一株东北林蛙源嗜水气单胞菌鉴定及其致病性

Identification and Pathogenicity of Aeromonas hydrophila from Rana dybowskii

在黑龙江省伊春林区捕获的呈"红腿病"体征的东北林蛙(Rana dybowskii),从其肝脏和腹腔积液中分离出一致病菌株RY-1,通过对分离菌株形态特征、生理生化、16 S rDNA基因序列和系统发育树等分析进行菌种鉴定,并用该菌株RY-1人工感染健康东北林蛙后观察其肝脏组织病理学变化。结果显示,菌株RY-1形态呈浅黄色有光泽的圆形、中央凸起、边缘光滑、直径为1.5～2 cm的菌落,革兰氏染色阴性,16S rDNA的系统发育树等结果分析判定为嗜水气单胞菌(Aeromonas hydrophila)。随着感染时间延长(12～72 h),肝细胞变性,呈空泡样变,细胞间隙增大,炎性细胞浸润逐渐明显。本研究分离并鉴定了1株东北林蛙源嗜水气单胞菌,并首次探讨了人工感染嗜水气单胞菌的东北林蛙病理学变化,对其疾病防控和健康养殖具有重要参考意义。

One Dybowski s frog Rana dybowskii showing the“red-legged”symptom was captured in the Yichun forest area of Heilongjiang Province.A pathogenic strain RY-1 was isolated from its liver and ascetic fluid.The isolated strain was identified by analysis of its morphology,physiological and biochemical characteristics,16S rDNA sequence and phylogenetic tree.The histopathological changes of the liver were observed with the strain RY-1 after the induced infection.The colony of the strain was pale yellow and glossy,circular,showing a central bulge and smooth edge,1.5-2 cm in diameter,and gram staining was negative.It was identified as Aeromonas hydrophila by phylogenetic analysis of its 16S rDNA sequence.With the duration of infection(12-72 h),liver cells degenerated and vacuolated,cell gaps increased,and inflammatory cell infiltration gradually became obvious.In this study,we isolated and identified one strain of A.hydrophila sourced from R.dybowskii.The pathological changes of R.dybowskii following induced infection with A.hydrophila are here discussed for the first time.This information might be applied to the prevention and control of the disease and to healthy farming.