P163: Examination of Bacillus biological control agents for extracellular chitinase and protease activities

Fusarium head blight (FHB) of wheat and barley, caused by Fusarium graminearium is of global concern. Disease management of FHB can be done in several ways, including using disease-resistant cultivars and biological control agents (BCAs).  Our studies of biological control of FHB using Bacillus amyloliquefaciens strains indicate that, in addition to bacterial lipopeptide biosurfactants, other bacterial products may be involved. We hypothesized that the Bacillus BCA strains exhibit extracellular chitinase and protease activities in addition to lipopeptide production.   Plate and broth-based assays were done to analyze the ability of BCA strains to produce chitinase and protease. Very minimal growth of the BCAs was observed on 2% colloidal chitin agar; and they exhibited slight chitinase activity in Remazol Brilliant Blue-labeled colloidal chitin broth.  On Tryptic Soy Agar amended with colloidal chitin, BCA growth was observed at different incubation temperatures; but no clearing zones were observed.  Protease activity was observed on skim milk agar; while minimal or no protease activity was observed in a tryptic soy broth (TSB) formulation; and all strains were gelatinase positive.   There were differences among the strains for both chitinase and protease activity.   Since BCA protease activity was minimal in the TSB formulation, future work should check their protease activity at different time intervals in other broth formulations that may be sprayed onto grain heads to control FHB.  Further, it might be essential to check the activity of chitinase and protease on the growth of Fusarium graminearium in-vitro.