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• Biochemistry and Biotechnology  (167)
• 2010-2014
• 1975-1979  (167)
• 1970-1974
• 1977  (167)
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• 2010-2014
• 1975-1979  (167)
• 1970-1974
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• 1
Electronic Resource
New York, NY [u.a.] : Wiley-Blackwell
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 2
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 43-53
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The reliability of the process of Ramanathan and Gaudy (Biotechnol Bioeng., 13, 125 (1971)) for the completely mixed activated-sludge process holding the recycle cell concentration, XR, as a system constant with respect to step changes in hydraulic retention time was investigated. The experiments were run at initial dilution rates of ⅛, ⅙, ¼, and ½ hr-1 treating a soft drink bottling wastewater. The influent substrate concentration was maintained at 1000 mg/liter chemical oxygen demand and the hydraulic recycle ratio at 0.3. The recycle sludge concentration was maintained at about 7000 mg/liter.It was found that the system could accommodate hydraulic shock loads up to 200% positive changes and down to 50%negative changes without disruption of the effluent quality. Shorter retention time of the range studied, from 2 to 8 hr, has the advantage of shorter response time with respect to the response of the concentration of biological solids in the reactor.
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• 3
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 69-86
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The economics of yeast production depend heavily upon the cellular yield coefficient on the carbon source and the volumetric productivity of the process. The application of an on-line computer to maximize these two terms during the fermentation requires a continuous method of measuring cell density and growth rate. U fortunately, a direct sensor for biomass concentration suitable for use in industrial fermentations is not available. Material balancing, with the aid of on-line computer monitoring, offers an indirect method of measurement. Laboratory results from baker's yeast production in a 14-liter fermentor (with a PDP-11/10 computer for on-line analyses) show this indirect measurement technique to be a viable alternative. From the oxygen uptake and carbon dioxide production data, gas flow rate, and ammonia addition rate, the cell density during the fermentation has been estimated and found to compare well with actual fermentation data.
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• 4
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 143-152
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A rapid chemical procedure based on the solubility of a holocellulose sample in a system of dimethyl sulfoxide with paraformaldehyde has been developed to provide a laboratory method for predicting dry matter digestibility of cellulose containing samples. The amount of dry matter solubilized by the chemical procedure was closely correlated with anaerobic, in vitro, rumen fluid digestion and with digestibility as measured by aerobic Cellulomonas, sp. bacteria. The quantity of solvent and dissolving time had little effect on solubility over a wide range. The method is rapid, well suited for various cellulosic materials, and may be carried out with simple equipment and facilities.
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• 5
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 125-142
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Amyloglucosidase was covalently bound to collagen sheets by a previously described method. The time of acidic methylation (first step of the collagen activation process) was important to obtain a good enzymatic surfacic activity. Homogeneity of the coupling procedure on the surface of collagen films was shown. Some properties of free enzyme were not affected after grafting: optimum pH and temperature, activation energy, and Km for maltose. Heat stability of the bound enzyme was slightly better; Km for soluble starch increased fivefold. In contrast, the maximal velocity in the presence of soluble starch remained four times that of maltose hydrolysis.Amyloglucosidase collagen membranes were used in a helicoidal reactor to produce glucose from maltose or soluble starch solutions. Tracer studies have shown that the helicoidal reactor behaved as a CSTR. The influence of maltose concentration and flow rate on conversion was studied and confirmed the absence of diffusional limitations for maltose. Recycling of concentrated solutions of maltose and soluble starch indicated strong diffusional restrictions for soluble starch. The catalytic support kept all its activity for 18 days continuous operation at 40°C and 80% after 17 months storage at 4°C.
