鱼类肠道菌群与机体脂质代谢关系研究进展

鱼类肠道内存在着大量的微生物类群,其在宿主生长发育、代谢及免疫调控过程中扮演着重要的角色。大量研究显示肠道菌群与宿主脂代谢关系密切,能够通过调节肠道短链脂肪酸(short-chain fatty acids, SCFAs)、内毒素(lipopolysaccharide, LPS)、胆汁酸、氧化三甲胺等菌群代谢产物以及肠上皮细胞的通透性,影响宿主脂质代谢。本文对国内外鱼类肠道菌群及其与机体脂质代谢作用关系进行梳理,综合报道了鱼类肠道菌群的组成、脂类营养对鱼类肠道菌群的影响、鱼类肠道菌群与机体脂质代谢的关系及基于肠道菌群调控鱼类脂质代谢的策略。在鱼类肠道中,菌群种类及结构的变化或可作为鱼类脂代谢紊乱的早期诊断标志。在此基础上,基于肠道菌群稳态维持而采取调控手段,如合理应用益生菌、益生元等,或将为鱼类等水产动物脂质代谢紊乱防控提供新的方法。

Advances of intestinal microbiota and lipid metabolism of fish

In recent decades, the incidences of metabolic syndrome of cultured fish caused by unbalanced nutrition components or excessively large energy intake, have dramatically increased globally, and triggered gut inflammation, metabolic disorders, body stress, and decreased immunity defense. Related studies have mainly focused on target tissues of the body, such as the liver and adipose tissue. However, intestinal microbiota in fish, as another most important "tissue", is usually neglected. The gut microbiota plays an important role in the process of growth and development, immune defense, energy absorption, and metabolism of lipids or glucose. To deeply address the relationship among the feed, gut microbes, and lipid metabolism in fish, we firstly clarified the main composition and structure of the gut microbiota in marine and fresh water fish. Then, the effects of feed lipid nutrition on intestinal microbes were analyzed, including the lipid source type and level. Regarding the relationship between the gut microbes and the body lipid metabolism, the causality and effects of the gut microbes on the lipid metabolism were expounded. Specifically, possible mechanisms of host lipid metabolism disorder because of altered gut microbes were described, focusing on the production of short chain fatty acids (SCFAs), lipopolysaccharide (LPS), bile acids, trimethylamine oxide (TMAO), and the permeation of the gut epithelial cells. In particular, several strategies regarding lipid metabolism regulation based on the microbes were advanced, such as the application of new feed sources, prebiotics, and probiotics. Thus, we suggested that the structure and compositional change of the gut microbiota could be used as the symbol for the dysfunction of host lipid metabolism. Furthermore, taking steps based on the theory of the gut steady-state will provide feasible ways to improve the lipid metabolism dysfunction of fish, including clarifying the interactive mechanisms between the microbes and the host, and exploring indigenous probiotics depending on the culture dependent methods and micro-ecological agents.