Characterization of the Probiotic Properties and Cholesterol Metabolism Regulation Potential of Lactiplantibacillus plantarum QL-19.

Lactic acid bacteria (LAB) play a crucial role in food fermentation and human health. This study introduces Lactiplantibacillus plantarum (L. plantarum) QL-19, a novel probiotic strain isolated from traditional Hunan pickles and characterized via whole-genome sequencing and in vitro functional assays. The 3,396,702 genome contains 3236 predicted coding sequences, including genes associated with stress tolerance, adhesion, and cholesterol metabolism (cbh, cfa, and hydroxymethylglutaryl-CoA synthase). Genomic analysis further revealed biosynthetic gene clusters encoding antimicrobial and antioxidant compounds, emphasizing its functional versatility. A comprehensive safety assessment confirmed that QL-19 is non-pathogenic and non-hemolytic, meeting probiotic safety standards. In HepG2 cell-based experiments, L. plantarum QL-19 reduced intracellular total cholesterol levels. RT-qPCR and Western blotting were employed to evaluate the expression of genes and proteins involved in cholesterol metabolism. The results demonstrated that QL-19 enhanced cholesterol metabolism by upregulating the expression of SREBP2, LDLR, and CYP7A1, while downregulating NPC1L1 and HMGCR. The results suggest that QL-19 facilitates cholesterol metabolism through multiple pathways. Taken together with its 75.4% in vitro cholesterol degradation rate, these findings highlight the potential of QL-19 as a cholesterol-lowering probiotic candidate for cardiovascular health applications.