Intestinal microbial composition changes induced by Lactobacillus plantarum GBL 16, 17 fermented feed and intestinal immune homeostasis regulation in pigs

In this study, Rubus coreanus (R. coreanus) byproducts with high polyphenol content were fermented with R. coreanus-derived lactic acid bacteria (Lactobacillus plantarum GBL 16 and 17). Then the effect of R. coreanus-derived lactic acid bacteria fermented feed (RC-LAB fermented feed) with probiotics (Bacillus subtills, Aspergillus oryzae, Yeast) as a feed additive for pigs on the composition of intestinal microbes and the regulation of intestinal immune homeostasis was investigated. Seventy-two finishing Berkshire pigs were randomly allotted to four different treatment groups and 18 replicates. RC-LAB fermented feed with probiotics increased the genera Lactobacillus, Streptococcus, Mitsuokella, Prevotella, Bacteroides spp., Roseburia spp., and Faecalibacterium prausnitzii, which are beneficial bacteria of the digestive tract of pigs. Also, RC-LAB fermented feed with probiotics decreased the genera Clostridium, Terrisporobacter, Romboutsia, Kandleria, Megasphaera and Escherichia, which are harmful bacteria. In particular, the relative abundance of the genera Lactobacillus and Streptococcus increased by an average of 8.51% and 4.68% in the treatment groups and the classes Clostridia and genera Escherichia decreased by an average of 27.05% and 2.85% in the treatment groups. In mesenteric lymph nodes (MLN) and spleens, the mRNA expression of transcription factors and cytokines in Th1 and Treg cells increased and the mRNA expression of Th2 and Th17 transcription factors and cytokines decreased, indicating a regulatory effect on intestinal immune homeostasis. RC-LAB fermented feed regulates gut immune homeostasis by influencing the composition of beneficial and detrimental microorganisms in the gut and regulating the balance of Th1/Th2 and Th17/Treg cells.