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• 6
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 157-158
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 7
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New York, NY [u.a.] : Wiley-Blackwell
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 8
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 159-184
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Glucose isomerase in the form of heat-treated whole-cell enzyme prepared from Streptomyces phaeochromogenus follows the reversible single-substrate reaction kinetics in isomerization of glucose to fructose. Based on the Kinetic constants determined and the mathematical model of the reactor system developed, the preformance of a plug-flow-type continuous-enzyme reactor system was studied experimentally and also simulated with the aid of a computer for the ultimate objective of optimization of the glucose isomerase reactor system.The enzyme decay function for both the enzyme storage and during the use in the continuous reactor, was found to follow the first-order decay kinetics. When the enzyme decay function is taken into consideration, the ideal homogeneous enzyme reactor kinetics provided a satisfactory working model without further complicatin of the mathematical model, and the results of computer simulation were found to be in good agreement with the experimental results. Under a given set of constraints the performance of the continuous glucose isomerase reactor system can be predicted by using the computer simulation method described in this paper.The important parameters studied for the optimization of reactor operation were enzyme loading, mean space time of the reactor, substrate feed concentration, enzyme decay constants, and the fractional conversion, in addition to the kinetic constants. All these parameters have significant effect on the productivity.Some unique properties of the glucose isomerization reaction and its effects on the performance of the continuous glucose isomerase reactor system have been studied and discussed. The reaction kinetics of glucose isomerase and the effects of both the enzyme loading and the changes in reaction rate within a continuous reactor on the productivity are all found to be of particular importance to this enzyme reactor system.
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• 9
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 235-246
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Continuous, steady-state grape-juice fermentation, carried out in experimental slant-tube fermentors, was characterized by complete fermentation, even at fast pumping rates, because efficient cell retention, as well as rapid yeast growth, quickly built cell density up to the limit permitted by the juice supply rate. Essentially complete fermentation was easily achieved with a juice residence time of 3.1 hr, compared to about 120 hr in normal batch fermentation. Successful continuous fermentation required constancy of gas and liquid flow through the tubes, placing some restrictions on choice of tube configurations. The validity of design equations, developed previously from a settling model, was tested, and some practical aspects of their application to fermentor design and operation were demonstrated.
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• 10
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 527-538
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Chaetomium cellulolyticum, a newly isolated cellulolytic fungus, showed 50-100% faster growth rates and over 80% more final biomass-protein formation than Trichoderma viride, a well-known high cellulase-producing cellulolytic organism, when cultivated on Solka-floc (a purified, predominantly amorphorous form of cellulose) or partially delignified sawdust (consisting of a mixture of hardwoods) as the sole-carbon source in the fermentation media. However, in both cases, T. viride produced much higher quantities of free cellulases at faster rates and also degraded more substrate than C. cellulolyticum. It is concluded that the synthesis mechanisms and/or the nature of the cellulase complexes of the two types of organisms are quite different such that C. cellulolyticum is more optimal for single-cell protein (SCP) production, while T. viride is more optimal for the production of extracellular cellulases.It was also found that the amino acid composition of C. cellulolyticum is generally better than that of T. viride and compares favorably with those of the FAO reference protein, alfalfa, and soya meal. In addition, preliminary feeding trials on rats have shown no adverse effects of the SCP produced by C. cellulolyticum fermentations.
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• 11
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 561-564
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 12
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 591-593
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 13
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 575-581
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 14
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 595-598
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 15
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 611-618
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 16
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 631-648
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Whole cells of Micrococcus luteus (formerly Sarcina lutea ATCC 9341) have been covalently linked to a carboxymethylcellulose support system, with the retention of histidine ammonia-lyase activity. The dependence of the rate of urocanic acid formation on pH, temperature, and added surfactant concentration was similar for the free and the immobilized cells.The immobilization procedure used is based on the carbodiimide activation of carboxymethylcellulose and has been optimized for the histidine ammonia-lyase activity of the immobilized cells on a given weight of cellulose.In a column reactor at 23°C and superficial velocity of 0.044 cm/min, 5 g of cellulose with bound cells gave a 35% conversion of an L-histidine solution (0.25M, pH 9.0) to urocanic acid for 16 days of continuous operation.The scope of this carbodiimide assisted immobilization procedure has been investigated for a series of microorganisms and a variety of carboxylate functionalized supports.
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• 17
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 683-700
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The milk-clotting enzyme pepsin was immobilized onto beads of alumina, titania, glass, stainless steel, iron oxide, and Teflon for treating skim milk in a fluidized-bed reactor. Two covalent attachment procedures using silanized supports and glutaraldehyde and two adsorption procedures were evaluated. The three best catalysts were titania and glass, using the covalent attachment procedure, and alumina, using the adsorption procedure at pH 1.2. The pepsin adsorbed on alumina catalyst has commercial potential compared to the previously used glass catalyst. Attempts to increase the stability of pepsin adsorbed on alumina by cross-linking with glutaraldehyde were unsuccessful owing to the low pH necessary for optimum pepsin adsorption. Desorption of pepsin from alumina during reactor operation was determined. Regeneration of spent catalysts was only partially successful.
