In a population of the productive Bacillus subtilis strain the production of alpha-amylase differentiates at the cell level. Individual cells in the population were analyzed and the production of isolates was tested. The mean specific activity of alpha-amylase in the productive group after the isolation was 5.0 U/mg dry substance and in the nonproductive group 1.5 U/mg dry substance. This ratio remained unchanged during long-term observations and after repeated transfers. In selected strains of both groups the specific growth rate was determined in a synthetic medium containing various amounts of casein hydrolyzate. The detected differences in the growth rate between the productive and the nonproductive clones are determined by amino acid concentration.

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Production of extracellular enzymes in continuous culture