健康和患病凡纳滨对虾幼虾消化道菌群结构的比较

Comparison of the bacterial community structures between healthy and diseased juvenile shrimp(Litopenaeus vannamei) digestive tract

凡纳滨对虾养殖过程中,早期阶段是病害易感阶段,而消化道菌群结构与对虾健康关系密切。因此,探讨幼虾的消化道菌群尤其是弧菌类细菌与对虾发病的关系对病害有效防治具有重要意义。本实验采用Illumina测序研究了凡纳滨对虾健康和患病幼虾的消化道细菌群落结构,并基于纯培养和16S r DNA,rec A和pyr H基因序列比对,分析了幼虾消化道中弧菌的主要种类组成。结果发现,健康幼虾消化道中α-变形菌纲和厚壁菌门丰度较高,而患病幼虾中γ-变形菌纲、拟杆菌门、放线菌门和β-变形菌纲较高,其中放线菌门丰度差异显著。基于科水平的响应比分析,发现患病幼虾消化道中动性球菌科和噬菌弧菌科的丰度显著降低,而弧菌科的丰度显著升高。相似度分析发现,驱动群落变异的OTU主要来源于弧菌属、海洋杆状菌属、冷杆菌属、假交替单胞菌属以及未分类至属的红杆菌科和微杆菌科。健康幼虾消化道弧菌组成以锡那罗亚州弧菌为主,而患病幼虾消化道弧菌组成以坎氏弧菌为主。尽管健康和患病幼虾消化道内细菌群落结构整体差异不显著,但一些重要类群丰度变化显著,其特征与已知的生态功能一致。

The early stage of shrimp aquaculture is susceptible to bacterial infection and the bacterial community structure in digestive tract is highly associated with shrimp health. Therefore, it is of great significance to explore the relation between shrimp bacterial community of digestive tract and juvenile shrimp disease. We investigated the intestinal bacterial community composition of healthy and diseased juvenile shrimp（Litopenaeus vannamei） by using Illumina sequencing, and explored Vibrio diverstiy based on 16 S r DNA, rec A and pyr H gene sequences of Vibrio isolates. The results showed that the average relative abundances of Alphaproteobacteria and Firmicutes are higher in healthy juvenile shrimp digestive tract than those in diseased one, while these of Gammaproteobacteria,Bacteridetes, Actinobacteria and Betaproteobacteria exhibited an opposite pattern and the variation in Actinobacteria is significant. In addition, response ratio analysis at the bacterial family level shows that the relative abundances of Planococcaceae and Bacteriovoracaceae families significantly decreased, while that of Vibrionaceae remarkably increased in diseased juvenile shrimp digestive tract in relation to healthy one. Similarity percentage（SIMPER） analysis revealed that the main contribution to the variation of intestinal bacterial community structure between healthy and diseased shrimp is attributed to 8 OTUs affiliated with Vibrio, unclassified Rhodobacteraceae,Marivita, Cryobacterium, unclassified Microbacteriaceae and Pseudoalteromonas. As to Vibrio assamblege composition, we found that culturable V. sinaloensis strains were the dominant species in healthy juvenile shrimp digestive tract, while V. campbellii is dominant in diseased juvenile shrimp.