Abstract: In order to explore the influence of pasteurized fermented milk with probiotic Lactobacillus plantarum YW11 on the human intestinal flora structure, an in vitro simulated human digestion model was established and high-throughput 16S rRNA sequencing was applied to analyze the diversity and composition of the intestinal flora. Results indicated that the pasteurized fermented milk could increase the richness and diversity of intestinal microbial species. At the phylum level, it increased the abundance of Firmicutes and reduced the abundance of Proteobacteria. At the genus level, it increased the abundance of highly enriched bacteria and the abundance of 45.71% of the intestinal flora. In addition, the fermented milk increased the abundance of butyric acid-producing bacteria, such as Lachnospiraceae, Roseburia, Ruminococcus, and the abundance of Lactobacillus and Bifidobacterium. At the same time, the fermented milk also increased the bacteria implicated in relieving inflammatory bowel disease (IBD), such as Bacteroides, Faecalibacterium, Phascolarctobacterium and Collinsella, and reduced those related to the development of IBD, such as Erysipelotrichaceae, Pseudomonas and Escherichia-Shigella, indicating the beneficial effect of the pasteurized fermented milk on the human intestinal flora. Therefore, this fermented milk can function to regulate the human intestinal flora. These experimental results can provide a theoretical basis for the development of probiotic-fermented milk.

Key words: Lactobacillus plantarum YW11, pasteurized fermented milk, inflammatory bowel disease, intestinal flora