Isolation, Characterization, and Whole-Genome Analysis of a Porcine Bacillus velezensis Strain with Potential Applications in Animal Husbandry

The development and identification of environmentally friendly, safe and effective alternatives to antibiotics have emerged as a shared global focus. To provide a foundation for developing an effective antibiotic alternatives of livestock and poultry, healthy pig feces were used to isolated probiotic Bacillus strain, which was identified by colony morphology, bacillus -specific PCR and 16S rRNA sequencing. Then its biochemical characterization, stress tolerance, enzyme production, antimicrobial activity, safety in mice and whole-genome sequence were analyzed. The results showed that a Bacillus velezensis strain, designated BVLY028, was isolated and identified. It exhibited excellent environmental adaptability and stress resistance, which grew well at pH 6–8, tolerated a pH range of 2–10, resisted high temperatures of 60–80 ℃ and 0.3% bile salts, and maintained high survival rates after treatment in simulated gastrointestinal fluids. Meanwhile, BVLY028 strain was capable of secreting protease, cellulase, amylase, lipase and exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli , with inhibition rates of 62.50% (5/8) and 33.33% (12/36), respectively. Oral administration tests in mice indicated a good safety profile. Whole-genome analysis revealed a genome size of 3,929,791 bp, with a GC content of 46.5%, predicting 62 carbohydrate-active enzyme genes and multiple secondary metabolite gene clusters, including those encoding difficidin, macrolactin H, fengycin, bacillaene, bacillibactin, and bacilysin, which genetically support its enzyme-producing and antibacterial potential. The results demonstrate that BVLY028 possesses excellent tolerance, enzyme production capacity, antibacterial activity, and safety, indicating its potential value as a candidate probiotic strain for livestock and poultry.