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• 18
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 741-748
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 19
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 621-629
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The gas-liquid oxygen transfer rate is a key step in the production of antibiotics in submerged fermentation. If the gas-liquid oxygen mass transfer rate is not equal to the required liquid-solid oxygen mass transfer rate at a particular cell concentration, then productivity of the particular fermentation operation will not be the maximum possible value.One way to increase the productivity of a given fermentation tank installation is to increase the cell concentration and to increase the oxygen transfer by changing the mixer and air supply to match the new requirements. In order to evaluate the cost of making this change to the larger mixing equipment, a typical cost example is given which can easily be modified for other combinations of production cost and mixer cost. As an example, it is seen that a considerable savings can result from a given installation by primarily changing the oxygen transfer ability of the equipment to utilize a given fermentor more efficiently. Production cost savings of 8 to 25% are shown in the example cited.
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• 20
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 701-714
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The uptake mechanism of liquid hydrocarbons of low solubility in water was investigated, using microorganisms with different affinities for liquid hydrocarbon. Microorganisms which could utilize hydrocarbon were much more adherent to hydrocarbon than those which could not. The adhesive force between Candida intermedia IFO 0761 and hydrocarbon was higher than that of Candida tropicalis ATCC 20336, though both could utilize hydrocarbon. The total hydrocarbon uptake from the drop and accommodation forms of hydrocarbons was much higher than that from dissolved hydrocarbon. The uptake rate of drop-form hydrocarbon was nearly equal to that of accommodation-form hydrocarbon for C. intermedia, but was lower for C. tropicalis which shows lower adhesion to hydrocarbon.
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• 21
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1101-1114
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The kinetics of the reversible fumarase reaction of immobilized Brevibacterium ammoniagenes cells and the decay behavior of enzyme activity were investigated in a plug flow system. The time course of the reaction in the immobilized cell column was well explained by the time-conversion equation including the apparent kinetic constants of the immobilized cell enzyme. The decay rate of fumarase activity was faster in the upper sections of the column (inlet side of the substrate solution) compared with the lower sections when 1M sodium fumarate (pH 7.0) was continuously passed through the column at 37°C. It was shown that the decay rate of the fumarase activity in the immobilized cell column depends on the flow rate of the substrate solution. The effect of flow rate on the decay rate of enzyme activity was considered to be related to the rate of contamination of enzyme with poisonous substances derived from the substrate solution or to the rate of leakage of enzyme stabilizers and/or enzyme itself from the immobilized cells.
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• 22
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Biotechnology and Bioengineering 19 (1977), S. 1115-1123
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Trypsin was coupled on an agarose gel which was modified with a spiropyran compound. The trypsin-spiropyran (agarose) gel showed reverse photochromism. The activity of the trypsin-spiropyran gel in the dark was 12% of that of native trypsin, and it was higher than that under visible light. The apparent Michaelis constant of the trypsin-spiropyran gel in the dark was larger than that under visible light. On the other hand, the maximum velocity in the dark was higher than that under visible light. The optimum pH of the trypsin-spiropyran gel in the dark was the same as that under visible light. Immobilized trypsin was stable in the pH range from 3 to 9. The trypsin-spiropyran gel was more stable against heat than the native trypsin.
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• 23
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1155-1169
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Glucose-limited chemostat cultures of Candida utilis were cultivated at various pH levels (3.0-7.5), temperatures (15-37.5°C), dilution rates (0.06-0.42 hr-1), and with one of two nitrogen sources (NH4+ or NO3-). Enterobacter aerogenes was also cultivated in the chemostat under nitrogen and phosphorus limitations. The amino acid profile of total cell protein is expressed as the content of each amino acid relative to the sum of all amino acids recovered after acid hydrolysis. Cell residues obtained after hot trichloroacetic acid extraction display small variations in amino acid profile. Some of these variations correlate with the growth rate at satisfactory levels of statistical significance. In C. utilis, the correlations cover increased levels of lysine, arginine, and leucine and decreased levels of serine and glutamic acid with increased “reduced dilution rate” (D/Dc). In E. aerogenes, increased levels of lysine and arginine and a decreased level of glutamic acid correlate with increased dilution rate. The directions of most of these correlations and the extents of those pertaining to lysine and arginine are consistent with the change predicted to occur simultaneously in the relative level of the ribosomal protein group.
