Cyclodextrin glycosyltransferase (CGTase) was released into the culture fluid by Bacillus macerans predominantly in the late stationary phase of growth and during autolysis in the presence of either glucose or starch as a carbon source. In both cases significant soluble intracellular enzyme activity could be observed in the early stationary phase, and a low non‐soluble intracellular CGTase activity could be demonstrated also in the exponential growth phase in the presence of starch. At the end of the exponential phase the non‐soluble specific intracellular enzyme activity was found to be constant with a value of 0.63 +/‐ 0.06 nkat/10(9) viable cells. Since amylase activity could not be detected in any intracellular or extracellular sample taken at any culture time, we conclude that cellbound CGTase is the only starch‐digesting enzyme in growing B. macerans and, hence, may be fully responsible for the degradation of starch in the culture fluid.
Valine coordinately increases the levels of three of the enzymes participating in the biosynthesis of isoleucine and valine in Mycobacterium pellegrino . The amount of valine required for end-product induction depends on the condition of the cells. Isoleucine inhibits the effect of valine. Acetohydroxy acid synthetase, the enzyme catalyzing the first common step in the biosynthesis of valine and isoleucine, is inhibited by valine. The induction effect of valine appears to be due to its ability to inhibit the activity of this enzyme, thus causing isoleucine deficiency, which in turn leads to derepression. This conclusion is supported by the fact that valine, under certain conditions, inhibits growth.
A Streptomyces griseocarneus strain was selected from 600 actinomyces tested to transform 3β,l7α,2l --trihydroxy-5-pregnen-20-one-3,21-diacetate into 17α,21--dihydroxy-4-pregnen-3,20-dione (compound Reichstein-S). This strain gave not only the highest yield of compound Reichstein-S, but the steroid transforming activity was not reduced in the presence of water immiscible organic solvents. This biosynthetic method, designed to obtain compound Reichstein-S by nonproliferating bacterium cells, has been patented (1).
Mycelial fragmentation in submerged cultures of the cephalosporin C (CPC) producing fungus Acremonium chrysogenum was characterized by image analysis. In both fed-batch and chemostat cultures, the proportion of mycelial clumps seemed to be the most sensitive morphological indicator of fragmentation. In a fed-batch fermentation culture, this declined from roughly 60% at inoculation to less than 10% after 43 h. Subsequent additions of glucose resulted in a sharp increase back to near the initial value, an increase that reversed itself a few hours after glucose exhaustion. Meanwhile CPC production continued to decline steadily. On the other hand, the addition of soybean oil enhanced CPC production, but had no significant effect on the morphology. Although it may sometimes appear that morphology and productivity are related in batch or fed-batch cultures, this study suggests that this is because both respond simultaneously to more fundamental physiological changes, dependent on the availability of carbon. In circumstances, such as supplementary carbon source addition, the relationship is lost. Chemostat cultures supported this belief, as CPC-production rates were hardly affected by the specific growth rate, but the morphology showed significant differences, i.e., lower dilution rates resulted in a lower proportion of clumps and in smaller clumps.Key words: image analysis, Acremonium chrysogenum, morphology, fragmentation, cephalosporin C.
The rate of penicillin formation in the medium containing lactose as sole carbon source markedly decreased after addition of glucose but at the same time the growth rate of fungal mycelium increased. Significant correlation was found between the formation of penicillin and the intracellular concentration of fructose-2,6-bisphosphate. It appears that penicillin production is influenced by the level of fructose-2,6-bisphosphate.
