Comparative analysis of barley dietary fiber fermented with and without <i>Lactiplantibacillus plantarum</i> dy-1 in promoting gut health and regulating hepatic energy metabolism in high-fat diet-induced obese mice

A previous study has revealed that <i>Lactiplantibacillus plantarum</i> (<i>Lp. plantarum</i>) dy-1 fermentation changed the structural properties and <i>in vitro</i> fecal fermentation characteristics of barley dietary fiber. However, the health-promoting effects of fermented dietary fiber <i>in vivo</i> remained unclear. This study was aimed at comparing the ameliorative effects of barley dietary fiber fermented with or without <i>Lp. plantarum</i> dy-1 on lipid metabolism, gut microbiota composition and hepatic energy metabolism. After a twelve-week intervention, fermented barley dietary fiber (FBDF) reduced the body weight and fat accumulation in liver and epididymal white adipose tissue, improved HFD-induced hyperlipidemia and glucose intolerance, and increased short chain fatty acid (SCFA) levels, exhibiting effects that were better than those of raw barley dietary fiber (RBDF). FBDF supplementation improved the gut microbiota composition, specifically enhancing the abundance of probiotic and SCFA-producing bacteria, such as <i>Akkermansia</i> and <i>Muribaculaceae</i>, while RBDF exhibited regulatory effects on harmful bacteria (<i>Escherichia</i>-<i>Shigella</i> and <i>Desulfovibrionaceae</i>). Additionally, FBDF up-regulated the expression of genes related to energy metabolic processes, such as aerobic respiration and oxidative phosphorylation, inhibited the genes related to lipid biosynthetic metabolism, and improved the activities of hepatic energy metabolism-related enzymes, demonstrating effects that were better than those of RBDF. Therefore, this study indicated the potential of using FBDFs as healthy food resources to prevent obesity or as prebiotics to improve gut microbiota.