池塘底泥细菌群落主导凡纳滨对虾肠道细菌群落结构的机制

Shrimps, belonging to the class crustacea, are important aquatic economic animals. Recently, the frequent occurrences of bacterial digestive system diseases, limited the development of the shrimp culture industry. Increasing evidence suggests that the shift of shrimp intestine microbial structure is closely correlated with the bacterial digestive system diseases outbreaks. Thus, it is an important research topic to explore the factors affecting the intestine microorganisms of shrimp. Pacific white shrimp, Litopenaeus vannamei, as one of benthic animals, sediment bacterial community plays the decisive role to bacterial community structure of shrimp intestine cultural ponds. However, the mechanism of sediment community contributes shrimp intestine bacterial community structure remains unexplored. In this project, L. vannamei, was taken as the research object to simulate the establishment of the pond culture system for shrimp, and the relationship between the feeding habits of shrimp and the colonization of sediment bacteria in shrimp intestine was verified by some methods, such as the preparation and transformation of competent cells from bacteria, real-time quantitative PCR, and plate colony-counting methods. In addition, based on 16S rRNA amplicon sequencing, bioinformatics and statistical analysis methods, we assessed the bacterial community composition characteristics and relationship between community in shrimp intestine and sediment across a whole culture-cycle, and clarified the ecological mechanism of sediment community dominate shrimp intestine bacterial community structure. The results of this research can gain a new theoretically understanding of the ecological research of benthic animal intestine microorganisms, and also provide the practical guidance for the healthy culture of L. vannamei.

对虾，隶属于甲壳纲，是重要的水生经济动物。近年来，细菌性消化道疾病频发，限制了全球对虾养殖产业发展。研究表明，对虾肠道微生物群落结构变化与细菌性消化道疾病的发生密切相关；因此，探究影响对虾肠道微生物的因素，是一个重要课题。凡纳滨对虾，作为一种底栖动物，底泥细菌群落对其肠道细菌群落结构起主导作用，但机制未明。本项目拟以凡纳滨对虾为对象，模拟建立池塘养殖系统，并用制备感受态细胞的细菌、实时定量PCR、平板菌落计数等方法，实验验证对虾在底泥摄食习性与底泥细菌在肠道定殖的关系；同时用16S rRNA扩增子测序、生物信息学和统计学分析方法，阐述整个养殖周期中凡纳滨对虾肠道与底泥细菌群落的组成及两者关系的阶段性变化特征，以此阐明底泥细菌群落主导对虾肠道细菌群落结构的生态机制。本项目的研究结果可以从理论上获得对底栖动物肠道微生物生态研究的新认识，也可以从实践上为凡纳滨对虾健康养殖提供指导。

细菌性消化道疾病频发限制了全球对虾养殖产业发展。对虾肠道微生物群落组成变化与细菌性消化道疾病的发生密切相关，故探究其影响因素是一个重要的科学问题和实际问题。环境微生物是影响水生动物肠道微生物的重要因素之一。本项目以凡纳滨对虾池塘养殖生态系统为研究对象，旨在了解对虾肠道与环境的细菌群落之间的关系及其动态变化，以此阐明环境群落影响对虾肠道细菌群落的生态机制。本研究主要发现了：（1）宿主发育过程对对虾肠道细菌群落的演替有重要贡献，确定性过程主导了幼苗阶段对虾肠道群落的装配，而在其他阶段则是以随机性过程为主导；（2）优先效应和环境群落的扩散共同控制了对虾肠道细菌群落的演替，且早期阶段环境群落扩散贡献压倒了优先效应，后期则相反；（3）水体和底泥理化因子可能通过影响环境群落而间接影响对虾肠道细菌群落组成。本项目研究结果可以提高我们对水产养殖微生态的认识及促进对环境影响肠道微生物的理解，也可指导建立对虾健康养殖的微生态防控策略。