Functional Bacillus licheniformis-based probiotic beverage modulates gut microbiota and host transcriptome to counteract obesity in a high-fat diet mouse model

Obesity is characterized by gut microbiota dysbiosis, systemic inflammation, and multi-organ dysfunction. This study evaluated a Bacillus licheniformis-based probiotic beverage in high-fat diet (HFD)-induced obese mice. Male C57BL/6 mice received standard diet or HFD, with or without probiotic supplementation, for 21 weeks. Probiotic-treated HFD mice exhibited significantly reduced weight gain, visceral fat, hepatic steatosis, renal injury, and splenic hematopoietic stress. Glucose tolerance improved, and serum cholesterol decreased. Gut microbiota analysis revealed increased α-diversity, partial restoration of the Firmicutes/Bacteroidetes ratio, and enrichment of short-chain fatty acid-producing taxa. Liver transcriptomics showed downregulation of interferon and antigen presentation pathways, and upregulation of genes involved in tissue regeneration and lipid metabolism. These integrated physiological, microbial, and transcriptomic changes suggest systemic protection by Bacillus licheniformis probiotic beverage against HFD-induced damage. Our findings support its potential as a non-dairy functional intervention to modulate the gut–organ axis and restore metabolic balance in obesogenic diets.