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

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 vivo under 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.

Physiological Effects of Microbial Biocontrol Agents in the Maize Phyllosphere

“…[ 160 ] isolated glucanase-producing rhizobacteria from wheat-maize cropping systems to decrease Fusarium wilt in tomatoes. A pH-, temperature- and salinity-stable chitinase is produced by a strain of B. subtilis induced by the pathogen Botrytis cinerea [ 161 ]. Additionally, MBCAs can prime the host plant to produce these enzymes.…”

Modes of Action of Microbial Biocontrol in the Phyllosphere

“…Their importance in the rhizosphere indicates the potential of further studying the microbial chitinase activity on the phyllosphere. It has been demonstrated that B. subtilis J9 strain protects strawberry plants against B. cinerea in field conditions and that this strain produces extracellular chitinase and protease (Essghaier et al, 2012). Recently, we observed that certain lactobacilli can inhibit hyphae formation of fungi in vitro by producing bifunctional enzymes with chitinase/peptidoglycan hydrolase activity (Allonsius et al, 2019).…”