Formation of Extracellular Enzyme Systems during the Growth of Geotrichum candidum3C on Cell Walls Isolated from Cereal Grain Coats

The activities of extracellular systems of hemicellulases, pectinases, and cellulases was studied during a 72-h cultivation of Geotrichum candidum3C. The culture was grown on a medium containing 3% cell walls isolated from wheat grain coats, which served as the sole carbon source. Enzymes catalyzing the degradation of pectin substances (beet pectin, -L-arabinan, and 1,4--D-galactan), as well as -D-galactosidase and -L-arabinofuranosidase involved in their hydrolysis, were formed first (4 h after the beginning of cultivation). Enzymes hydrolyzing 4-O-methyl--D-glucurono--D-xylan and sodium carboxymethyl xylan were also found in the culture liquid after 4 h of fungal growth. The contents of pectin-degrading and xylanolytic enzymes reached their maximum levels after 52–56 and 72 h of growth, respectively. Cellulolytic enzymes were detected after 8–28 h of cultivation. Enzymes degrading -D-galacto--D-mannan were found 24 h after the beginning of growth; their content was maximum after 72 h of cultivation.