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为探明发病怀头鲶Silurus soldatovi的病原及其生物学特征,从发病怀头鲶体内分离出1株革兰氏阴性细菌SG-1,通过细菌形态学观察、理化特性、16S r DNA测序和构建系统发育进化树分析对其进行了鉴定。结果表明:分离菌SG-1菌株葡萄糖产气、氧化酶、硝酸盐还原为阳性,鸟氨酸脱羧酶、硫化氢为阴性;进一步采用PCR方法扩增其16S r DNA序列,测序获得片段大小为1409 bp,与维氏气单胞菌Aeromonas veronii模式菌株ATCC35624序列相似性达99.86%;构建系统发育树分析显示,分离菌与维氏气单胞菌自然聚为一支,最终判定SG-1菌株为维氏气单胞菌;人工感染斑马鱼Danio rerio、鲶S.soldatovi,其死亡率均达100%,病鱼呈现体表出血、肛门红肿、腹水等症状;药敏试验结果显示,该菌对头孢克肟、头孢哌酮、头孢噻肟、诺氟沙星、左氟沙星、恩诺沙星、氟苯尼考等药物敏感,对阿莫西林、氨苄西林、磺胺异恶唑、甲氧嘧啶、复方新诺明等耐药。本研究结果为了解维氏气单胞菌感染鲶的致病机理及其该病的预防治疗提供了科学参考。
To identify the pathogen and its biological characteristics of Silurus soldatovi, one Gram-negative bacterium SG-1 was isolated from the diseased catfish. Bacterial morphology, physical and chemical properties, 16S rDNA sequencing and It was identified by constructing phylogenetic tree analysis. The results showed that the 16S r DNA sequence of PCR-amplified 16S r DNA sequence of SG-1 isolates were positive for glucose gas production, oxidase and nitrate reduction, and the ornithine decarboxylase and hydrogen sulfide were negative. The fragment size 1409 bp and 99.86% similarity to Aeromonas veronii model strain ATCC35624. The phylogenetic tree analysis showed that the isolates were naturally clustered together with Aeromonasviviridae, and finally the strain SG-1 Is Aeromonas sobria; artificial infection of Danio rerio, catfish S. soldatovi, the mortality rate reached 100%, diseased fish showed body surface bleeding, anal swelling, ascites and other symptoms; susceptibility test results show that the bacteria Of cefixime, cefoperazone, cefotaxime, norfloxacin, levofloxacin, enrofloxacin, florfenicol and other drugs sensitive to amoxicillin, ampicillin, sulfisoxazole, a Oxygen pyrimidine, cotrimoxazole and other drug resistance. The results of this study provide a scientific reference for understanding the pathogenesis of Aeromonas sobria infection and prevention and treatment of the disease.