Genome Sequencing and Characterization of Bacillus velezensis N23 as Biocontrol Agent against Plant Pathogens.

The overuse of chemical fungicides against fungal pathogens adversely affects soil and plant health, resulting in environmental problems and food safety. Therefore, biocontrol is considered as an environmentally friendly and cost-effective green technique in environmental protection and agricultural production. We obtained a bacterial strain N23 from a contaminated plate which showed significant inhibition to anthracnose. The strain N23 was identified as Bacillus velezensis based on 16S rRNA gene, gyrA gene, and whole-genome sequence. The bacterium N23 was able to suppress the mycelial growth of numerous plant pathogenic fungi on solid media. Tomato seeds treated with strain N23 showed significantly higher germination levels than untreated ones. Moreover, strain N23 effectively reduced the lesion area of pepper anthracnose disease in planta. The gene clusters responsible for antifungal metabolites (fengycin, surfactin, and iturin) were identified in the genome sequence of N23 based on genome mining and PCR. Furthermore, methanol extracts of the bacterial culture caused significant inhibition in growth of the fungal Colletotrichum sp. and Botrytis cinerea. These findings suggested that B. velezensis N23 could be a potential biocontrol agent in agricultural production and a source of antimicrobial compounds for further exploitation.