Genomic Insights and Phenotypic Assessment of Lactobacillus rhamnosus GYX-9: Unraveling Its Probiotic Potential in Ameliorating Obesity-Associated Metabolic Disorders

To prevent or improve obesity and metabolic diseases caused by long-term high-fat diets (HFD), this study screened probiotic strains based on their probiotic properties predicted from their whole genomes and validated their probiotic functions through in vitro and in vivo experiments. In the preliminary phase, Lactobacillus rhamnosus GYX-9, a strain with strong adhesion properties, was isolated from the gut of healthy infants. Functional annotation revealed high gene abundance related to processes such as the tricarboxylic acid cycle and lipid metabolism. Notably, genes encoding aldehyde dehydrogenase/alcohol dehydrogenase and acetyl-CoA acetyltransferase played significant roles in lipid reduction. Furthermore, this strain possesses genes involved in the acetate synthesis pathway, such as ackA and pta. In vitro validation demonstrated its strong ability to inhibit α-amylase and lower cholesterol. Intervention with this strain in high-fat mice reduced weight gain; increased high-density lipoprotein cholesterol (HDL-C) levels by 155.02%; enhanced catalase (CAT) antioxidant enzyme activity in the liver by 35.5%; and decreased colonic interleukin-1β (IL-1β) by 52.65%; and increased interleukin-10 (IL-10) levels to (170.55 ± 36.34) pg/mL.. The relative abundance of Bifidobacterium and Romboutsia increased, while Ileibacterium and Desulfovibrio decreased. These findings provide important theoretical and practical references for developing safe and effective obesity intervention strategies.