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• 24
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1405-1405
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 25
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New York, NY [u.a.] : Wiley-Blackwell
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 26
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1449-1462
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The efficiency of conversion of the carbon-energy source to product is of primary importance in many fermentation processes. In order to assess the efficiency of a process, one must know how close the actual conversion yield is to the theoretical maximum. Theoretical conversion yields are useful, therefore, as guides in improving a process. This knowledge is particularly important today because the cost of raw materials is rapidly rising. In this study, the biochemical pathway of penicillin synthesis was used to estimate the theoretical yield of penicillin from glucose, ammonia, and sulfate. These values are compared with experimental data from the literature. An analysis of the role of glucose in the synthesis of cell mass and penicillin and in the maintenance of cells makes it possible to assess the efficiency of carbon-source utilization and to direct further advances in penicillin fermentations.
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• 27
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1475-1491
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A pilot scale rotating biological contactor (RBC) was set up near a coal mine at Hollywood, Penn. to evaluate ferrous iron, Fe(II), oxidation. Acid drainage from this mine entered the treatment unit which consisted of four sets of plastic disks affixed to a rotating central shaft. As the disks rotated half immersed in the flowing mine water, iron-oxidizing bacteria, presumed to be Thiobacillus ferrooxidans, colonized the disk surfaces with an average population of 70,000 cells/cm2 and mediated the transformation of Fe(II) to the less soluble ferric state, Fe(III). Kinetics of microbial Fe(II) oxidation were established during an eleven month period of continuous pilot operation and were found to follow a concentration dependent first order relationship. Operating at an optimum disk rotation rate and hydraulic loadings of 2.7 and 5.4 gal/day-ft2 (0.11 and 0.22 m3/day-m2) resulted in the oxidation of an average 240 mg/liter influent Fe(II) to produce effluent Fe(II) of 2 and mg/liter, respectively. The RBC appears potentially useful as a first step in the total treatment of acid mine drainage.
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• 28
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New York, NY [u.a.] : Wiley-Blackwell
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 29
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1563-1621
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 30
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1667-1677
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The stereospecific hydrolysis of D,L-phenylalanine methylester with immobilized α-chymotrypsin was carried out as a model reaction for the racemate resolution of aromatic amino acids in a five staged fluidized-bed reactor (FBR). Owing to ester hydrolysis, a pH shift occurred along the reactor. Because of the pH-dependent enzyme activity a particular longitudinal pH profile had to be enforced by a proper entrance pH in order to gain an optimum conversion. In the FBR with optimum pH profile, higher conversions were achieved than in a continuous stirred tank reactor (CSTR) at the pH optimum and at the same contact time. By the application of a proton balance and the results of kinetic measurements a model was developed for the prediction of the optimum longitudinal pH profile with regard to the maximum conversion.
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• 31
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Biotechnology and Bioengineering 19 (1977), S. 1703-1714
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Papain and lipase were immobilized on derivatized Sepharose 4-B. The activated agarose had a binding capacity of 1.2 μmol amino groups/ml packed agarose or 17 mg proteins/g dry agarose. The immobilized enzyme preparations were tested for the effects of pH of assay, temperature of assay, and substrate concentrations. The effect of 6M urea on the activity of papain was also determined. Soluble forms of the enzymes were used for comparison. Immobilization of the enzymes resulted in slightly different pH and temperature optima for activities. For immobilized papain Km (app) was similar to the one observed with soluble papain. Immobilization of lipase, however, caused a decrease in Km values. The immobilized enzyme preparations were stable when stored at 4°C and pH 7.5 for periods up to eight months. The soluble enzymes lost their activity within 96 hr under similar storage conditions. Immobilized papain did not lose any activity after treatment with 6M urea for 270 min, whereas soluble papain lost 81% of its activity after the urea treatment, indicating that the immobilization of papain imparted structural and conformational stability to this enzyme.
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• 32
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Biotechnology and Bioengineering 19 (1977), S. 1885-1889
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 33
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Biotechnology and Bioengineering 19 (1977), S. 9-25
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: In hydrocarbon fermentation, the efficiency of hydrocarbon uptake by cells ins one of the keys to the economical production of single-cell protein. This work is concerned with characterization of cultures with two liquid phases for understanding the hydrocarbon uptake process by cells. Batch cultivation of Candida lipolytica was carried out in shaking flasks and in a tower fermentor with motionless mixers. Micorscopic observation and cell and hydrocarbon concentration distribution in batch cultivation showed that some cells are attached to the large oil drops ad others are free from them. Interfacial tension between oil and water and Sauter mean drop size decreased as cultivation proceeded. On the basis of the experimental results, the process of hydrocarbon uptake by cells is discussed.
