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Gut microbiota and its metabolites play a key role in host metabolism. Our previous study found supplemental Lactobacillus delbrueckii affected lipid metabolism of pigs, however, the underlying mechanism is unclear. In this study, we investigated the effects of L. delbrueckii on colonic bacteria composition and its metabolites, serum lipids and hormone levels, fat metabolism related enzyme activity and gene expression in various tissues of growing-finishing pigs. Twelve pigs were randomly distributed into two groups (n = 6), and pigs in each group were fed diets with (Con + LD) or without (Con) 0.1 % L. delbrueckii for 28 days. Results exhibited the deceased triglyceride (TG) levels and elevated free fatty acid (FFA) contents in serum and increased concentrations of butyric acid in colonic digesta after L. delbrueckii supplementation. Dietary L. delbrueckii increased abundance of Lactobacillus and Butyrivibri and tended to increase abundance of Akkermansia and Megasphaera in colonic digesta. L. delbrueckii consumption up-regulated glucagon-like peptide1 (GLP-1), monocarboxylate transporter1 (MTC1) and sodium-dependent monocarboxylate transporter1 (SMCT1) expression in colonic tissue. Administration of L. delbrueckii tended to increase lipoprotein lipase (LPL) activity, up-regulated CPT-1, angiopoietin-like protein 4 (Angpt14), LPL and triglyceride hydrolase (TGH) expression and down-regulated fatty acid synthetase (FAS), G protein-coupled receptor 41(GPR41) and GPR43 expression in the liver. L. delbrueckii addition increased adenosine monophosphate activated protein kinase (AMPK) expression in longissimus dorsi, upregulated LPL, CPT-1, Angptl4 and cluster of differentiation 36 (CD36) expression in subcutaneous fat, and enhanced LPL, CPT-1, TGH, adipocyte determination and differentiation-dependent factor 1 (ADD1) and hormone sensitive lipase (HSL) expression in leaf lard. These findings suggested that L. delbrueckii might enhance lipolysis and fatty acid β-oxidation to lower serum TG levels via colonic microbiota modulation and short chain fatty acids-mediated lipid metabolism of growing-finishing pigs.

Microbiota-targeted therapies for hypercholesterolemia get more and more attention and are recognized as an effective strategy for preventing and treating cardiovascular disease. The experiment was conducted to investigate the cholesterol-lowering mechanism of Lactobacillus delbrueckii in a pig model. Twelve barrows (38.70 ± 5.33 kg) were randomly allocated to two groups and fed corn–soybean meal diets with either 0% (Con) or 0.1% Lactobacillus delbrueckii (Con + LD) for 28 days. L. delbrueckii–fed pigs had lower serum contents of total cholesterol (TC), total bile acids (TBAs), and triglyceride, but higher fecal TC and TBA excretion. L. delbrueckii treatment increased ileal Lactobacillus abundance and bile acid (BA) deconjugation and affected serum and hepatic BA composition. Dietary L. delbrueckii downregulated the gene expression of ileal apical sodium-dependent bile acid transporter (ASBT) and ileal bile acid binding protein (IBABP), and hepatic farnesoid X receptor (FXR), fibroblast growth factor (FGF19), and small heterodimer partner (SHP), but upregulated hepatic high-density lipoprotein receptor (HDLR), low-density lipoprotein receptor (LDLR), sterol regulatory element binding protein-2 (SREBP-2), and cholesterol-7α hydroxylase (CYP7A1) expression. Our results provided in vivo evidence that L. delbrueckii promote ileal BA deconjugation with subsequent fecal TC and TBA extraction by modifying ileal microbiota composition and induce hepatic BA neosynthesis via regulating gut–liver FXR–FGF19 axis.