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为鉴定长春市某水产养殖基地患病团头鲂(Megalobrama amblycephala)病原菌,本研究从患病鱼中分离出致病菌WC03株,经人工感染试验鉴定该病菌有较强的致病性,能使团头鲂、小鼠及斑马鱼致病死亡,之后对分离菌株WC03进行形态学、理化特性分析,初步判定该菌为嗜水气单胞菌。进一步使用分子生物学方法检测该菌16S r DNA和gyr B、rpo D和cpn60这3种管家基因,同时对该菌的致病性及毒力基因携带情况进行分析。结果显示,16S r DNA及管家基因系统进化分析表明,该菌与嗜水气单胞菌聚类,且同源性在98%以上。该菌含有气溶素(aer)、细胞毒性肠毒素(act)、黏附素(aha)、丝氨酸蛋白酶(Ser)、核酸酶(exu)、脂肪酶(Lip)及密度感应系统调控基因(Luxs)这7种毒力因子。药敏试验结果表明,该菌对呋喃妥因、头孢噻肟、头孢噻吩、头孢呋辛这4种药物高度敏感。
In order to identify the pathogen of Megalobrama amblycephala in an aquaculture base in Changchun City, the pathogen WC03 was isolated from the diseased fish and the pathogen was identified by artificial infection test. After the death of the head, mouse and zebrafish, the morphological and physicochemical properties of the isolated strain WC03 were analyzed, and the strain was determined to be Aeromonas hydrophila. The molecular biology method was used to detect the 16S r DNA and the gyr B, rpo D and cpn60 three housekeeping genes of the bacteria, and pathogenicity of the bacteria and virulence gene carrier situation analysis. The results showed that the phylogenetic analysis of 16S r DNA and housekeeping genes showed that the bacteria clustered with Aeromonas hydrophila and the homology was over 98%. The bacterium contains aer, actin, aha, ser, exu, lip and Luxs, These seven virulence factors. Susceptibility test results show that the bacteria on nitrofurantoin, cefotaxime, cefalotin, cefuroxime highly sensitive to the four drugs.