斑点叉尾鮰中一种病原菌的分离与鉴定

目的未知病菌对江苏地区斑点叉尾鮰的养殖业造成了巨大的危害,本文对该地区某养殖场病鱼中分离的细菌进行了鉴定及微生物学特性研究。方法采用VIA培养基分离优势菌株;采用回归感染实验确认病原菌;采用形态学观察、生理生化特征测定、细菌特异性引物PCR扩增检测及细菌基因测序分析鉴定细菌;采用药敏实验测定它对部分抗生素的敏感性。结果从病鱼症状及菌株的培养特性、形态特征与嗜麦芽寡养单胞菌感染斑点叉尾鮰症状十分相似,病鱼有典型的肠套叠和肝脏变性现象。分离菌株为革兰氏阴性杆菌,氧化酶阴性、硝酸还原阴性,不发酵糖类,无动力。最初判为嗜麦芽寡养单胞菌,而经过VITEK2生化及16S rRNA基因系统发育进化显示,与不动杆菌16S rRNA核苷酸同源性最高,为98.7%～99.8%,该菌株为约翰逊不动杆菌。结论分离出的约翰逊不动杆菌grp2580083能导致斑点叉尾鮰患病,症状与嗜麦芽寡养单胞菌感染具有类似性,对渔业养殖造成影响。

Isolation and Characterization of a Pathogenic Bacteria from Channel Catfish,Ictalurus Punctatus

Objective To identify and characterize the unknown pathogenic bacteria from the ill fishes of an aquafarm in Jiangsu Province,causing tremendous harm to the breeding industry of Ictalurus Punctatus separated.Method Dominant bacterial strains were separated by VIA flat;recurrent infection test was employed to confirm the pathogenic bacteria,its physiological-biochemical characteristics were observed and tested by morphology,specific PCR test and germ gene sequence test were used to verify the bacteria;drug sensitivity test was used to test its sensitivity to some antibiotics.Result According to symptoms of ill fishes,the cultural characters,morphological characters,the isolated bacteria strains were initially considered as Stenotrophomonas maltophilia.However,VITEK2 bio-chemical test and 16S rRNA gene sequence analysis,revealed that they had the highest homology with ribonucleotide of acinetobacter 16S rRNA,which is 98.7%～99.8%.The bacteria strains were Acinetobacter.Conclusion Acinetobacter johnsonnie was considered as the pathogenic bacteria for channel catfish(Ictalurus punctatus) in Jiangsu Province.