Production of biomass and amylases by the yeast Lipomyces kononenkoae in starch-limited continous culture

Summary: In strain IGC 4052 of the amylolytic yeast Lipomyces kononenkoae growing in starch-limited chemostat cultures the critical dilution rate was reduced to about half of its theoretical value due to severe catabolite repression of amylase formation while its value in a repression-resistant mutant was near its theoretical value. The enzyme yield coefficients and the specific production rates of α-amylase and glucoamylase passed through maxima at intermediate dilution rates. The shapes of the respective curves were partly determined by catabolite repression (parent strain) or its absence (mutant strain) while induction did not seem to play to role. An additional growth-linked regulatory mechanism seemed to be involved. The use of continuous culture as compared with batch culture, increased the maximum biomass productivity by a factor of 2.2 in the mutant strain and by a factor of 1.4 in the parent strain.