Preparation of Lactobacillus paracei TK1501 postbiotic and its inhibitory effect against Helicobacter pylori infection in mice

Abstract

To prepare a postbiotic using soybean fermentation product of Lactobacillus paracasei TK1501 and evaluate its inhibitory effect against Helicobacter pylori (Hp) infection in mice. L. paracasei TK1501 was cultured for 32 h at 37 ℃ in an anaerobic condition for solid substrate fermentation with a solid to water ratio of 1:1.5 in the substrate and an inoculation density of 5×107 CFU/mL. The postbiotic was isolated and purified using macroporous resin XAD-16N adsorption, cation exchange chromatography and HPLC, and its stability and antibacterial activity were assessed. The inhibitory effect of this postbiotic against Hp infection was evaluated in a mouse model with gastric mucosal Hp infection, which were treated with the postbiotic via gavage for 4 weeks at the dose of 0.02 or 0.1 mL. Serum levels of TNF-α and IL-1β of the mice were analyzed after the treatments, and gastric tissues of the mice were collected for HE staining. L. paracasei TK1501 postbiotic could be easily degraded by protease and had good thermal stability and tolerance to exposures to acid, base, and organic solvents. In the in vitro experiment, the postbiotic showed strong inhibitory effects in bacterial cultures of Staphylococcus aureus, Hp and other common pathogenic bacteria without obviously affecting the resident bacteria in the digestive tract. In the mouse models, treatment with the postbiotic at the dose of 0.1 mL significantly alleviated Hp infection and lowered the serum levels of TNF-α and IL-1β of the mice. L. paracasei TK1501 postbiotic has strong inhibitory effects on Hp and Staphylococcus aureus but not on normal intestinal flora in mice.