【摘要】 为了探讨2020年初吉林省查干湖分支甩湾子出现鲢大面积死亡现象的原因，从发病鲢中分离纯化出1株具有生长优势的菌株，并对分离菌株进行细菌形态观察和生理生化试验，用16SrDNA和管家基因的序列分析进行分子水平鉴定及系统进化树分析，之后对分离株进行携带毒力基因情况、生长曲线测定、人工感染试验及药敏试验。结果显示，分离菌株为革兰氏阴性，鼠李糖、卫矛醇半固体、ONPG、甘露醇、丙二酸盐、阿拉伯糖、乳糖、赖氨酸脱羧酶、氨基酸脱羧酶、明胶为阳性。综合生理生化试验、16SrDNA及管家基因的鉴定，可判断分离株隶属于豚鼠气单胞菌。通过对分离菌株毒力基因PCR结果表明，分离菌株携带7种毒力基因，其对斑马鱼以及鲢的半数致死量分别为2.51×10~2 CFU和2×10~4 CFU，证明其具有强致病性。分离菌对青霉素、苯唑西林、氨苄西林、羧苄西林、头孢氨苄、米诺环素、头孢他啶、克林霉素、麦迪霉素、万古霉素、头孢拉定、头孢唑啉耐药，说明属于多重耐药菌株。更多还原

【Abstract】 In order to explore the reason for the large-scale death of silver carp at the beginning of 2020 in Chagan Lake branch of Jilin Province,the experiment was conducted to isolate and purify a strain with growth advantages from diseased silver carp,and then conduct morphological observation and physiological and biochemical tests on the isolated strain for the preliminary identification,and use 16 SrDNA and housekeeping gene sequence analysis to carry out molecular level identification and phylogenetic tree analysis,and then carry out the virulence gene status,growth curve determination,artificial infection test and drug susceptibility test on the isolates.The results showed that the isolated strain was Gram-negative.The tests of rhamnose,dulcitol semi-solid,ONPG,mannitol,malonate,arabinose,lactose,lysine decarboxylase,amino acid decarboxylase,and gelatin were positive.Through the comprehensive physiological and biochemical tests,16 SrDNA and housekeeping gene identification,it can be judged that the isolate belongs to Aeromonas caviae.The PCR results of the virulence genes of the isolated strain showed that the isolated strain carried 7 virulence genes,and their median lethal doses to zebrafish and silver carp were 2.51×10~2 CFU and2×10~4 CFU,respectively,indicating the strain is highly pathogenic.Moreover,the results of the drug susceptibility test showed that the isolate was only highly sensitive to piperacillin,doxycycline,cefoperazone,amikacin,tetracycline,kanamycin,furazolidone,gentamicin,neomycin,norfloxacin,ofloxacin,ciprofloxacin,and chloramphenicol,indicating that the isolated strain is multi-drug resistant strain.更多还原