−1, 4.5 klux), microaerobic-light (S-3, DO≈0,4.5 klux) and anaerobic-light (S-4, 4.5 klux) conditions using propionate media. Growth yields from propionic acid determined in S-3 and 4 were 1.5 to twofold greater than in S-1 and 2. Carbon dioxide evolution observed in S-3 and 4 was 0.05 to 0.1 times that in S-1 and 2. Overall carboxylase activity was maximal in S-4. Intracellular accumulations of bacteriochlorophyll and carotenoid were maximal in S-4, followed by S-3 and almost nil in S-1 and 2. The high growth yields observed in S-3 and 4 could be accounted for the high level of activity of carbon dioxide fixation and by the additional or effective utilization of light energy. Intracellular accumulation of vitamin B12 in S-2, 3 and 4 was 1.5 to 1.8 times that in S-1. The maximum content of the vitamin was 74 μg-B12 g-cell−1. The maximum productivity of vitamin B12, μg-B12 l−1 h−1, was 6.6 in S-3 since specific growth rate, growth yield and the vitamin content of the cells were maximal in S-3.
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  • 70
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Foam control is an important part of every fermentation technology. Chemical anti-foam agents (AFA) are surface active substances, which decrease the surface elasticity of liquids and prevent metastable foam formation. Most AFA must be mixed or dissolved in a suitable carrier substance if their antifoaming properties are to be fully utilized. The carrier seems to act as a reservoir from which the AFA is liberated. The toxicity of different AFA upon Aspergillus niger was tested in Petri dishes. Their effect on the decrease of the respiration ability of the test organism A. niger was tested in a Warburg apparatus. Various AFA were tested as pure substances, as emulsions in seed oil and as mixtures of different AFA in cylindrical vessels with sinter glass discs under similar conditions as in the fermentor. Using mentioned methods the most suitable AFA were tested in citric acid fermentation on beet molasses.
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  • 71
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology