Summary: Synthesis of chitinase and chitosanase by the entomopathogenic fungus is regulated by products of chitin and chitosan degradation through an inducer-repressor mechanism. Slow-feeding with sugars or alanine (about 20 μg ml h) in a carbon deficient medium to prevent catabolite repression (restricted cultures) demonstrated that the most effective inducers of chitinase and chitosanase were the principal monomeric constituents of chitin (-acetylglucosamine) and chitosan (glucosamine) respectively. Increasing the rate of release of -acetylglucosamine decreased chitinase synthesis by about 87% while causing a sevenfold increase in growth. In batch cultures high chitinase activities were present only in chitin-containing medium. There was a negative correlation between accessibility and amount of chitin substrates, levels of free -acetylglucosamine in culture fluids and chitinase production. Addition of carbohydrates, lipid or proteins to chitin-grown cultures repressed chitinase production. Basal levels of chitinase were produced in non-inducing media. Production of chitobiase (-acetylglucosaminidase) was enhanced from high basal levels by amino sugars, but was less inducible and less susceptible to catabolite repression than chitinase.


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