Pseudomonas aeruginosa is a common gram-negative pathogen belonging to the Aeromonas genus. In the present study, dominant bacteria were isolated from diseased crucian carp (Carassius auratus gibelio). The isolate was identified as P. aeruginosa based on biochemical identification and 16S rDNA sequencing. In the histological observation of diseased C. auratus, a large number of vacuoles and inflammatory infiltration appeared in the liver, the structure of intestinal villi was loose, and a large number of inflammatory cells and vacuoles were found in gill. Five virulence genes exoU, exoS, pcrV, exoT and exoY were identified in this P. aeruginosa isolate. Drug sensitivity testing showed that the isolate was susceptible to norfloxacin, ofloxacin and ciprofloxacin. The supernatant of Bacillus coagulans NJ3 exhibited a significant bactericidal effect on isolated P. aeruginosa based on the inhibition zone experiment. The accumulative mortality of C. auratus caused by P. aeruginosa infection could be significantly reduced by adding B. coagulans NJ3 into the aquaculture water. These results indicated that B. coagulans NJ3 could be used as probiotics to prevent the infections of P. aeruginosa in C. auratus. The present study provided a scientific basis for the identification of P. aeruginosa, and treatment for this pathogen infections in fish by using B. coagulans NJ3.

铜绿假单胞菌是一种常见的革兰氏阴性病原体，属于气单胞菌属。本研究从病鲫（Carassius auratus gibelio）中分离出优势菌。基于生化鉴定和16S rDNA测序，分离株被鉴定为铜绿假单胞菌。患病金鱼的组织学观察，肝脏出现大量空泡和炎性浸润，肠绒毛结构疏松，鳃内可见大量炎性细胞和空泡。五个毒力基因exoU , exoS , pcrV , exoT和在这种铜绿假单胞菌分离物中鉴定出exoY。药敏试验表明分离株对诺氟沙星、氧氟沙星和环丙沙星敏感。基于抑菌圈实验，凝结芽孢杆菌NJ3上清液对分离的铜绿假单胞菌表现出显着的杀菌作用。在养殖水体中加入凝结芽孢杆菌NJ3可显着降低铜绿假单胞菌感染引起的C. auratus累积死亡率。这些结果表明，凝结芽孢杆菌 NJ3 可作为益生菌预防铜绿假单胞菌感染C. auratus. 本研究为鉴定铜绿假单胞菌以及利用凝结芽孢杆菌NJ3治疗鱼类感染该病原菌提供了科学依据。