Abstract:
In 2013,the large yellow croaker (
Larimichthys crocea) cultured in net cage at Ningde was diseased.The sick fish appeared symptoms of gill filaments ulcers and gill rakers bare.One dominant bacterial strain,named as Lc-2013-G1,was isolated from the gill of sick
L.crocea.The strain Lc-2013-G1 was confirmed to be a bacterial pathogen of
L.crocea by artificial infection.Physiological and biochemical characteristics showed that the pathogen Lc-2013-G1 formed a smooth,moist,marginally yellow colony on the TCBS medium,which was Gram-negative and arc-shaped rod.The strain Lc-2013-G1 had motility and grew in a medium containing 6% sodium chloride.The indicators of V-P,arabinose,sputum matrix and citrate were negative to Lc-2013-G1,while the indicators of galactose,catalase and amylase were positive to Lc-2013-G1.The pathogen Lc-2013-G1 was determined to be
Vibrio ponticus based on morphological and physiological detection,biochemical tests and 16S rRNA gene analysis.Antibiotic sensitivity analysis indicated that the pathogen Lc-2013-G1 was sensitive to Ampicillin,Polymyxin B,Sulfamethoxazole,Norfloxacin,Piperacillin,Gentamycin,Cefoperazone,Ofloxacin,and so on.The results provided a reference for the prevention and treatment of large yellow croaker disease caused by Vibrios.