Fish intestine contains different types of microbiomes, and bacteria are the dominant microbiota in fishes. Studies have identified various core gut bacteria in fishes. However, little is known about the composition and their relative functions of gut microbial community along the intestine. To explore this, the current study investigated the microbial community distribution along the gut in Anguilla japonica. By 16S rRNA gene sequencing, we profiled the gut microbiota in eel along the three regions (anterior intestine (AI), the middle intestine (MI) and the posterior intestine (PI)). Results suggested that the three regions did not have significant differences on the observed species and diversities. The cluster tree analysis showed that the bacteria community in MI was closer to PI than the AI. The dominant bacteria in AI were the Proteobacteria, in which the majority was graduated replaced by Bacteroidetes along the gut to PI region. Through PICRUSt analysis, shifts in the bacterial community along the gut were found to affect the genetic information processing pathways. Higher levels of translation and transcriptional pathway activities were found in MI and PI than in AI. The dominant bacterial species were different among the regions and contributed to various biological functions along the gut.

中文翻译：

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日本鳗（Anguilla japonica）肠道肠道菌群的变化

鱼肠含有不同类型的微生物群，细菌是鱼类的主要微生物群。研究已经确定了鱼类中的各种核心肠道细菌。然而，人们对沿着肠道的肠道微生物群落的组成及其相对功能知之甚少。为了探索这一点，目前的研究调查了日本鳗鲡肠道中的微生物群落分布. 通过16S rRNA基因测序，我们沿着三个区域（前肠（AI）、中肠（MI）和后肠（PI））分析了鳗鱼的肠道微生物群。结果表明，三个地区在观察到的物种和多样性上没有显着差异。聚类树分析表明，MI 中的细菌群落比 AI 更接近 PI。AI中的优势细菌是变形杆菌，其中大部分被拟杆菌取代。沿着肠道到 PI 区域。通过 PICRUSt 分析，发现沿肠道细菌群落的变化会影响遗传信息处理途径。在 MI 和 PI 中发现比在 AI 中更高水平的翻译和转录通路活性。不同地区的优势细菌种类不同，并有助于肠道的各种生物学功能。