In vivo and in vitro evaluation of antifungal activities from a halotolerant Bacillus subtilis strain J9

摘要

In this study, we aimed to identify the antifungal activities of the halotolerant?Bacillus subtilis?strain J9 under different carbon sources and salinity conditions?in vitro?and?in vivounder field conditions on strawberry. The strain J9 of?B. subtilis?was able to reduce grey mold disease on strawberry under field conditions with percentage reduction ranging from 46.3 to 44.3% which was comparable to those of chemical fungicides respectively after treatments of 8 and 40 days. Therefore, the strain J9 may be a good candidate for biological control. The strain J9 was able to produce high antifungal enzymes inducible by the pathogen; chitinase (102 U/ml), protease (14.5 U/ml) and laminarinase (0.74 U/ml). Furthermore, high halotolerant chitinase was detected in the culture supernatant under 0 to 25% NaCl (w/v). Interestingly, we described distinguishable characteristics of high activity and stability at different pH, temperatures of?B. subtilis?J9 chitinase. The analysis of the amino acid sequences coding to the putative catalytic domain from enzyme highlighted its relation to those of glycosyl hydrolase family 18.