齐口裂腹鱼溃疡病病原的分离鉴定

从患溃疡病的齐口裂腹鱼(Schizothorax prenanti)的溃疡灶中分离到一高致病性菌株D060501,动物回归实验证实该菌能引起健康齐口裂腹鱼出现明显的体表溃疡症,且具有较强的致病作用。通过对分离菌进行了形态学、理化特性等较系统的表观分类学指征鉴定,该菌菌株在TSA平板上生长呈边缘光滑、有光泽的圆形白色菌落,具有溶血性。染色发现该菌为革兰氏阴性短杆菌;具运动性;能发酵葡萄糖;脂酶、氧化酶和精氨酸双水解酶反应阳性;能利用葡萄糖产气,阿拉伯糖产酸;麦芽糖、硫化氢、氰化钾和V-P反应阳性;DNA酶和尿素反应阴性。对该菌的16S rDNA进行PCR扩增、克隆及测序,得到1条长度为1 514 bp的核苷酸序列。将获得的序列在GenBank数据库中进行Blast分析并下载同源性较高的细菌序列,用DNAstar软件进行多序列比对分析并构建系统发育树,结果表明,D060501分离株与其他嗜水气单胞菌形成一个簇群,菌株D060501与嗜水气单胞菌(Genbank登录号AF468055)的亲缘关系最近,同源性高达为99.1%,由D060501菌株的系统进化树分析可见,该菌与其他7株菌在进化上距离小于1.0,结合形态及生理生化特点可将其鉴定为嗜水气单胞菌。对该菌的药敏试验表明,该菌对氯霉素和庆大霉素高度敏感,对四环素、复方新诺明、强力霉素和羧苄青霉素耐药。

Isolation and Identification of Etiology of Skin Ulcer in Schizothorax prenanti

A highly pathogenic pathogen D060501 was isolated from the diseased Schizothorax prenanti with typical skin ulcer,and animal experiments confirmed that the bacteria can cause obvious surface ulcer disease on health Schizothorax prenanti and have a strong pathogenic effect.Through the apparent taxonomic identification of morphological,physiological and biochemical characteristics,the bacteria strains were grown smooth edges and shiny circular white colonies with haemolyticus.The staining found the bacteria were Gram-negative brevibacterium with the features of the mobility,fermentation of glucose,lipase,oxidase and arginine double-hydrolase positive reaction,making use of glucose to produce gas,arabinose to produce acid,sulfureted hydrogen,potassium cyanide and V-P positive reaction,negative reaction of DNA enzymes and urea.The 16S rDNA of the bacteria was amplified,cloned and sequenced,a length of 1 514 bp nucleotide sequence were obtained,which were Blast in GenBank and downloaded the high homology bacterial sequence,then the sequences were aligned,analyzed and constructed the phylogenetic tree.The results showed that D060501 and other Aeromonas hydrophila(Genbank accession number AF468055) forms a cluster and have the closest relationship with the 99.1% homology.According to the phylogenetic tree,the evolutionary distance between D060501 strain and other seven strain is less than 1.0 and it can be identified as Aeromonas hydrophila based on its morphological and physiological characteristics.Sensitive test of the bacteria showed that the strain highly sensitive to chloramphenicol and gentamicin but resist to tetracycline,cotrimoxazole,doxycycline and carbenicillin.