Einfluß alternierender Störungen auf die Verbrauchskennziffern beim Wachstum von Mikroorganismen

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The knowledge of the dependences of yield coefficients on milieu conditions and cell states is an important prerequisite for improving the economy of biotechnological processes for biomass production. The aim of the following investigation was the discovery of such regular relationships of microbial growth, the ingenious use of which can lead to increased yields by these processes.The influence of factors on yield coefficients is often described in the literature by material balances. But a detailed study of the yield coefficient dependences requires a consideration of energetic aspects, too. Recent investigations have shown that in addition to specific growth rate and yield Coefficients thermokinetic, biochemical, and morphological data are useful (MEYENBURG 1969, DAWSON 1972, THOMAS and DAW- SON 1977, SHAFOROSTOVA et al. 1973, HEINRITZ 1978, GLOMBITZA and HEINRITZ 1979, HEINRITZ and BLEY 1979. Thus, in addition to specific growth rate and yield also heat production, concentration of energy metabolites, concentration of functional cell constituents and morphological data were determined during growth processes.A representative example is the following: The yeastl) was cultivated aerobically and discontinuously in a laboratory fermentor on a glucose salt medium including 5% glucose. The cultivation volume was 5 litres and the aeration rate 80 litres per litre and hour. The salts of the fermentation medium were balanced for a biomass concentration of 30 grams dry weight per litre. To reach a high synchronization of microbial growth (BERQTER 1965, MEYENBURQ 1969) the inoculum was precultivated under the described conditions, and this was followed by a 24 hour incubation in a refrigerator.To obtain a quantitative characterization of aerobic yeast growth, the following data were determined : The biomass concentration was measured gravimetrically. The glucose concentration was determined photometrically using the phenole/sulfuric acid method (KORENMAN 1970). The ammonium nitrogen analysis was carried out according to KJELDAHL. The oxygen content of the effluent air was measured with a "Permolyt", the carbon dioxide content with an "Infralyt", both from VEB JUNKALOR, Dessau. The heat production was determined by a method which will be published in a following paper. The luciferine/luciferase reaction was used for ATP analysis (BACHI and ETTLINQER 1973). The NADH-concentration was analyzed by a sensitive ''cycling'' method (JACOBSON and JACOBSON 1976). Nucleic acids were extracted according to the method of SCHNEIDER (1945) and RNA was determined from the extinction a t 260 nm. The percentage of budding cells of the microorganism population was counted under the microscope.These are the results : The temporal dependence of biomass concentration, glucose concentration, and ammonium nitrogen concentration are represented in Fig. 1. These results deviate from the known functions of exponential growth.

Yield coefficients in dependence on milieu conditions and cell states. I. Synchronized batch growth of a yeast

Bley¹,

Heinritz²,

Steudel³

et al. 1980

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Yield coefficients in dependence on milieu conditions and cell states II. Influence of perturbations on continuous cultivation of the yeast Lodderomyces elongisporus on hydrocarbons

Heinritz¹,

Stichel²,

Bley³

et al. 1981

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The influence of perturbations on continuous yeast cell cultivations on hydrocarbons of crude oil is described.Due to such perturbations the fermentation system leaves its steady state, passes through transitional stages and reaches a new steady state. In the transitional stages a damped oscillation of biomass concentration, percentage of budding cells, oxygen consumption rate, and heat flow is observed. These results can be explained by partial synchronization of yeast cell functions in microorganism populations. I n phases of partial synchronization the cell cycle of a single cell is reflected by the behaviour of the microorganism population. The adaptationof the carbon substrate feeding rate to the state of partially synchronized microorganism population makes possible lower specific substrate consumption in biomass production.

Mikrobielle Verwertung von Mischsubstraten

Weide¹

1983

Decomposition of substrates by heterotrophic microorganisms is accomplished in natural biotopes soch as in soil and in waters, on or in macroorganisms but also in laboratory and industrial biotopes. The interest of man in these processes is manifold. Starting with the division of substrates into three groups of simple substrates, complex and mixed substrates with or without solid particles their qualitative and quantitative occurrence in nature and their significance in biotechnology will be discussed. In the decomposition of these substrates their utilization by pure cultures or mixed populations is t o be exactly distinguished. Simple growth curves, di-or polyauxy, sequences of decomposition of simple substrates of a mixed substrate, population changes and successions are only some of the phenomena occurring in this process. The pathways of catabolism are subjected to manifold regulations on the three levels of stoichiometrio regulation, the regulation of enzyme activity and the regulation of enzyme synthesis. In natural biotopes there is hardly a constant substrate supply over a longer period. That's why certain mechanisms of regulation are permanently acting. Thus the "normal" physiological state for microorganisms is characterized by permanent transition situationscalled "transients". These reactions are also applied to many biotechnological processes.