The objective of this study was to evaluate the anti-inflammatory effect of Latilactobacillus sakei SMFM2017-NK1 (LS1), L. sakei SMFM2017-NK3 (LS2), and Limosilactobacillus fermentum SMFM2017-NK2 (LF) on colitis using an animal model. DSS (dextran sulfate sodium salt) was orally injected into C57BL/6N mice to induce inflammation in the colon for seven days. Colitis mice models were treated with LS1, LS2, and LF, respectively, and Lacticaseibacillus rhamnosus GG (LGG) was used as a positive control. During oral administration of lactic acid bacteria, the weights of the mice were measured, and the disease activity index (DAI) score was determined by judging the degree of diarrhea and bloody stool. When comparing the differences between the minimum weight after DSS administration and the maximum weight after lactic acid bacteriaadministration were compared, the LF-treated group showed the highest weight gain at 8.91%. The DAI scores of the LF, LS2, and LGG groups were lower than that of the control group. After sacrifice, mRNA expression levels for proinflammatory cytokines (TNF-α, IL-1β, IL-6, and IFN-γ) and mediators (iNOS and COX-2) in the colon were measured. LF was selected as a superior strain for anti-inflammation in the colon. It was further analyzed to determine its biochemical characteristics, cytotoxicity, and thermal stability. Catalase and oxidase activities for LF were negative. In cytotoxicity and heat stability tests, the LF group had higher cell viability than the LGG group. The genome of LF was obtained, and 5682 CDS, 114 tRNA, 2 RNA, and 5 repeat regions were predicted. Especially, LF could be distinguished from the other three L. fermentum strains based on taxonomic profiling, specific orthologous genes of the strain, and genomic variants. The results of this study suggest that L. fermentum SMFM2017-NK2 is a novel strain with an anti-inflammatory effect on colitis.
Keywords: IBD; anti-inflammatory effect; comparative genomics; lactic acid bacteria.