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• 34
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Biotechnology and Bioengineering 19 (1977), S. 55-67
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Despite the importance of biomass as a parameter in fermentation processes, there are no commercially available sensors suitable for its measurement. An indirect approach for the assessment of biomass concentration can be based on material balances and on the direct monitoring of fermentation parameters for which there are established sensors (e.g., gaseous oxygen and carbon dioxide). As a consequence, this method requires no assumption of cellular yield coefficients or rate constants. This approach is also readily adaptable to general use since it requires only some knowledge of the compositions of the substrate, cells, and noncellular products.
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• 35
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 101-124
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Chymotrypsin has been immobilized to several nonporous magnetic materials. Nickel particles were considered to be most suitable as immobilized enzyme supports. Chymotrypsin immobilized to nonporous magnetic supports was not fouled significantly by6 either whole milk or clarified yeast homogenate. AE-cellulose-chymotrypsin was rapidly fouled by both these materials and chymotrypsin immobilized to acrylic-based ion exchangers was slowly fouled. Immobilized enzyme activity was found to be inverted proportional to particle diameter for nonporous rock magnetite particles. Immobilization by adsorption and then glutaraldehyde crosslinking was used to produce controlled amounts of chymotrypsin on the particles. Esterolytic activity increased with enzyme loading but caseinolytic activity did not increase. Chymotrypsin is inhibited by metal ions from the magnetic supports. It is partially protected by use of a preliminary protein coating and may be reactivated by incubation with EDTA or BSA.
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• 36
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 153-155
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 37
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 185-198
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The kinetic behavior of a system of multiple enzyme in solution has been studied in a variable volume batch reactor at pH 5, controlled dissolved oxygen concentration, and T = 30°C. The enzymes used were glucoamylase (R. delemar), glucose oxidase (A. niger), and gluconolactonase (A. niger), all of which are important commercial biocatalysts, and a disaccharide was employed as the starting substrate. This study includes the basic kinetic properties of individual enzymes and interactions between components of the reaction mixture. Classical Michaelis-Menten single substrate or two substrate kinetic with parameters based on initial rate data predict correctly the batch time course of the sequential reaction network.
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• 38
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 211-218
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A new mechanochemical method for enzyme immobilization has been elaborated. The principle of this method consists of the following precepts. Partially hydrolyzed nylon fiber, the surface of which is known to be strewn with micro-cracks, is reversibly stretched (∼25%) and placed into an enzyme solution. Then, in the same solution, the fiber is made to relax and is taken out. The fiber retains considerable enzymatic activity even after numerous thorough washings (in a similar procedure without fiber stretching, equivalent washing removed all the enzymatic activity from the fiber). Immobilization on the fiber proceeds due to trapping of enzyme molecules by the microcavities on the surface of the support. The catalytic activity of mechanochemically immobilized chymotrypsin and trypsin is commensurable with their activity on covalent immobilization on nylon (calculated per unit of the macrosurface). A wide range of commercial polymers may be made of use as supports in the mechanochemical method of immobilization.
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• 39
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 247-265
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Pressure drop, gas hold-up, and oxygen transfer were investigated in a sieve tray column, a column with Koch motionless mixers, and a bubble column. The oxygen transfer experiments were conducted using cocurrent flow of gas and liquid under steady-state conditions with oxygen transfer from the gas to the liquid phase. The oxygen transfer rates and efficiencies of the sieve tray column and the column with Koch mixers were found to be superior to those of the conventional bubble column. Gas hold-up was also greater when sieve trays or Koch mixers were inserted in the tower. The pressure drop was found to be primarily due to the liquid head in all three columns.
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• 40
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 349-364
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Some properties of a number of enzymes immobilized by the diazotized m-diaminobenzene (dDAB) method are described. The pH-activity profiles of β-D-glucosidase, glucoamylase, peroxidase, uricase, and D-glucose oxidase were virtually unchanged on immobilization while those of catalase and dextranase were significantly altered. β-D-Glucosidase, glucoamylase, and glucose oxidase were found to be more susceptible to denaturation on lyophilization when immobilized than in the native state; however, sorbitol had a marked protective effect in every case examined. Sorbitol was also found to exert a stabilizing effect when lyophilized immobilized preparations were stored. Immobilization marginally improved the stabilities of a number of enzymes to heating at 60° at pH 8.0. The usefulness for continuous reaction of a column of glucoamylase attached to celite was established. The reuse of the solid supports was demonstrated.
