Abstract

Bacillus species are renowned for producing diverse secondary metabolites with antimicrobial and plant growth-promoting (PGP) activities. This study presents a genomic and functional characterization of Bacillus stercoris B.PNR2, isolated from nutrient-limited volcanic soil in Buriram Province, Northeastern Thailand. The strain exhibited antifungal activity against Fusarium oxysporum and Colletotrichum spp., along with PGP traits such as indole-3-acetic acid (IAA) production and phosphate solubilization. Whole-genome sequencing revealed a 4.11 Mb genome containing 4,283 coding sequences, 60 tRNA genes, and 5 rRNA operons, with a G+C content of 43.83%. Genome analysis identified 7 genes associated with IAA biosynthesis, 5 genes involved in phosphate solubilization (including alkaline phosphatase and phytase), 6 genes for siderophore biosynthesis and transport (bacillibactin cluster), and 9 genes related to nitrogen metabolism (nitrate/nitrite reductases, glutamine synthetase, ammonium transporters). AntiSMASH identified 13 biosynthetic gene clusters, including fengycin, bacillaene, surfactin, bacilysin, bacillibactin, and subtilosin A, with several showing low similarity to known clusters, suggesting potential for novel metabolite production. Phylogenomic analysis placed B.PNR2 within the B. stercoris clade. The genome also encoded 41 antimicrobial resistance genes and 322 transporter genes, indicating adaptive and defensive capabilities. The integration of genomic and functional traits supports B. stercoris B.PNR2 as a promising biofertilizer and biocontrol agent.

Key words: Bacillus stercoris, Biocontrol agent, Biosynthetic gene clusters (BGCs), Genome mining, Secondary metabolites