1株草鱼源温和气单胞菌的分离与鉴定

Isolation and Identification of an Aeromonas sobria from Ctenopharyngodon idellus

【目的】从养殖患病草鱼组织中分离致病菌,为预防该菌所引起的水产动物疾病提供参考依据。【方法】从患病草鱼肠中分离得到1株菌CQWL0012,进行分离菌株的形态学特性、培养特征、生化特征、16Sr DNA鉴定,并开展药敏试验。【结果】CQWL0012为两末端钝圆的短杆革兰氏阴性菌,菌落表现为浅黄色、半透明、表面光滑、略凸、边缘整齐;16SrDNA阳性产物序列长度为1422 bp,与温和气单胞菌相似率达99.85%;赖氨酸脱羧酶、精氨酸双水解酶等生理生化试验阳性,符合气单胞菌属的生理生化特征,确定该菌株为温和气单胞菌(Aeromonas sobria);对草鱼的半致死浓度LD_(50)为10^(6.73)。该菌对四环素、庆大霉素、磷霉素、氯霉素、氨曲南、环丙沙星等13种抗生素高度敏感。【结论】引起草鱼患病的菌株CQWL0012为温和气单胞菌(Aeromonas sobria),对四环素、庆大霉素等常见抗生素高度敏感。

【Objective】A pathogen was isolated from tissues of farmed and sick Ctenopharyngodon idellus,which provided reference for preventing the disease of aquatic animals caused by this pathogen.【Method】A bacterial strain,CQWL0012,was isolated from the gut of sick C.idellus,then this bacterial strain were identified from the morphology,cultural characteristics,biochemical feature and 16SrDNA sequence,and the drug sensitive test was conducted.【Result】CQWL0012 was a short rod-shaped Gram-negative bacterium with two blunt round ends.The bacterium was light yellow,translucent,slightly convex,and had smooth,slightly bulgy surface and neat edge.The sequence of 16SrDNA positive product was 1422 bp,which was highly homologous with Aeromonas sobria with the similarity rate of 99.85%.The physiological and chemical experiments of lysine decarboxylase,arginine dihydrolase both showed as positive,which was consistent with the physiological and chemical characteristics of A.sobria.Thus CQWL0012 was determined as A.sobria,and its median lethal dose(LD_(50))to C.idellus was 10^(6.73).A.sobria was highly sensitive to 13 kinds of antibiotics,such as tetracycline,gentamicin,fosfomycin,chloramphenicol,aztreonam,ciprofloxacin,etc.【Conclusion】CQWL0012 that causes C.idellus to get sick is A.sobria,and it is highly sensitive to tetracycline,gentamicin and other antibiotics.