Abstract
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. Key words: Halotolerant Bacillus antifungal activities grey mold disease.
Highlights
The gray mold disease caused by Botrytis cinerea inflicts great economic losses for untreated strawberries (25%)
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 vivo under field conditions on strawberry
The current control method against B. cinerea in strawberry cultivation is the application of fungicides during flowering; but the agricultural sector that does not use pesticides for control of plant diseases is increasing and there is an urgent need for alternative methods
Summary
The gray mold disease caused by Botrytis cinerea inflicts great economic losses for untreated strawberries (25%). The current control method against B. cinerea in strawberry cultivation is the application of fungicides during flowering; but the agricultural sector that does not use pesticides for control of plant diseases is increasing and there is an urgent need for alternative methods. One of these methods is the use of preparations of microorganisms as biological means of controlling fungal diseases (Sutton and Peng, 1993).
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