Effects of Lactobacillus paracasei K71 on gut microbiota composition and lipid metabolism in ob/ob mice.

We investigated the effects of heat-killed Lactobacillus paracasei K71 (K71）on lipid metabolism and gut microbiota in an ob/ob mouse model of obesity. Wild-type and ob/ob (ob-AIN group) mice were fed an AIN-93G diet or an AIN-93G diet containing K71 (ob-K71 group) for 90 d. Serum lipids, hepatic gene expression, and gut microbial populations were evaluated. K71 intake had no significant effect on body weight or lipid metabolism in the liver, while serum non-esterified fatty acids (NEFA) were lower in the ob-K71 group than in the ob-AIN group. In addition, the expression of serine palmitoyl transferase (SPT)-1, a key enzyme in the formation of ceramides associated with insulin resistance, was also lower in the livers of the ob-K71 group than in those of the ob-AIN group. Sequencing of the 16S ribosomal RNA gene revealed that K71 intake suppressed the changes in gut microbiota related to type 2 diabetes and nonalcoholic steatohepatitis. Our results suggest that K71 ingestion alters gut microbiota composition and improves insulin resistance via the ceramide