Production of proteases by Fusarium species grown on barley grains and in media containing cereal proteins

The production of proteases by the cereal plant pathogens Fusarium culmorum , F. graminearum and F. poae was followed through seven days of cultivation . The fungi were grown in mineral and in gluten culture media, and on autoc laved barley grains. The proteolytic activities of each sample were analyse d at pH 2.2, 5.0 and 8.0 and the pH optima of the most active proteases wer e determined. All of the fungi grown in the gluten medium produced protease s that were active at pH levels between 6 and 10 and were most active at ab out pH 9.0. Fusarium poae also produced acid protease(s) with pH optima bet ween 3.0 and 3.5 when grown in the gluten medium. No protease activity was detected in the cultures that were grown in the mineral medium, except that a small amount was formed after the glucose substrate was depleted. When g rown on the barley grain medium the Fusarium species produced protease acti vities that were similar to the neutral and alkaline ones present in the gl uten cultures, but no pH2.2 protease activity was detected. The alkaline pr oteases had some characteristics that were similar to those of chymotrypsin . (C) 2000 Academic Press.