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• 41
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 387-397
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Saccharomyces cerevisiae cells, Kluyveromyces marxianus cells, inulase, glucose oxidase, chloroplasts, and mitochondria were immobilized in calcium alginate gels.Ethanol production from glucose solutions by an immobilized preparation of S. cerevisiae was demonstrated over a total of twenty-three days, and the half-life of such a preparation was shown to be about ten days.Immobilized K. marxianus, inulase, and glucose oxidase preparations were used to demonstrate the porosity and retraining properties of calcium alginate gels.Calcium alginate-immobilized chloroplasts were shown to perform the Hill reaction.Some experiments with immobilized mitochondria are reported.
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• 42
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 435-438
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 43
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 439-442
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 44
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 493-505
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Oxygen transfer from gas to liquid under steady-state cocurrent flow conditions was modeled using the dispersion model, and the oxygen transfer coefficients were estimated from available data for a column with Koch motionless mixers. The dispersion in the column was estimated for several different gas and liquid flow rates using steady-state tracer experiments. The estimated oxygen transfer coefficients were compared with those estimated using complete mixing and plug flow models. The results indicate that the dispersion model is the most appropriate model for estimating the mass transfer coefficient from the available data.
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• 45
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 555-555
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 46
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 557-559
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 47
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 583-589
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 48
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 605-610
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 49
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 649-660
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: On the basis of elastic waves released by imploding cavitation bubbles, a mechanism for biological cell disintegration in high intensity ultrasounds has been proposed. Comparison of this mechanism with the published results on yeast cells shows many points of agreement suggesting that yeast cell disintegration in ultrasonic cavitation occurs by shear stresses developed by viscous dissipative eddies arising from shock waves.
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• 50
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New York, NY [u.a.] : Wiley-Blackwell
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 51
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 661-682
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The effect of dispersed n -dodecane or n -hexadecane on the air-to-aqueous phase overall volumetric oxygen transfer coefficient in a simulated (cell-free) stirred-tank fermentor is described. The oil volume fraction ranged from zero to 0.10; the ionic strength of the aqueous phases was varied from 0 to 0.45. The air-to-aqueous phase coefficients in both oil-free (KLa) and oil-bearing (KLa*) systems were evaluated from unsteady-state experiments using a membrane-covered probe to follow the aqueous phase dissolved oxygen tension.For all systems studied, KLa*/KLa was found to be independent of P/V and vs for all practical purposes. However, for a particular aqueous phase and at a given P/V and vs, the ratio KLa*KLa generally differed from unity. Depending on the combination of hydrocarbon type and volume fraction and the aqueous-phase ionic strength employed, the dispersed hydrocarbon may, in some cases, reduce the rate of oxygen transfer and in others enhance it relative to that of the corresponding oil-free gas-liquid dispersion. Enhancement of the air-to-aqueous transfer rate by such negative spreading coefficient hydrocarbons has not been reported previously.
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• 52
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 727-740
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The microbiological oxidation of ferrous iron in batch and continuous systems has been investigated in relation to uranium extraction from a low-grade ore by Thiobacillus ferrooxidans. The influence of the parameters, agitation, and aeration on oxygen saturation concentration, rate of oxygen mass transfer, and rate of ferrous iron oxidation was demonstrated. The kinetic values, Vmax and K were determined using an adapted Monod equation for different dilution rates and initial concentrations of ferrous iron. The power requirements for initial leaching conditions were also calculated. Uranium extraction as high as 68% has been realized during nine days of treatment. Regrinding the leach residue and its subsequent leaching yielded 87% uranium solubilization.
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• 53
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 377-385
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Enzymatic hydrolysis of the cellulose in raw primary settled municipal sludge by Trichoderma viride cellulase achieved conversions of up to 75% of the cellulose, primarily to cellobiose, in 24 hr. Simultaneously the gel-like characteristic of raw primary sludge was changed to that of a slurry of fine particles in less than 2 hr, causing a radical change in the ability to ultrafilter the sludge.The use of raw primary sludge as a growth medium for T. viride cellulase production was also investigated. It was possible, with nitrogen supplements, to obtain an enzyme with a filter paper activity (FPA) of two compared to over four which is attainable on defined medium of similar strength.The potential use of cellulase treatment as a pretreatment or integral part of waste treatment processes is discussed and the alternatives evaluated.
