In vitro antagonistic potential of bacterial endophytes against chilli anthracnose pathogen Colletotrichum acutatum

The escalating threat of chilli anthracnose and the adverse effects of chemical pesticides underscore the urgency for sustainable management of chilli anthracnose. This study aims to identify the potential endophytic bacteria as eco-friendly solutions to combat chilli anthracnose pathogen. Through evaluating their antagonistic effects, we aim to provide effective biological control strategies for this destructive plant disease. Among the 74 bacterial endophytes isolated from healthy chilli plants, Bacillus amyloliquefaciens (ENLB 4) exhibited the most pronounced antagonistic effect against the chilli anthracnose pathogen Colletotrichumacutatum. In vitro tests revealed that ENLB 4 inhibited the pathogen's growth by 56.43%. Additionally, the cell-free culture filtrate of ENLB 4 exhibited substantial inhibitory effects on pathogen growth at various concentrations (46.74% at 5%, 54.99% at 10%, and 63.55% at 15%, respectively). Similarly, volatile organic compounds produced by ENLB 4 resulted in a higher (37.78%) growth inhibition of the pathogen. Analysis of the culture filtrate using GC-MS identified 17 compounds, some of which possess antimicrobial properties (hexanoic acid, 3-Isobutylhexahydropyrrolo[1,2-a] pyrazine-1,4-dione, isovaleric acid), while others are known to induce systemic resistance in treated plants (acetic acid). These findings underscore the potential of endophytic bacteria, exemplified by B. amyloliquefaciens, as effective and environmentally friendly agents for disease management in agriculture.