屎肠球菌对斑节对虾肠道代谢组学及炎性因子的影响

Effect of Enterococcus faecium on intestinal metabolomics and inflammatory factors of Penaeus monodon

摘要:

【背景】屎肠球菌(Enterococcus faecium)作为乳酸菌属的潜在益生菌，因其具有良好的生物学特性在动物养殖中应用广泛，但是屎肠球菌对肠道代谢组学的研究很少。【目的】以斑节对虾为试验动物，初步探究屎肠球菌R8对肠道代谢组学及炎性因子的影响，为屎肠球菌作为益生菌在对虾养殖中的应用提供理论基础。【方法】将400条斑节对虾随机分配，设计饲料中屎肠球菌添加量分别为10⁷、10⁸、10⁹ CFU/g的3个试验组，不添加屎肠球菌为对照组进行试验，养殖周期为28 d。养殖周期结束后测定斑节对虾免疫球蛋白M (immunoglobulin M, IgM)、对虾酚氧化酶(phenoloxidase, PO)、白介素6 (interleukin 6, IL-6)、补体片段3a (complement fragment 3a, C3a)的活性含量并运用LC-MS代谢组学研究肠道内源代谢物的变化，分析差异代谢物和相关的代谢通路。【结果】添加屎肠球菌对斑节对虾炎性因子有积极的影响，增加了斑节对虾体内免疫球蛋白IgM、对虾酚氧化酶、补体片段3a的含量，降低了其体内IL-6的含量，对肠道差异代谢物的分析发现，对照组与试验组共同差异代谢物165个，化合物成分主要是脂质和类脂分子、有机酸和衍生物、有机氧化合物、有机杂环化合物、核苷、核苷酸和类似物等。差异代谢物对37条代谢通路有影响，其中，花生四烯酸代谢通路、α-亚麻酸代谢通路、胆碱代谢通路和嘧啶代谢通路是显著富集的代谢通路(P<0.05)，而且花生四烯酸代谢、α-亚麻酸代谢、胆碱代谢、嘧啶代谢和甘油磷脂代谢的富集代谢物数目最多。【结论】屎肠球菌对斑节对虾肠道中的脂代谢、氨基酸代谢、核苷酸代谢及炎性因子有积极的影响，为屎肠球菌在对虾养殖中的应用奠定理论基础，具有重要的意义和应用前景。

Abstract:

[Background] As a lactic acid-producing probiotic candidate, Enterococcus faecium is widely used in animal breeding owing to the satisfactory biological characteristics. However, a few studies of the influence of E. faecium on intestinal metabonomics are available. [Objective] To explore the effect of E. faecium on intestinal metabonomics and inflammatory factors of Penaeus monodon (giant tiger prawn) and thus to lay a theoretical basis for the application of E. faecium as a probiotic in prawn culture. [Methods] A total of 400 giant tiger prawns were randomly classified into four groups. For three groups (experimental groups) of them, E. faecium was added into the feed at 10⁷, 10⁸, and 10⁹ CFU/g, respectively. For the remainder, no E. faecium was added to the feed, and this group was regarded as control. The experiment lasted 28 days. Then, the content of immunoglobulin IgM, phenol oxidase (PO), interleukin-6 (IL-6), and complement fragment 3a (C3a) in P. monodon was measured, and the changes of intestinal metabolites were studied by LC-MS. On this basis, differential metabolites and related metabolic pathways were analyzed.[Results] The addition of E. faecium had positive effect on the inflammatory factors of P. monodon. It increased the content of IgM, PO, and C3a and reduced the content of IL-6 in P. monodon. A total of 165 differential metabolites between the control group and the experimental groups were identified, which were mainly lipids and lipid-like molecules, organic acids and derivatives, organic oxygen compounds, organic heterocyclic compounds, nucleosides, nucleotides and analogues, etc. The differential metabolites were involved in 37 metabolic pathways, including arachidonic acid metabolism, α-linolenic acid metabolism, choline metabolism, and pyrimidine metabolism (P<0.05), and arachidonic acid metabolism α-linolenic acid metabolism, choline metabolism, pyrimidine metabolism, and glycerophosphatide metabolism topped the pathways in the number of metabolites.[Conclusion] E. faecium has positive effect on lipid metabolism, amino acid metabolism, nucleotide metabolism, and inflammatory factors in the intestine of P. monodon, which lays a theoretical foundation for the application of E. faecium in shrimp culture, and has important significance and application prospects.