Bioefficacy of Bacillus subtilis against Aspergillus flavus, the cause of aflatoxin contamination in chilli

Abstract

Bacillus subtilis a gram positive, endospore forming bacteria play a major role in biocontrol and PGPR activities. Thirty isolates of B. subtilis were obtained from different rhizosphere soil samples from different parts of North Eastern Karnataka region. All the isolates were rod shaped, positive for gram reaction, endospore, oxidase, catalase, starch hydrolysis, negative for indole, KOH test and green coloured colonies were grown on Hichrome Bacillus agar medium. All the isolates showed varied levels of antagonist activity in vitro against major pathogens of chilli. In vitro screening of B. subtilis (30 isolates) against A. flavus which causes the aflatoxin contamination. The varied levels of inhibition of mycelial growth of aflatoxin fungus was obtained. Among different isolates BS22 showed maximum 40.96 percent inhibition followed by BS5 was 38.88 percent and minimum was17.50 percent in case of BS29 as compared to control. The B. subtilis strains were isolated, identified and used in this present study is a promising natural bioagent which can be considered as an alternative to chemical pesticides in chilli disease management strategies and also used in integrated disease management.