<i>Bifidobacterium animalis</i> subsp. <i>lactis</i> LKM512 Alleviates Inflammatory Bowel Disease in Larval Zebrafish by Reshaping Microbiota

Inflammatory bowel disease (IBD) is a worldwide issue, and the increased incidence has brought a heavy burden to patients and society. Gut microbiota is involved in the pathogenesis of IBD, and targeting the microbiota, such as probiotics, has emerged as a potential therapy for the treatment of IBD. Here, the effect of Bifidobacterium animalis ssp. lactis LKM512 (LKM512), an anti-aging probiotic, on dextran sulfate sodium salt (DSS)-induced IBD in larval zebrafish was determined. Supplementation of LKM512 promoted the survival rate of the larvae, together with increased locomotor activities and body length. In addition, LKM512 treatment enhanced mucus secretion and alleviated intestinal injury, and these results were associated with the upregulation of mucin-related and downregulation of inflammatory markers. Moreover, LKM512 increased the diversity of the microbiota and ameliorated the dysbiosis by increasing the abundance of Bacteroidetes and Firmicutes and reducing the abundance of Proteobacteria. Specifically, the abundance of beneficial bacteria, including the short-chain fatty-acids (SCFAs)-producing genera Lachnospiraceae_NK4A136_group, Muribaculaceae, and Alloprevotella, was increased by LKM512, while the abundance of harmful genera, such as Pseudomonas, Halomonas, and Escherichia-Shigella, was reduced by LKM512. Consistent with these findings, the microbial functions related to metabolism were partly reversed by LKM512, and importantly, fermentation of short-chain fatty acids-related functions were enhanced by LKM512. Therefore, LKM512 might be one potential probiotic for the prevention and treatment of IBD, and further studies that clarify the mechanism of LKM512 would promote the application of LKM512.