Isolation and identification of bacterial pathogen and histopathological change in skin ulcer disease of Chinese snakehead Channa argus
YU Dapeng, TANG Huaiqing, QIU Jinzhu, SONG Haixia, LIANG Fu, XIA Hongli, SONG Changjiang, LU Yishan
1.Shenzhen Research Institute, Guangdong Ocean University, Shenzhen 518108, China; 2.College of Fisheries, Guangdong Ocean University, Zhanjiang 524088, China; 3.Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Shenzhen 518108, China; 4.Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen 518108, China; 5.Agricultural Products Quality & Safety Testing Institute of Zhongshan, Zhongshan 528437, China
Abstract: In order to explore the etiology and histopathological changes in skin ulcer disease of Chinese snakehead Channaargus, a dominant bacterial strain (designated as ZS20200317) was isolated from the diseased Chinese snakehead collected from Zhongshan, and identified through the analysis of morphological characters, Gram staining, 16S rRNA gene, physiological and biochemical characters. The health Chinese snakehead was challenged with the isolated bacterium ZS20200317 for the confirmation whether the isolated bacterium was the causative bacterium for the diseased fish, and then sensitivity of the isolated bacterial strain ZS20200317 to 30 types of antibiotics was also tested. The results showed that the ZS20200317 was a Gram-negative bacterium with white colony of smooth edge and luster when cultured on the LB agar plate. The phylogenetic analysis of 16S rRNA indicated that ZS20200317 had the closest relationship with Aeromonasveronii, shared 98.5% similarities. Sensitive test of the bacterium showed that the strain had highly sensitive to 20 kinds of antibiotics, including chloramphenicol, ceftazidime, cefalexin, cefazolin and cefradine floxacin, had strong effects on the bacterium, and resistant to 7 kinds of drugs, such as ampicillin, oxacillin, carboxybenzillin, penicillin G, Medicin, vancomycin and clindamycin. Artificial regression infection showed that the bacterial strain led to the death of Chinese snakehead. The findings indicated that A.veronii was the pathogen of skin ulcer of Chinese snakehead in Guangdong Province, which will provide some reference basis for the prevention and control of disease induced by A.veronii in Chinese snakehead culture.
2021, Vol. 36 
