Influence of culture conditions on the cell yield and amylases biosynthesis in continuous culture by Schwanniomyces castellii

Abstract

Schwanniomyces castellii excreted α-amylase and amyloglucosidase into the medium in the presence of starch. The biosynthesis and the rate of excretion were influenced by dissolved oxygen (specially for α-amylase), pH of the culture and dilution rate. The cell yield observed (0.59) remained constant up to D=0.35h-1 with starch as substrate. But in the case of growth on glucose, the yield observed was equal to 0.62 up to a dilution rate of D=0.18 h-1. Beyond this value Y x/s decreased and ethanol was produced. The onset of fermentation dependend partly on the nature of the substrate and not only on the environment in particular on the quantity of dissolved oxygen present.