Characterization of the gut microbiota of yellow catfish (Pelteobagrus fulvidraco) infected with Edwardsiella ictaluri

To reveal the changes in the gut microbiota of yellow catfish after being infected by Edwardsiella ictaluri 16S rRNA gene high-throughput sequencing technology was used to analyze the microbial composition and diversity of the healthy and diseased yellow catfish The gut microbial richness and diversity of the diseased fish were significantly lower than those of healthy fish The composition and predicted function of yellow catfish gut microbiota were drastically altered after infection by E ictaluri Fusobacteriota Proteobacteria and Firmicutes were the predominant bacterial phyla in the gut of the healthy fish while Proteobacteria was the dominant phylum in the gut of the diseased fish At the genus level the gut of healthy fish was dominated by Cetobacterium Plesiomonas and Romboutsia while the gut of diseased fish was overwhelmed by the pathogenic E ictaluriand Cetobacterium Plesiomonas and Romboutsia disappeared This is the most characteristic feature of the intestinal microbiota composition of yellow catfish edwardsiellosis The same sequence of E. ictaluri was detected in the intestine of the healthy and the liver and intestine of the diseased fish The anaerobic and gram-positive bacteria were significantly decreased the digestive system immune system and metabolic functions of the gut microbiota were significantly reduced in the diseased fish gut This may be part of the pathogenesis of fish edwardsiellosis

为揭示迟钝爱德华氏菌（Edwardsiella ictaluri）感染后黄颡鱼肠道菌群的变化，本研究采用16S rRNA基因高通量测序技术，对健康与患病黄颡鱼的肠道微生物组成及多样性进行分析。患病黄颡鱼的肠道微生物丰富度与多样性均显著低于健康个体。感染迟钝爱德华氏菌后，黄颡鱼肠道菌群的组成与预测功能均发生显著改变。健康黄颡鱼肠道内的优势细菌门为梭杆菌门（Fusobacteriota）、变形菌门（Proteobacteria）与厚壁菌门（Firmicutes），而患病黄颡鱼肠道内的优势菌门则为变形菌门。在属水平上，健康黄颡鱼肠道以鲸杆菌属（Cetobacterium）、邻单胞菌属（Plesiomonas）与隆堡菌属（Romboutsia）为优势类群；而患病黄颡鱼肠道则被致病性迟钝爱德华氏菌占据主导，鲸杆菌属、邻单胞菌属与隆堡菌属均消失不见。这是黄颡鱼爱德华氏菌病肠道菌群组成最具特征性的表现。研究还在健康黄颡鱼的肠道中，以及患病黄颡鱼的肝脏与肠道内，均检测到了与迟钝爱德华氏菌一致的序列。患病黄颡鱼肠道内的厌氧菌与革兰氏阳性菌丰度显著降低，肠道菌群的消化、免疫与代谢功能均显著受损。这或为鱼类爱德华氏菌病发病机制的组成部分之一。