Antifungal screening of bioprotective isolates against botrytis cinerea, fusarium pallidoroseum and fusarium moniliforme

Abstract

The fungi Botrytis cinerea, Fusarium pallidoroseum, and Fusarium moniliforme are the causative agents of several plant diseases and can cause significant crop loss both before and after harvest. Fungicides are employed to control these phytopathogens, but fungicide use has led to an increase in resistance and may negatively affect the environment and human health. Hence, more environmentally sustainable solutions such as biological control methods are needed. The purpose of this study was to screen 22 bacterial isolates for inhibitory activity against fungal phytopathogens. To evaluate antifungal activity, the bacterial isolates were individually spot-inoculated onto Tryptic Soy Agar or de Man, Rogosa, Sharpe agar, and then a plug of fungal-colonized agar was placed onto the center of the isolate-inoculated plate. Plates were incubated at 24 ◦ C for 10 days and fungal growth was evaluated. Nine of the 22 isolates screened inhibited all three fungi; inhibition by these isolates ranged from 51–62%, 60–68%, and 40–61% for B. cinerea, F. pallidoroseum, and F. moniliforme, respectively. Isolates were also screened for biosurfactant activity using the drop-collapse test. Bacillus megaterium, Bacillus coagulans, Bacillus thuringiensis and three Bacillus amyloliquefaciens isolates demonstrated strong biosurfactant activity and suppression of all three fungi, and therefore are recommended for further study.