Microbiome of different intestinal locations of Litopenaeus vannamei

Litopenaeus vannamei represents the most cultivated crustacean species, accounting for approximately 80% of global shrimp aquaculture output. The intestinal microbiota structure and functionality are known to critically influence L. vannamei growth. While previous investigations of shrimp gut microbes emphasized the whole intestine, limited research has examined the composition and functional differences of microbiota across specific intestinal sections in L. vannamei. In this study, healthy shrimp samples were collected and divided into four sections after removing the contents: S(stomach), H (from posterior stomach to the distal end of the hepatopancreas.), G (the section from hepatopancreass end to the sixth abdominal segment), and R(rectum). The microbial composition and function were analyzed across locations via 16S rRNA high-throughput sequencing. The results revealed that significant - and -diversity distinctions existed between sections (p10%) across sections. The rectum pathways including carbon, nitrogen, sulfur metabolisms were significantly elevated. Quorum sensing and two-component systems were also overrepresented in rectum. One-way network analysis showed that the dominant flora of group S, H and G were Bacillus, Mycoplasmataceae, and Flavobacterium, which are promoters of beneficial bacteria in the gut, while the dominant flora of rectumthe most competitive genus of bacteria in the intestinal tract was Vibrio,and Pseudofulvibacter, Alcaligenaceae, and Pseudomonas represent potential probiotic genera that could be screened as antagonists against Vibrio in the shrimp gut. In summary, we hypothesize the stomach and H sections degraded organic matter, G section absorbed and digested macronutrients, and rectum section recycled materials and participated in circular metabolism. These segment-specific analyses provide novel perspectives into section-specific microbial interactions and functions along L. vannamei intestine.

凡纳滨对虾（Litopenaeus vannamei）是全球养殖规模最高的甲壳类物种，约占全球虾类养殖总产量的80%。肠道菌群结构与功能对凡纳滨对虾的生长具有关键调控作用。既往对虾肠道微生物的研究多聚焦于全肠道，而针对凡纳滨对虾特定肠道区段的菌群组成与功能差异的研究相对匮乏。本研究采集健康对虾样本，去除肠道内容物后将肠道划分为四个区段：S（胃）、H（胃后至肝胰腺远端区段）、G（肝胰腺末端至第六腹节区段）以及R（直肠）。通过16S rRNA高通量测序技术分析不同肠道区段的微生物组成与功能，结果显示不同肠道区段间存在显著的α多样性与β多样性差异（p<0.1）。直肠区段的碳代谢、氮代谢与硫代谢通路丰度显著升高，群体感应（Quorum sensing）与双组分系统（two-component systems）通路在直肠区段同样显著富集。单向网络分析结果显示，S、H、G区段的优势菌群分别为芽孢杆菌属（Bacillus）、支原体科（Mycoplasmataceae）与黄杆菌属（Flavobacterium），这些均为肠道有益菌的促生类群；而直肠区段的优势菌群为肠道内竞争力最强的弧菌属（Vibrio），同时假富黄杆菌属（Pseudofulvibacter）、产碱杆菌科（Alcaligenaceae）与假单胞菌属（Pseudomonas）为潜在益生菌属，可被筛选为对虾肠道内弧菌的拮抗菌株。综上，本研究推测胃与H区段负责降解有机质，G区段负责吸收与消化宏量营养素，而直肠区段则参与物质循环与代谢循环。此类肠道区段特异性分析，为凡纳滨对虾肠道内区段特异性的微生物互作与功能研究提供了全新视角。