Abstract: This study aimed to select Lactobacillus with high bile salt hydrolase (BSH) and to explore its protective role against neonatal jaundice. The LBS selective medium supplemented with 25 U/mL nystatin was used to screen and identify Lactobacillus strains isolated from the feces of healthy newborns and breast milk. L. rhamnosus (LGG) was used as a positive control to evaluate the in vitro probiotic properties and bile salt hydrolase activity of the Lactobacillus strains. Thereafter, the protective effect and mechanism of the selected isolates with high bile salt hydrolase activity against phenylhydrazine hydrochloride (PHZ)-induced neonatal jaundice in rats were investigated by analyzing serum bilirubin levels, hepatotoxicity, and the expression of inflammatory cytokines and nuclear transcription factors in the liver. The results showed that compared with the LGG, L. gasseri FWJL-5, which was isolated from infant feces, exhibited outstanding in vitro probiotic properties and higher bile salt hydrolase activity than LGG. L. gasseri FWJL-5 significantly alleviated the increase in serum bilirubin levels, liver tissue swelling and hemolysis in PHZ-treated neonatal rats, reduced the release of hepatic enzymes, inhibited the secretion of proinflammatory cytokines, and promoted the expression of UGT1A1, pregnane X receptor (PXR), and farnesol X receptor (FXR). Taken together, L. gasseri FWJL-5 could regulate bilirubin metabolism in the liver by up-regulating the expression of FXR/PXR and UGT1A1, thereby alleviating neonatal jaundice in rats. Our findings may provide new ideas for the prevention and treatment of neonatal jaundice by L. gasseri.

Key words: Lactobacillus gasseri; bile salt hydrolase; neonatal jaundice; bilirubin metabolism