ASPERGILLUS FLAVUS-INDUCED CHITOSANASE IN GERMINATING CORN AND PEANUTSEEDS - ASPERGILLUS-FLAVUS MECHANISM FOR GROWTH DOMINANCE OVER ASSOCIATED FUNGI AND CONCOMITANT AFLATOXIN PRODUCTION

Chitosanase, a new class of enzymes with antifungal properties was ind uced by toxigenic Aspergillus flavus in both germinating corn and pean ut seeds. The enzyme was partially purified and fractioned by SDS-Poly acrylamide Gel Electrophoresis activity and copolymerized with chitosa n or glycolchitosan as substrate, then quantified by scanning densitom etry and a 2-dimensional analysis software program. Chitosanase enzyme was markedly induced by toxigenic A. flavus growing in germinating co rn and peanut seeds, as compared to control (water) which showed the l owest activity (almost nil in corn). However, chitosanase induction wa s higher in seeds treated with chitosan from crustacea. Overall, enzym e activity was higher in peanut than in corn seeds. However, electroph oresed gels from peanut treated with A. flavus or water showed more po lypeptides (three and one, respectively) than gels from corn seeds, wh ich only showed one polypeptide for both A. flavus and water treatment . The enzyme molecular weight was estimated to be between 36 000 and 4 5 000.