哈维弧菌对珍珠龙胆石斑鱼肠道菌群的调控及壳寡糖的干预机制研究

珍珠龙胆石斑鱼是我国重要的海洋经济鱼类。近年来细菌性疾病的频发，对石斑鱼的养殖业造成巨大损失。哈维弧菌是珍珠龙胆石斑鱼细菌性肠炎的主要病原之一，对肠道菌群的调控机制尚不清楚。壳寡糖，作为海洋益生元，具有多种生物活性功能，但其对弧菌感染珍珠龙胆石斑鱼的干预调控机制仍未解读。申请人前期研究发现，通过体外和体内模型证明壳寡糖的生长与免疫调节功能。本项目拟以“肠道菌群-转录信号-代谢通路”为靶标研究哈维弧菌对石斑鱼的肠道菌群调控及壳寡糖的干预作用，通过建立EGFP标记弧菌感染模型，研究肠道细菌定植情况及壳寡糖的免疫保护机制；揭示弧菌感染和壳寡糖干预作用下，珍珠龙胆石斑鱼肠道菌群的结构组成、多样性及动态平衡调控机制；探明弧菌感染和壳寡糖的互作机制及在免疫应答过程中的关键基因和转录信号通路；阐述壳寡糖回补干预对差异代谢物及代谢通路的影响。研究结果将为壳寡糖的应用提供参考，也为海洋鱼类健康养殖提供新思路。

Hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatu ♂) is the most important marine economic fish in China. The outbreaks of various bacteriosis in recent years have already caused great economic loss in the grouper culture. Vibrio harvey is one of the main pathogens causing bacterial enteritis of hybrid groupers, but the understanding of its regulation of intestinal microbiota is still scarce. Chitooligosaccharides are known marine prebiotics which possess many bioactive functions, but the underlying mechanism in hybrid grouper under V. harvey infection remains enigmatic. The applicant's previous studies have confirmed that chitooligosaccharides can promote the growth and immunity of the body through in vitro and in vivo models. The aim of this project is to study the intestinal microbiota regulated by V. harvey and the intervention effect of chitooligosaccharides on hybrid grouper with the target of intestinal flora, transcriptional signal and metabolic pathway. The colonization of intestinal bacteria will be elucidated by establishing the infection model of EGFP-labeled V. harvey. The community composition, diversity and dynamic balance mechanisms of intestinal microbiota in hybrid grouper will be explored via challenged with V. harvey and fed with chitooligosaccharides. Differentially expressed genes and immune signal pathways will be identified to reveal the interaction mechanism between V. harvey infection and chitooligosaccharides intervention in hybrid grouper. To further illustrate the effect of chitooligosaccharide supplement intervention, differential metabolic markers and metabolic pathways will be screened. Taken together, the results will provide insight to its application of chitooligosaccharides, thus offering an aspect to healthy culture of marine groupers.