Whole-genome sequencing and probiotic properties of Lactobacillus helveticus KM7 isolated from the gut of the Chinese honey bee (Apis cerana): A promising exopolysaccharide-producing strain.

Lactobacillus helveticus is a probiotic bacterium widely used in the food industry. In this study, we evaluate the safety and probiotic properties of L. helveticus strain KM7, isolated from the gut of Apis cerana, through whole-genome sequencing and in vitro experiments. The complete genome consists of 2,164,024 bp, encoding 2192 genes with an average GC content of 36.82%. The strain lacks identifiable virulence factor genes and antibiotic resistance genes, shows no hemolytic activity, and cannot produce biogenic amines such as spermine, cadaverine, or putrescine. L. helveticus KM7 exhibited strong acid and bile salt tolerance, superior adhesion capacity, and remarkable antioxidant activity, with its genome harboring genes associated with these traits. It contains gene clusters potentially involved in the biosynthesis of bacteriocins Helveticin J and Enterolysin A, as well as encoding multiple genes of carbohydrate-active enzymes. Moreover, KM7 demonstrated excellent exopolysaccharide-producing capability, and glucose supplementation in the medium enhanced yield. These findings indicate that KM7 is a safe strain with promising probiotic properties, highlighting its potential for food applications.