REGULATION OF EXTRACELLULAR PROTEASES IN ACHLYA-AMBISEXUALIS

The use of proteins as a nutrient source by Achlya ambisexualis was in vestigated, using media containing defined and undefined sources of ca rbon, nitrogen, and (or) sulfur. Release of extracellular proteases oc curred during growth on all proteins and protein hydrolysates tested, but not during growth on yeast extract or in defined medium. In gelati n-containing media, three major bands of extracellular protease activi ty were detected by electrophoresis, with estimated molecular mass of 26, 48, and 58 kDa. Growth on gelatin was stimulated to a much greater degree by the addition of glucose to the medium than by additions of glutamic acid or methionine. This and the release of ammonia during gr owth indicate that gelatin is less effective in meeting metabolic need s for carbon than it is in meeting the needs for nitrogen and sulfur. Protease secretion is only partially regulated by glucose, whereas glu cose, methionine, and glutamic acid in combination cause almost comple te repression. The pattern of regulation indicated by these results is most consistent with one of induction + derepression.