Isolationof Edwardsiella tarda from cultured hybrid snakeheads (Channa maculata♀C.argus♂) and its identification

Two pathogenic bacteria (ZS201364-1，ZS201364-2) isolated from diseased hybrid snakeheads (Channa maculata♀C. argus♂) were identified to be Edwardsiella tarda by analyses of biochemical features and 16S rDNA sequence. The anaerobic, gram negative, bacilliform and motile isolates utilized glucoses and maltose as energy.Both indole and M.R. tests proved positive. The LD50s of the isolates to healthy hybrid snakeheads were 7.1105 cfug-1and 5.6105 cfug-1, respectively. The optimal growth conditions of strain ZS201364-1, which was highly susceptible to cefotaxime, ciprofloxacin and norfloxacin, were 25~35 ℃, pH 7~8 and 1% NaCl.