Huyben David, Roehe Beeke K, Bekaert Michaël, Ruyter Bente, Glencross Brett
Institute of Aquaculture, University of Stirling, Stirling, United Kingdom.
Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada.
Front Microbiol. 2020 Dec 23;11:589898. doi: 10.3389/fmicb.2020.589898. eCollection 2020.
Researchers have adjusted dietary lipid:protein ratios and n-3 long-chain polyunsaturated fatty acids (LC-PUFA) to optimize the growth performance of Atlantic salmon. However, dietary impacts on the gut microbiome are lacking, especially under varying environmental conditions. To examine this response, post-smolt salmon (184 ± 5 g) were fed diets with lipid:protein ratios considered low (180, 570 g/kg) and high (230, 460 g/kg) along with low and high levels of n-3 LC-PUFA (7 or 14 g/kg) while fish were reared under low and high levels of dissolved oxygen (6.7 or 8.0 mg/L). At day 0, 35 and 116, digesta in the distal intestine were collected and analyzed for viable counts and 16S ribosomal RNA (rRNA) genes (V4 region) using Illumina MiSeq. The reduction in oxygen had negligible effects, except on viable plate counts of total bacteria and an initial effect on beta-diversity. In contrast, the high lipid (HL) diets had an increased alpha-diversity (e.g., Shannon and Chao-1) at day 0 and day 35 whereas high n-3 diets suppressed these indices at day 116. Generally, a reduction in alpha-diversity was observed over time and an interaction between lipid:protein ratio x n-3 was found. Between diets, beta-diversity and phyla abundance were similar as both Proteobacteria (44%) and Firmicutes (21%) dominated. However, at the genus level , , Weissella, and , were associated with low lipid (LL) diets while the high lipid diets were associated with less abundant bacteria, e.g., . At day 116, the relative abundance of the Tenericutes phylum increased 10-fold (36%). Fish fed the high lipid diet with high n-3 had reduced alpha-diversity, lowest abundance of lactic acid bacteria, and highest abundance of , which may indicate a less healthy gut microbiome. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis revealed that saturated and unsaturated fatty acid biosynthesis pathways were several folds higher in fish fed the high lipid diet, possibly to compensate for the lack of dietary n-3. In summary, our results show that the viable plate counts, alpha-diversity, beta-diversity, and predictive function of gut bacteria in Atlantic salmon post-smolts are influenced by dietary lipid:protein ratio and n-3 LC-PUFA over several time points with little effect by dissolved oxygen.
研究人员已调整饮食中的脂质与蛋白质比例以及n-3长链多不饱和脂肪酸（LC-PUFA），以优化大西洋鲑鱼的生长性能。然而，饮食对肠道微生物群的影响尚不清楚，尤其是在不同环境条件下。为了研究这种反应，将后幼鲑（184±5克）投喂脂质与蛋白质比例分别为低（180、570克/千克）和高（230、460克/千克）以及n-3 LC-PUFA含量低和高（7或14克/千克）的饲料，同时将鱼饲养在低和高溶解氧水平（6.7或8.0毫克/升）的环境中。在第0、35和116天，收集远端肠道中的消化物，使用Illumina MiSeq分析其活菌计数和16S核糖体RNA（rRNA）基因（V4区域）。氧气减少的影响可忽略不计，除了对总细菌的活菌平板计数有影响以及对β-多样性有初始影响。相比之下，高脂（HL）日粮在第0天和第35天增加了α-多样性（例如香农指数和Chao-1指数），而高n-3日粮在第116天抑制了这些指数。一般来说，随着时间的推移观察到α-多样性降低，并且发现脂质与蛋白质比例×n-3之间存在相互作用。在不同日粮之间，β-多样性和门的丰度相似，因为变形菌门（44%）和厚壁菌门（21%）占主导地位。然而，在属水平上，魏斯氏菌属等与低脂（LL）日粮相关，而高脂日粮与丰度较低的细菌相关，例如。在第116天，柔膜菌门的相对丰度增加了10倍（36%）。投喂高脂质高n-3日粮的鱼α-多样性降低，乳酸菌丰度最低，而某菌丰度最高，这可能表明肠道微生物群不太健康。通过未观察状态重建进行群落系统发育研究（PICRUSt）分析表明，投喂高脂日粮的鱼中饱和和不饱和脂肪酸生物合成途径高出几倍，可能是为了补偿日粮中n-3的缺乏。总之，我们的结果表明，大西洋鲑后幼鱼肠道细菌的活菌平板计数、α-多样性、β-多样性和预测功能在几个时间点上受到饮食中脂质与蛋白质比例和n-3 LC-PUFA的影响，而溶解氧的影响很小。
