Genomic Characterization and Functional Assessment of Cellulolytic and Antimicrobial Activities of Bacillus velezensis Strain hwrm2 Isolated from the Rumen of Hanwoo

This study characterized the cellulase and antimicrobial activities of Bacillus velezensis strain hwrm2 isolated from the rumen of Hanwoo cattle and analyzed its complete genome sequence to understand its genetic potential and phylogeny. This strain exhibited cellulolytic and xylanolytic activities, producing a maximum cellulase activity of 32.5 U/ml at 24 h. The strain showed antifungal activity against Aspergillus ochraceus and A. flavus and antibacterial activity against Salmonella enterica. Whole-genome sequencing revealed a single circular chromosome of 4.04 Mb (G+C content, 46.4%) containing 3,806 coding sequences. Phylogenomic analysis confirmed the taxonomic identity of hwrm2 as B. velezensis (ANI = 98.5%, dDDH = 89.3%). Functional annotation identified genes encoding cellulase, endo-1,4-β-xylanase, and β-glucosidase involved in cellulose and hemicellulose degradation as well as biosynthetic gene clusters associated with antimicrobial metabolite production, including surfactin, bacillaene, bacilysin, and bacillibactin. The coexistence of carbohydrate-active enzyme genes and antimicrobial biosynthetic pathways underscores the functional potential of this strain for fiber degradation and pathogen inhibition. These findings expand our understanding of aerobic rumen-derived bacteria and suggest that B. velezensis hwrm2 is a promising candidate for further evaluation as a functional microbial resource for fiber degradation and pathogen inhibition in ruminant feed and silage applications.