Cuticle-Degrading Proteases Produced by <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> and Their Induction in Different Media

Protease production by fourteen M. anisopliae isolates differing in geographical origin and host insect were investigated. Highest protease activity was observed during 4–8 days of culture incubation. Pr1 and Pr2 activity was investigated in various media containing different carbon and nitrogen source to evaluate the induction mechanism of these enzymes. Basal levels of Pr1 and Pr2 activity were observed in minimal medium suggesting constitutive production. Casein (1%) as an exogenous protein supplement was not able to induce significant release of Pr1 and Pr2 enzymes, whereas high levels of activity were observed in the medium containing colloidal chitin (2%) as sole carbon and nitrogen source. The pH, ammonia and oxalic acid production in in vitro conditions was also investigated and the alteration in pH for protease production was not significant in the different media used except for the medium containing casein (1%) as a supplement.