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  • 1
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Direct interfacing of a membrane based mass spectometer separator to an aqueous solution of water-saturted gas stream allows continuous monitoring of a vareity of dissolved volatile compunds. Even if the solution is saturated with atmoshpheric gases, we demonstrate that deuterated water concentration in aqueous solution can be measured over concentration ranges of interest to physiological studies, with an estimated, extrapolated detection limit less than the natural abundance.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Measurement of chemical concentrations is a weak link in the monitoring of fermentations. The use of a computer-controlled mass spectrometer (MS) has made possible the measurement of one or more volatile compounds on an essentially continuous basis, both in the liquid (broth) and the gas (headspace) phases. For our purposes, the MS was used, not as a spectrometer for chemical identification, but as a programmable detector for measuring concentrations of different compounds. Specifically, a computer-controlled MS was employed during the fermentation of Saccharomyces italicus, to monitor N2, O2, and CO2 concentration in the gas phase, and N2, O2, CO2, and ethanol in the liquid phase. The performance of the MS was carefully analyzed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This work describes the recovery of an extracellular alkaline protease from fermentation broths of a Bacillus sp ATCC 21536, at pH=10.0 using ultrafiltration (MWCO 100,000) and microfiltration (0.1 μm) membranes in hollow fiber devices. The influence of membrane pore size and polymeric material and membrane filtration performance was studied. High protein recoveries and high average flux rates were obtained with polysulfone membranes. A decrease of concentration polarization was obtained, simultaneously with enhancement of filtration flux rate and enzyme recovery by using submicron sized charged particles. These polymers lead to flocculation and adsorption of whole cells and soluble factors from the fermentation broth. The best results were obtaiend by combination of cationic (0.1%) and anionic (0.04%) polymers.
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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 production of penicillin amidase fromBacillus megaterium ATCC 14945 was examined in a sulfur-limited chemostat. Below 50% of the maximum growth rate, enzyme production was independent of dilution rate; above this point production decreased as growth rate increased. A simple and defined medium forBacillus licheniformis 749/C was developed, and extracellular penicillinase production was studied in a chemostat under sulfur- and nitrogenlimited conditions. While the yield of this enzyme differed little between these growth-limiting conditions, the specific activity of the penicillinase per unit weight of extracellular protein was increased 50% under nitrogenlimited conditions. Furthermore, the proportion of extracellular enzyme was greater in continuous, than in batch culture.
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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 dynamic calorimetric technique was investigated to determine the feasibility of monitoring cell growth by thermal measurements. Theoretical analysis of growth ofSaccharomyces cerevisiae on glucose showed that the correlation depends on cellular yield values but not on ethanol formation. Experiments withS. cerevisiae on a molasses-mineral salts medium resulted in a thermal yield of 4.4 kcal/g cells, consistent with our theoretical expectations.
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  • 6
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effect of various carbon, nitrogen and sulfur sources on the production of heparinase by Flavobacterium heparinum in defined medium in the presence and absence of heparin as the inducer has been studied. Carbon catabolite repression has been observed in defined medium containing one of several carbon sources including simple sugars, alcohols and organic acids. Fed batch fermentations result in 10 g/l of cells and heparinase titers as high as 100,000 U/l by avoiding carbon catabolite repression. Growth on heparin as a sole carbon source resulted in both a high growth rate of 0.12 h−1 and a high specific activity of 18 U/mg. Specific heparinase activity was markedly reduced when the end products of heparin catabolism were used as carbon, nitrogen or sulfur sources in defined medium. In defined medium with a low sulfate concentration, of less than 10−3 M, specific activities as high as 8 U/mg have been observed even in the absence of the normally required inducer, heparin.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 333-348 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methanol oxidase produced by the yeast Hansenula polymorpha DL-1 was used for the enzymatic oxidation of methanol to formaldehyde. The kinetics of enzyme and protein release during cell desruption were studied at the laboratory scale with a Braun homogenizer and the pilot plant scale with a Manton-Gaulin homogenizer. Conditions were defined for maximum release and retention of high activity in cell-free extracts. Methanol oxidase was immobilized by adsorption on DEAE-cellulose from enzymes in cell-free extracts or from ammonium sulfate purified purified fractions. The kinetics of formaldehyde formation with both soluble and immobilized enzyme was studied in batch and continuous reactors.
    Additional Material: 9 Ill.
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  • 8
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel means of extracting carboxylic acids from aqueous solutions is described which involves the use of a lipolytic enzyme to convert the acid to a more hydrophobic ester. A water-immiscible long-chain alcohol serves both as a reactant in esterifying the acid, and as a solvent for extraction of the ester. Radiochemical tracer studies of the underlying reaction and extraction equilibria established that a low equilibrium concentration of ester (0.04-0.5mM) in the presence of water is counterbalanced by the high distribution coefficient of the ester (220-3380, wt. basis). The net result is a substantial (4- to 15-fold) increase in the apparent distribution coefficient of the acid; 80%-95% of the extracted acid is in the esterified form. The method is applicable to a variety of alcohols and acids.
    Additional Material: 3 Ill.
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  • 9
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A procedure for measuring the rate of heat production from a fermentation has been developed. The method is based on measuring the rate of temperature rise of the fermentation broth resulting from metabolism, when the temperature controller is turned off. The heat accumulation measured in this manner is then corrected for heat losses and gains. A sensitive thermistor is used to follow the temperature rise with time. This procedure is shown to be as accurate as previous methods but much simpler in execution. Using this technique, the rate of heat production during metabolism was found to correlate with the rate of oxygen consumption. Experiments were performed using bacteria (E. coli and B. subtilis), a yeast (C. intermedia), and a mold (A. niger). The substrates investigated included glucose, molasses, and soy bean meal. The proportionality constant for the correlation is independent of the growth rate, slightly dependent on the substrate, and possibly dependent On the type of organism growth. This correlation has considerable potential for predicting heat evolution from the metabolism of microorganisms on simple or complex substrates and providing quantitative parameters necessary for heat removal calculations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillin amidase, an enzyme which hydrolyzes benzylpenicillin to 6-aminopenicillanic acid and phenylacetic acid, is produced by Bacillus megaterium ATCC 14945 as an extracellular enzyme. We used this system as a model to examine the effects of nitrogen, sulfur, and phosphorous limitation on enzyme production in continuous culture. For these studies, we developed a minimal medium for B. megaterium which contained histidine as the sole nitrogen source. Batch experiments showed that this enzyme is produced as a growth-associated metabolite. Enzyme production was shown to be a function of the growth-limiting conditions and the concentration of the inducer, phenylacetic acid. Sulfur limitation in continuous culture yielded enzyme activities approximately three to five times those observed in nitrogen- and phosphorous-limited chemostats. These results are discussed in terms of the environment's influence on enzyme production in continuous culture.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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