一株致病性异育银鲫源维氏气单胞菌的分离鉴定

摘要

A bacterial strain was isolated from hepatopancreas of moribund allogenic sliver crucian carp (Carassius auratus gibelio) suffering with severe hemorrhage, characterized using a combination of colonial morphological analysis, physiological and biochemi-cal tests, ultrastructural observation, 16S rRNA and Act enterotoxin genes sequencing, and assessed for pathogenicity by an artificial infection test. Results showed that the isolate is a gram-negative bacterium with rod-shaped, and polar flagella, secreted acid while it developed and grew in the low salinity culture medium containing glucose. Phylogenetic analysis based on 16S rRNA gene sequences showed that it belongs to the genus Aeromonas, with 98% sequence similarity with Aeromonas veronii. PCR investigation revealed there was virulence gene enterotoxin in this strain. An artificial infection tests showed that the strain was pathogenic to hepatopancreas of allogenic sliver crucian carp.%从急性患病异育银鲫 Carassius auratus gibelio 肝胰脏中分离到一株优势菌。对该菌株进行了显微和超微结构观察、生理生化表型鉴定、16S rRNA 和毒力基因分析及人工感染实验。结果显示：分离菌呈短杆状、两头钝圆、端生鞭毛，为革兰氏阴性菌；发酵葡萄糖产酸，氧化酶、触酶试验阳性，高盐浓度不生长；16S rRNA 序列与气单胞菌属 Aeromonas 的基因相似性为98%以上，系统发育分析进一步表明该菌为维氏气单胞菌 A. veronii，在该菌中可检测到肠毒素基因，且回接感染能导致健康银鲫发病，表明该菌具有致病性。