Metabolomic Characteristics of Lactic Acid Bacteria-fermented Yam and Its Regulatory Effects on Gut Microbiota

Yam (Dioscorea opposita), a traditional medicinal and edible plant, is rich in bioactive compounds such as polysaccharides and phenolics, and exhibits various biological activities, including immune modulation and antioxidant properties. To investigate the effects of lactic acid fermentation on the active components of Chinese yam and the regulatory effects of its fermentation products on the gut microbiota, Tiegun yam was fermented using Lactobacillus delbrueckii subsp. bulgaricus CICC 6045 and Streptococcus thermophilus CICC 20380. Non-targeted metabolomics combined with in vitro intestinal microbial culture was employed to systematically investigate the changes in metabolites after fermentation and the regulatory effects of the fermentation products on the intestinal microbiota. Lactic acid bacteria fermentation significantly resulted in 90 up- and 236 down-regulated metabolites, which were mainly enriched in some pathways such as phenylalanine and fructose/mannose metabolism. Moreover, the fermented products significantly promoted the growth of beneficial intestinal bacteria such as Lactobacillus and Bifidobacterium, and inhibited potential pathogens including Enterobacteriaceae and Clostridium. The study results highlighted the potential effects of yam and its fermentation products in beneficially modulating intestinal microbiota, and provided a scientific reference for development of deep processing functional products of yam.