Identification and comparative genomic analysis of two Bacillus subtilis producing antifungal lipopeptide.

Bacillus subtilis demonstrates functional diversity through production of structurally distinct lipopeptides, demonstrating significant potential for biocontrol applications. Two high-yield lipopeptide-producing strains, SL-2(7216.4 mg/L) and L6(3462.2 mg/L), were isolated from oil-contaminated soil. Their lipopeptide composition, antifungal activity, and genomic features related to secondary metabolite synthesis were systematically analyzed. Both strains predominantly produced surfactin and fengycin, with SL-2 showing higher proportions of long-chain components. Crude lipopeptide extracts from both strains strongly inhibited 5 typical plant pathogenic fungi (Botrytis cinerea, Alternaria tenuissima, Fusarium redolens, Pythium spinosum and Rhizoctonia solani), while SL-2 additionally suppressed 3 phytopathogenic fungi (Colletotrichum capsici, Fusarium solani and Mucor parvisporus). Genomic analysis revealed SL-2 (4.11 Mbp) and L6 (4.36 Mbp) harbor 14 and 11 secondary metabolite gene clusters, respectively. SL-2 exhibited enriched genetic pathways for quorum sensing, two-component systems, and ABC transporters. SL-2 contains a more complete biosynthetic Nis operon for lanthipeptide class I which is crucial for the production of mature antimicrobial peptides by Gram-positive bacteria and the production and transport of the antifungal substance subtilin. SL-2 also contains the unique gene blpAB related to ABC-type bacteriocin/lantibiotic exporters, which is involved in bacteriocin production and transport. Lipopeptide-producing bacterium Bacillus subtilis and its genomics research not only provide genomic data and research direction for further excavation of strain function and genetic engineering modification, but also provide broad-spectrum, high-yielding strain resources with industrial fermentation and commercial prospects for the development of bacterial agents in the field of agricultural biological control.