Abstract Intestinal microbiota studies based on high-throughput sequencing have attracted increasing attention due to its vital impact on host health. However, the taxonomical profile in relative proportion does not reflect the quantity of the intestinal bacteria and the inter-sample differences among taxa. In this study, we applied a high-throughput absolute abundance quantification method that used an internal standard strain to simultaneously obtain both the relative and absolute abundances in the intestinal bacterial community of farmed Nile tilapia (Oreochromis niloticus). The results showed that the structure, relative and absolute abundances, and function of the intestinal indigenous microbiota didn’t change significantly after adding a low concentration of internal standard strain, and a comprehensive quantitative intestinal bacterial ecology was obtained. We first found that the total absolute abundance of the intestinal indigenous bacteria in farmed Nile tilapia was 2.95 × 108 cells g−1, and most genera concentrations were in the range of 103 to 105 cells g−1. The intestinal bacterial community was dominated by Cetobacterium with a concentration of 108 cells g−1, followed by Plesiomonas, Romboutsia, and Escherichia-Shigella with concentrations of over 107 cells g−1. The potential intestinal pathogens Aeromonas and Streptococcus reached 105 cells g−1 in the tilapia intestines, while the potential probiotics such as Lactobacillus and Enterococcus with a high concentration of over 106 cells g−1 were detected. Furthermore, PICRUSt analysis revealed that functional genes involved in membrane transport, carbohydrate metabolism, and amino acid metabolism were enriched in the intestinal microbiota of tilapia. This study characterized the intestinal quantitative bacterial ecology of farmed Nile tilapia, providing foundational support for an in-depth understanding of the intestinal microbiota and its interaction mechanism with the host.

中文翻译：

---

通过高通量绝对丰度量化评估养殖尼罗罗非鱼（Oreochromis niloticus）的肠道细菌群落

摘要 基于高通量测序的肠道微生物群研究因其对宿主健康的重要影响而受到越来越多的关注。然而，相对比例的分类概况并不能反映肠道细菌的数量和分类群之间的样本间差异。在本研究中，我们应用了一种高通量绝对丰度定量方法，该方法使用内标菌株同时获得养殖的尼罗罗非鱼（Oreochromis niloticus）肠道细菌群落的相对和绝对丰度。结果表明，加入低浓度内标菌株后，肠道固有菌群的结构、相对和绝对丰度及功能未发生显着变化，并获得了全面的定量肠道细菌生态学。我们首先发现养殖的尼罗罗非鱼肠道固有细菌的总绝对丰度为 2.95 × 108 个细胞 g-1，大多数属的浓度在 103 至 105 个细胞 g-1 的范围内。肠道细菌群落以 Cetobacterium 为主，浓度为 108 个细胞 g-1，其次是 Plesiomonas、Romboutsia 和 Escherichia-Shigella，浓度超过 107 个细胞 g-1。罗非鱼肠道中潜在的肠道病原体气单胞菌和链球菌达到了105个细胞g-1，而潜在的益生菌如乳酸杆菌和肠球菌的浓度超过106个细胞g-1。此外，PICRUSt 分析显示，参与膜转运、碳水化合物代谢、和氨基酸代谢在罗非鱼的肠道微生物群中富集。本研究表征了养殖尼罗罗非鱼的肠道定量细菌生态学，为深入了解肠道微生物群及其与宿主的相互作用机制提供了基础支持。