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• 54
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 801-819
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Rates of CO2 desorption from fermentation broths under actual operating conditions were determined by measuring the CO2 partial pressure in the exit gas. The concentrations of CO2 physically dissolved in the broths were measured by the so-called tubing method. Values of kLa for CO2 desorption calculated from these values agreed well with the kLa values for oxygen absorption corrected for the difference in gas diffusivities. The dissolved CO2 concentration in the broth, which seems to bean important operating parameter, can easily be estimated from the CO2 partial pressure in the exit gas, a more easily measurable quantity, if the kLa value is known. For a given value of kLa, assumption of perfect mixing or plug flow in the gas phase made little difference in the calculated values of the dissolved CO2 concentration, indicating that the gas phase was probably in between perfect mixing and plug flow.In industrial fermentors, the CO2 partial pressure in the exit gas can practically be assumed to be in equilibrium with the dissolved CO2 concentration.
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• 55
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 841-851
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The procedure and apparatus for the continuous coagulation of yogurt are described. The continuous coagulation takes place in a plug-flow fermentor. Prefermented milk is brought into this fermentor with the help of a centrifugal distributor, which avoids any undesirable mixing of the prefermented milk with the acidifying milk. A special stirring plate allows a stirring treatment in the coagulation tank. By this procedure the acidity and the viscosity of the final yogurt can be controlled between certain limits. The organoleptic characteristics of the continuous manufactured yogurt are good.
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• 56
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Biotechnology and Bioengineering 19 (1977), S. 821-839
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The principles of a method for the continuous manufacture of yogurt, based upon a two stage system, are given. The first stage, the prefermentation of milk at 45°C to a pH of 5.7, is described.The limitations of this continuous prefermentation are experimentally determined. No change in the balance of the yogurt bacteria, Lactobacillus bulgaricus and Streptococcus thermophilus, was observed. A mathematical approach is given for starting and stopping the process.
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• 57
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Biotechnology and Bioengineering 19 (1977), S. 853-865
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: A new method to estimate the oxygen transfer coefficient (KLa) from the experimental dynamic response data is presented. Employing a linear model which allows for gas phase, diffusion film, and oxygen electrode dynamics, the first moment of the response curve is simply related to the sum of the model parameters. Two separate experiments are used to characterize the measurement dynamics and to measure the unknown KLa parameter. The simple calculation procedure involves only measuring the area above the response curves.
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• 58
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Biotechnology and Bioengineering 19 (1977), S. 901-921
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: We have demonstrated that a simple electrochemical cell can serve as a detector of NADH concentration in a flow system thereby providing an assay technique for NADH dependent enzymes. When this is applied to NADH produced by enzymatic reaction, then a reproducible measure of enzyme activity is obtained. This method of enzyme activity assay is applicable to a number of oxidoreductase enzymes which employ NAD+ or NADP+ as coenzymes to achieve substrate modification. The presence of electroactive species in samples of human serum has proved a serious problem in the electrochemical analysis of serum activity. These species produce a large background anode current at the anode voltage appropriate for NADH oxidation. The presence of this high current limits the usefulness of amplification of the current output to detect small changes in NADH concentration.
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• 59
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 933-935
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
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• 60
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 941-958
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Continuous culture studies have been carried out growing Trichoderma viride QM 9123 in a 10 liter stirred fermentor on a medium containing commercial glucose as the carbon source. Experiments were carried out at 30°C and at three controlled pH values of 2.5, 3.0, and 4.0, over a range of dilution rates from 0.01 to 0.11 hr-1. Steady-state values of cell, glucose, and cellulase concentration oxygen tension, and outlet gas oxygen partial pressure were recorded. Values of maximum specific growth rate, endogenous metabolism coefficient, Michaelis-Menten coefficient, yield and maintenance coefficient for glucose were derived and correlated the effect of the hydrogen ion concentration. Specific oxygen uptake rates were correlated with specific growth rates and absorption coefficients were shown to be a function of dilution rate independent of pH. Some data on cellulase biosynthesis were examined and correlated in terms of a maturation time model.
