Molecular characterization of an endophytic strain of Bacillus subtilis with plant growth-promoting properties from a wild relative of papaya.

This article focuses on the genomic, proteomic, and functional characterization of Bacillus subtilis strain EVCu15, an endophytic bacterium isolated from the seeds of mountain papaya (Vasconcellea cundinamarcensis), highlighting its biocontrol and plant growth-promoting (PGP) potential. Whole genome sequencing revealed over 98% similarity with known B. subtilis strains and identified 15 secondary metabolite gene clusters involved in producing bioactive compounds such as surfactin, fengycin, plipastatin, bacillibactin, subtilomycin, subtilosin A, and bacilysin, alongside genes related to nutrient metabolism and hormone biosynthesis. Proteomic and liquid chromatography-mass spectrometry analyses confirmed the production and extracellular secretion of antimicrobial proteins, plant hormones (including salicylic acid, indole-3-acetic acid, and zeatin), and vitamins (notably vitamins D1, D2, E, K2, and pyridoxine). In vitro and greenhouse assays demonstrated that B. subtilis EVCu15 effectively antagonizes various fungal pathogens and inhibits the root-knot nematode Meloidogyne incognita, outperforming Bacillus amyloliquefaciens in nematicidal activity. The study underscores the strain's multifaceted role in sustainable agriculture, though it notes the need for further field evaluations.