微囊藻毒素-LR对凡纳滨对虾肠道菌群及其宿主代谢的影响机理研究

In the middle and late stage of Litopenaeus vannamei culture, microcystins in water easily form dominant populations and produce a large amount of microcystin-LR (MC-LR), which greatly reduces the growth and survival of shrimp. Intestine is an important target tissue for MC-LR. The applicant’s previous studies have found that MC-LR can induce intestine mucosal pathological damage, physiological disorder, and intestine microbial imbalance of L. vannamei. Intestine microbial is involved in host metabolism, and both of them have the characteristics of co-variation. Accordingly, the applicant put forward the hypothesis that the imbalance of intestine microbial induced by MC-LR affects the host metabolic function, and there are functional microbial related to metabolism. Therefore, the object of this project is to establish the intestine pathological model of L. vannamei induced by MC-LR, analyze the effects of MC-LR on intestine microbial structure and metabolic function of shrimp by metagenomic and metabonomic techniques, reveal the metabolic changes of shrimp induced by MC-LR, and finally reveal the co-variation characteristics of intestine microbial and host metabolism by multivariate statistical methods, and identify and preliminary analysis the important functional bacteria responding to MC-LR. The results are helpful to elucidate the mechanism of the effects of MC-LR on the intestine microbial and host metabolism of L. vannamei. Meanwhile, the functional strains identified in this study will drive the development of microbial agents against MC-LR stress in L. vannamei.

微囊藻是凡纳滨对虾养殖中常见的有毒藻类，其产生的微囊藻毒素-LR（MC-LR）严重影响对虾生长和存活。肠道是MC-LR毒性作用的重要靶组织之一。申请人前期研究发现，MC-LR诱导凡纳滨对虾肠道黏膜病理损伤、生理紊乱以及肠道菌群失衡。文献证实，肠道菌群参与宿主代谢，二者具有共变化特征。据此申请人提出假说“MC-LR诱导凡纳滨对虾肠道菌群失衡影响其宿主代谢功能，并存在与代谢相关的功能菌群”。拟通过建立MC-LR诱导的凡纳滨对虾肠道病理模型，利用宏基因组和代谢组学技术分析MC-LR对对虾肠道菌群结构和代谢功能的影响，揭示MC-LR诱导对虾机体代谢的变化规律；最后结合多元统计学方法揭示肠道菌群与宿主代谢的共变化特征，鉴定和初步分析响应MC-LR的重要功能微生物。研究结果有助于从肠道菌群-宿主代谢角度阐释MC-LR对凡纳滨对虾的毒性机制，亦可推动凡纳滨对虾防御MC-LR胁迫的微生物制剂开发进程。

凡纳滨对虾养殖水体富营养化易导致有害蓝藻成为优势，其产生的微囊藻毒素-LR（MC-LR）严重影响对虾生长、免疫和存活。肝肠是对虾营养和免疫的主要场所，也是MC-LR毒性作用的靶器官。肠道菌群变化影响宿主生理，二者存在共变化特征。本项目通过解析MC-LR胁迫下凡纳滨对虾肠道菌群结构和功能、肝胰腺生理功能的变化特征，揭示肠道菌群与宿主免疫代谢的相关性，鉴定响应MC-LR胁迫的肠道细菌和代谢标志物，并探究关键代谢物在凡纳滨对虾免疫应答中的作用。主要研究结果如下：1）MC-LR胁迫导致对虾肠道组织损伤与免疫指标紊乱，诱导肠道微生物多样性升高、有益菌群丰度降低，造成肠道氨基酸生物合成、蛋白质消化和吸收等功能改变；肠道菌群主要通过增强ABC转运体、核黄素代谢以及碳水化合物代谢酶等功能应答胁迫。2）MC-LR胁迫诱导对虾肝胰腺组织病理变化，导致模式识别受体紊乱、酚氧化酶原系统激活、解毒代谢（CYPs-GST-MRP1）通路下调，以及柠檬酸循环、氨基酸、亚油酸和花生四烯酸代谢功能变化；降低肝胰腺脂肪消化酶活性，激活长链脂肪酸β-氧化基因转录，进而影响脂质代谢和脂质稳态。3）MC-LR诱导的对虾肠道菌群变化与其宿主免疫和代谢具有相关性，进一步揭示了肠道菌群变化会影响健康对虾的免疫稳态。4）饲喂花生四烯酸可以提高凡纳滨对虾对MC-LR胁迫的免疫应答，改善肠道菌群结构，提高有益菌（拟杆菌属和乳酸杆菌属）丰度。本项目揭示了MC-LR对凡纳滨对虾肠道菌群及其宿主生理的影响机理，鉴定到的肠道细菌和代谢物有助于驱动对虾生物制剂研发进程。