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• 61
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Biotechnology and Bioengineering 19 (1977), S. 983-1008
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The response of a polarographic oxygen electrode to a step change and to an exponential change in bulk oxygen concentration was studied theoretically and experimentally for the case where there is a significant liquid film resistance at the outerside of the membrane-covered electrode. The probe response has been described considering the start-up period of the concentration changes (the period of time that will elapse before the new concentration level is established and/or before the volumetric mass transfer coefficient kLa regains its steady-state value after the gas supply is opened to the fermentor). A linear change of the pertinent characteristics is assumed during this start-up period. It is shown that a substantial error could be introduced by neglecting the start-up period for cases frequently occurring in practice. In addition, the dependences of the probe response on the direct contact of bubbles with an electrode and on the fluid flow field around it were discussed.
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• 62
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1087-1090
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
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• 63
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 1037-1063
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: The overall rate of reaction of a gel-immobilized urease particle necessarily depends upon the hydrogen ion concentrations within the particle. When the particle is unbuffered, the internal hydrogen ion concentrations are a consequence of the local rates of reaction and the rate of egress of the products of hydrolysis. A simple apparatus has been devised which allows a fairly rapid determination of the hydrogen ion concentration in the center of a particle for any given size, enzyme concentration, substrate concentration, and external pH. The products of urea hydrolysis are self-buffering in the region of pH 8.83 and for an external pH less than the self-buffering pH, the pH within the particle is increased because of the reaction. When the external pH is greater than the self-buffering pH, the converse occurs. The pH at the center of the particle approaches the self-buffering pH with an increase in particle size and enzyme concentration. The external pH necessarily differs in effect when above or below the self-buffering pH. An increase in the external substrate concentration has a limited effect, simply rendering the local rates of reaction to be of zero order. The center-line pH and therefore all internal hydrogen ion concentrations depend upon the parameter \documentclass{article}\pagestyle{empty}\begin{document}$L\sqrt {\rho _e}$\end{document} and the external pH. Differences between the external and center-line pH values of the order of units are unexceptional. The implications of the internal pH profiles on the local and overall rates of reaction are explored.
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• 64
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New York, NY [u.a.] : Wiley-Blackwell
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
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• 65
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 937-937
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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• 66
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New York, NY [u.a.] : Wiley-Blackwell
Biotechnology and Bioengineering 19 (1977), S. 959-981
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Three distinct cellobiase components were isolated from a commercial Trichoderma viride cellulase preparation by repeated chromatography on DEAE cellulose eluting by a salt gradient. The purified cellobiase preparations were evaluated for physical properties, kinetics, and mechanism. Results from this work include: (1) development of a one step enzyme purification procedure using DEAE-cellulose; (2) isolation of three chromatographically distinct, yet kinetically similar, cellobiase fractions of molecular weight of ∼76,000; (3) determination of kinetics which shows that cellobiase hydrolyzes cellobiose by a noncompetitive mechanism and that the product, glucose, inhibits the enzyme, and (4) development of an equation, based on the mechanism of cellobiase action, which accurately predicts the time course of cellobiose hydrolysis over an eightfold range of substrate concentration and conversions of up to 90%. Based on the data presented in the paper, it is shown that product inhibition of cellobiase significantly retards the rate of cellobiose hydrolysis.
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• 67
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Biotechnology and Bioengineering 19 (1977), S. 1019-1035
ISSN: 0006-3592
Keywords: Chemistry ; Biochemistry and Biotechnology
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
Notes: Ethanol production by Kluyveromyces fragilis and Saccharomyces cerevisiae was studied using cottage cheese whey in which 80 to 90% of the lactose present had been prehydrolyzed to glucose and galactose. Complete fermentation of the sugar by K. fragilis required 120 hr at 30°C in lactase-hydrolyzed whey compared to 72 hr in nonhydrolyzed whey. This effect was due to a diauxic fermentation pattern in lactase-hydrolyzed whey with glucose being fermented before galactose. Ethanol yields of about 2% were obtained in both types of whey when K. fragilis was the organism used for fermentation. Saccharomyces cerevisiae produced alcohol from glucose more rapidly than K. fragilis, but galactose was fermented only when S. cerevisiae was pregrown on galactose. Slightly lower alcohol yields were obtained with S. cerevisiae, owing to the presence of some lactose in the whey which was not fermented by this organism. Although prehydrolysis of lactose in whey and whey fractions is advantageous in that microbial species unable to ferment lactose may be utilized, diauxie and galactose utilization problems must be considered.