›› 2018, Vol. 45 ›› Issue (3): 807-813.doi: 10.16431/j.cnki.1671-7236.2018.03.031

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Isolation and Identification of Edwardsiella tarda in Pelteobagrus fulvidraco and Analysis of Its Pathogenicity

SHI Zhengyu1, YI Yi1, HAN Shuyu2, LUO Fuguang3, HUANG Jie3, LU Jingdi1, LI Ya1   

  1. 1. College of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China;
    2. Guangxi Fishery Technical Extension Station, Nanning 530022, China;
    3. Liuzhou Fishery Technical Extension Station, Liuzhou 545006, China
  • Received:2017-08-21 Online:2018-03-20 Published:2018-03-22

Abstract:

For determining aetiological agent of Pelteobagrus fulvidraco,the pathogen was isolated from the diseased Pelteobagrus fulvidraco and named as GDYM20160809.The isolate was identified by morphological observation,physiological and biochemical characteristics,16S rDNA analysis and phylogenetic tree construction.The susceptibility test of the isolate was carried out by filter paper diffusion method.The results showed that the isolate was gram-negative bacillus and the 16S rDNA fragment was amplified by PCR.The 16S rDNA fragment was sequenced and compared by BLAST,the isolate was 100% homologous to Edwardsiella tarda.Combined with the results of physiological and biochemical identification,the isolate was determined as Edwardsiella tarda.Susceptibility test results showed that the isolate was sensitive to sulfonamides,cephalosporins,penicillins and cotrimoxazole and so on,and was resistant to sodium sulfasalazine,novobiocin,polymyxin B,amikacin,kanamycin and vancomycin six kinds of drugs.The artificial infection test results confirmed that the isolate strain had strong pathogenicity to tilapia,Procypris merus,grass carp and Pelteobagrus fulvidraco.The study provided a theoretical basis for the effective prevention and control of catfish bacterial diseases,and could guide farmers to rational drug use.

Key words: Pelteobagrus fulvidraco; isolation and identification; 16S rDNA; Edwardsiella tarda

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