摘要:

AbstractIn the course of submerged cultivation of low‐production and industrial production strains ofStreptomyces aureofaciens, the activity of enzymes of the tricurboxylic acid cycle was studied. The activities of citrate synthase (EC 4.1.3.7), aconitate hydratase (EC 4.2.1.3), isocitrate dehydrogenase (EC 1.1.1.42), fumarate hydratase (EC 4.2.1.2), and malate dehydrogenase (EC 1.1.1.37) were estimated spectrophotometrically in cell‐free preparations. In the growth phase, mainly the initial reactions of the cycle were active with both strains. In production‐phase, the activities of enzymes in the low‐production strain were 2–5 × higher than in the production strain. Benzylthioeyanate, at a concentration of 5 × l0−5M, stimulated chlortetracycline production of both strains with accompanying decrease in activity of the enzymes of the tricarboxylic acid cycle. The role of the tricarboxylic acid cycle in control of chlortetracycline biosynthesis

ISSN:0006-3592    

DOI:10.1002/bit.260110402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractAn oxygen probe is developed, using the principle of the silver‐lead galvanic cell, covered with a plastic membrane. It is steam sterilizable while filled with water; after sterilization, water is easily exchanged for the electrolyte, potassium bicarbonate. Flat plastic membranes up to a thickness of about 0.1 mm can be applied. The membrane is secured and stretched in a special way, which guarantees a leakproof seal. The outer shape of the probe has a tulip‐form and consists of polished stainless steel, except for the electrode face. The electrode is suitable for laboratory and industrial use and its components are completely standardized.Almost linear response for O2‐partial pressures up to atmospheric is obtained with 0.001 in. and 0.002 in. FEP‐Teflon membranes. 90% response time is of the order of 10–15 sec for the 0.001 in. membrane, Residual current is almost negligibl

ISSN:0006-3592    

DOI:10.1002/bit.260110403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractDissolved oxygen and glucose concentrations have been independently maintained at various concentrations for extended periods during growth ofCandida utilisin continuous culture. Simultaneous observations of cytochrome concentration, growth rate, rates of uptake of oxygen and glucose and rates of production of CO2, ethanol and acid have been made during steady states at various levels of oxygen and glucose. There is an inverse relationship between dissolved oxygen and cytochrome and between glucose cocentration and cytochrome.Studies of the transient state following a step change from high to low dissolved oxygen show that there is a lag of about 10 hr during which there is no change in the above parameters. This is followed by rapid oscillatory changes in cytochrome content and a change to a more fermentative metabolism.

ISSN:0006-3592    

DOI:10.1002/bit.260110404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260110405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThis paper illustrates the type of conclusions which may be reached by the use of an electrode for measuring oxygen tension in fermentation broths. The critical oxygen level, based on oxygen uptake, and the minimum oxygen tension necessary for maximum antibiotic synthesis for two commercial antibiotic fermentations, capreomycin and cephalosporin C, were studied. Capreomycin yields were depressed at an oxygen tension which was slightly below the critical oxygen level. Cephalosporin C synthesis was depressed at an oxygen tension higher than the critical oxygen level.

ISSN:0006-3592    

DOI:10.1002/bit.260110406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractTotal lipids were extracted from the cells ofCandida utilisgrown at a constant population density in continuous culture. At different steady states, the environment was controlled with respect to dissolved oxygen and glucose concentrations, pH and temperature. Gas liquid chromatography was used to follow quantitative and qualitative changes in the fatty acid composition of the cells. Increasing glucose concentration resulted in higher lipid content; high oxygen concentrations increased the level of polyunsaturated fatty acids. The most significant changes in fatty acid composition took place when both glucose and oxygen concentrations were high, and under these conditions the amount, of linolenic acid was at its highest value.

ISSN:0006-3592    

DOI:10.1002/bit.260110407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe oxygen transfer coefficient has been investigated inS. noursciandS. lavendulaefermentation broths obtained from fermentors of different operating volumes (61., 30001., 20,0001.). Fermentors hadKLasvalues ranging from 1.0 to 17.0 min−1, calculated from sulphite oxidation rates. The dynamic measurement of the volumetric oxygen transfer coefficient. (KLa) has been performed in the different fermenting systems. As the fermentation progressed, especially in the first stages,KLa values have decreased in both fermentations and in each system of fermentors. In order to characterise the whole fermenting system an averageKLaswas calculated from the obtainedKLa values. The averageKLa grew with increasingKLasvalues and ranged from 0.03 to 3.72 min−l. Some factors possibly having an influence on the, change ofKLa have been studied.The oxygen transfer coefficients of the broths have been measured in falling films and ranged from 0.05 to 0.4 cm min−1. The flow conditions have been characterized by Reynolds numbers of broths varying between 1.0 and 60.0. The average thickness of the falling films have been measured and plotted against Reynolds number. The Re+which is the breaking‐point of the plot increased as the fermentation proceeded. In the region of Re+the values of the oxygen transfer coefficient increased rapidly. An approximate correlation could be established between the Re+and the physical properties of fermentatio

ISSN:0006-3592    

DOI:10.1002/bit.260110408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractOn increasing aeration rate in chemostat cultures ofE. colithe redox potential (Eh) of the culture changes from −l50 mv to +250 mv. During this period only a slight increase in measured dissolved oxygen concentration is observed.It is suggested thatEhbe used as a control variable for aeration in the oxygen limited growth condition, whilst dissolved oxygen concentration be used as control variable in the presence of excess oxygen.Change in cytochromeb1, three tricarboxylic acid cycle enzymes and hydrogenase can be related to cultureEh. These changes are discusse

ISSN:0006-3592    

DOI:10.1002/bit.260110409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractIn beer fermentation, yeast cells are kept in suspension, despite their higher density, by natural agitation created by ascending CO2bubbles. Yeast cells are unable to nucleate bubbles but instead release CO2in a soluble form in such a way that the medium tends to become supersaturated.A higher concentration of yeast cells and the presence of solid particles cause the formation of bubbles at the bottom of the fermenter and practically only there. The rising bubbles grow and accelerate by sweeping the CO2formed throughout the fermenter by the suspended yeast cells, thereby creating a fluid regime. A mathematical expression relating the bubble agitation power to the fermentation parameters was obtained and used to design more efficient fermenter shapes.

ISSN:0006-3592    

DOI:10.1002/bit.260110410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe presence of microorganisms have been shown to increase by over 40% the mass transfer rates from small oxygen bubbles at low Reynolds number flow. This increase was found to be due only to the microbe cells as inert particles disrupting the quasi‐static liquid surface film surrounding the gas bubble and thus decreasing the gas‐liquid interfacial resistance. The observed increase in oxygen mass transfer rates was not dependent on cell viability, no effect was noted due to cell‐liquid interfacial resistance, nor was the phenomenon due to altering the physical properties of the liquid during cell propagation. These results were obtained in a unique plexiglass apparatus designed for observing under a microscope a small (0.4 mm dia.) stationary oxygen bubble collapsing into a flowing fluid. The oxygen bubble was injected by a small hypodermic needle and the fluid was suspensions of the yeastCandida intermedia, the bacteriumPseudomonas ovalis, 0.3μ alumina, as well as base points of cell free broth and pure water. Several well‐known chemical inhibitors of oxidative phosphorylation were used to limit cell oxygen uptake. Calculations of oxygen mass transfer rates were compared with the semi‐empirical model of Frössling, the circulating sphere model of Levich, and the rigid sphere concentration boundary layer model of Fried‐lander, the latter two showing strong Reynolds number dependence that may be due to radial

ISSN:0006-3592    

DOI:10.1002/bit.260110411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY