海水网箱养殖许氏平鲉细菌性疾病病原鉴定及致病性研究

2019年8月,大连市金州区大李家街道海域海水网箱养殖许氏平鲉(Sebastes schlegeli)暴发严重的皮肤溃疡性疾病。以其为研究对象,从体表病灶、肝脏和肾脏上进行细菌分离,得到1株优势菌株BN-1910。为了验证网箱养殖许氏平鲉死亡是否由该菌株引起,采取腹腔注射的方式进行该菌株回感,以确定该菌株的致病力。在对菌株进行生理生化检验和形态学观察后,可以初步判断菌株为哈维氏弧菌(Vibrio harveyi)。基于16S rRNA基因序列构建的分子系统发生树表明,哈维氏弧菌(MT864681.1)和该菌株在系统发育树中聚为一支,99%置信水平。研究结果显示,菌株BN-1910为哈维氏弧菌(V.harveyi),对许氏平鲉10 d的LD50为7.98×10^3 CFU/mL;对14种药物的敏感试验证实,菌株BN-1910对氟哌酸、链霉素和左氧氟沙星敏感。

Pathogen Identification of bacterial disease in marine cage cultured Sebastes Schlegeli and the study of pathogenicity

There was a serious outbreak of skin ulcer disease in marine cage cultured Sebastes schlegeli in Dalijia Street,Jinzhou District,Dalian in August,2019.By using the diseased S.schlegeli as the object of study,a dominant strain of BN-1910 was isolated based on bacteria isolation from its surface lesion,liver and kidney.In accordance with the results of re-infection experiment using intraperitoneal injection,it was confirmed that the isolated strain had strong virulence and could induce the disease onset and death of the cultured S.schlegeli.The strain isolated was the pathogenic bacterium of the skin ulcer at this time.Further morphological observation and physiological-biochemical property analysis identified that the pathogen was V.harveyi.Meanwhile,the phylogenetic tree based on the 16S rRNA gene indicated that the isolated strain and V.harveyi(MT864681.1)clustered into one branch,with the degree of confidence to be 99%.Findings in our study supported that the strain BN-1910 was V.harveyi,and the LD50 of 10 d to S.schlegeli was 7.98×10^3 CFU/mL.In addition,sensitivity test of the strain of 14 types of drugs confirmed that BN-1910 was sensitive to Norfloxacin,Streptomycin and Levofloxacin.