Table_1_An Overlooked Prebiotic: Beneficial Effect of Dietary Nucleotide Supplementation on Gut Microbiota and Metabolites in Senescence-Accelerated Mouse Prone-8 Mice.DOCX

Nucleotides (NTs) are regulatory factors in many biological processes and play important roles in the growth, development, and metabolism of living organisms. We used senescence-accelerated mouse prone-8 (SAMP8) to investigate the effects of NTs on the gut microbiota and metabolites. And the promoting effect of NTs on the growth of a probiotic (Lactobacillus casei) was explored through in vitro experiments. The results showed that the sequencing depth of 16S rDNA covered all microbial species in the feces of SAMP8. Supplementation with exogenous NTs to the diet enhanced the diversity of the gut microbiota, reduced the abundance of bacteria with negative effects on the body (such as Verrucomicrobia, Ruminococcaceae, Akkermansia and Helicobacter), and increased the abundance of the microbiota, which had beneficial effects on the mice (such as Lactobacillus, Candidatus saccharimonas and Lachnospiraceae_NK4A136_group). Metabonomic analysis showed that NT deficiency in the diet significantly affected metabolites in the mouse feces. The metabolites in mice supplemented with NTs tended to be normal (SAMR1). The differentially expressed metabolites caused by NT addition are involved in various pathways in the body, including linoleic acid metabolism, vitamin B6 metabolism, and histidine metabolism. Correlation analysis revealed a significant correlation between the gut microbiota and differentially expressed metabolites caused by the addition of NTs. In vitro experiments showed that NTs significantly promoted the growth, secretion of biofilm and extracellular polymeric substance of L. casei. NTs also promoted the ability of the crude extract of L. casei to resist the secretion of Shigella biofilm. Thus, NTs can regulate the abundance of the gut microbiota and alter the metabolic expression of the intestinal microbiome.

核苷酸（Nucleotides，NTs）是众多生物过程中的调控因子，在生物体的生长、发育与代谢过程中发挥关键作用。本研究采用快速老化易感小鼠8型（senescence-accelerated mouse prone-8, SAMP8）作为模型，探究核苷酸对肠道菌群及代谢物的影响，并通过体外实验验证核苷酸对益生菌干酪乳杆菌（Lactobacillus casei）生长的促进作用。测序结果显示，16S rDNA测序深度覆盖了SAMP8小鼠粪便中的所有微生物物种。日粮添加外源性核苷酸可提升小鼠肠道菌群的多样性，降低对机体有害的细菌丰度（如疣微菌门(Verrucomicrobia)、瘤胃球菌科(Ruminococcaceae)、艾克曼菌属(Akkermansia)以及螺杆菌属(Helicobacter)），同时增加对小鼠有益的菌群丰度（如乳杆菌属(Lactobacillus)、候选糖单胞菌属(Candidatus saccharimonas)以及Lachnospiraceae_NK4A136_group）。代谢组学分析表明，日粮中核苷酸缺乏会显著改变小鼠粪便中的代谢物谱；补充核苷酸的小鼠，其粪便代谢物谱趋近于正常老化小鼠SAMR1的水平。核苷酸添加所诱导的差异表达代谢物，参与机体多条代谢通路，包括亚油酸代谢、维生素B6代谢以及组氨酸代谢通路。相关性分析显示，肠道菌群与核苷酸添加诱导的差异表达代谢物之间存在显著关联。体外实验结果表明，核苷酸可显著促进干酪乳杆菌的生长、生物膜与胞外聚合物的分泌，同时提升干酪乳杆菌粗提物抑制志贺氏菌(Shigella)生物膜分泌的能力。综上，核苷酸可调控肠道菌群的丰度，并改变肠道微生物组的代谢表达谱。