In vitro and in silico analysis of the fungicidal potential of secondary metabolites from a bacterial endophyte against Botrytis cinerea

Bacterial endophytes are a rich source for the bioprospection of chemical compounds with biological activities for application as bio-fungicides. The potential fungicidal activity of secondary metabolites from Bacillus MHSD_36 was evaluated in vitro and in silico against Botrytis cinerea. The secondary metabolites showed both spore germination and mycelial growth inhibition against B. cinerea. In silico analysis confirmed the presence of gene clusters involved in the synthesis of secondary metabolites, from terpenes, beta-lactams and nonribosomal peptides classes, with antimicrobial activity. Liquid chromatography-mass spectrometry putatively identified secondary metabolites mainly composed of metabolites from the terpenoids and oligopeptide classes. Furthermore, molecular docking analysis revealed that the identified secondary metabolites exhibited a strong binding affinity towards B. cinerea pathogenicity factors, including aspartic protease, cutinase, lipase, and pectin methyltransferase. The strongest binding affinity (-6.644 kcal/mol) was observed towards aspartic protease, which was greater than the highest binding affinity (-4.783 kcal/mol) with a commercially used synthetic fungicide, captan. The annotated metabolites had a low predicted acute toxicity. Therefore, secondary metabolites from Bacillus MHSD_36 are composed of compounds with potential fungicidal activity against B. cinerea.