大菱鲆出血性败血症病原菌的分离与鉴定

Isolation and identification of haemorrihagic septicaemia pathogen from cultivated turbot Scophthalmus maximus

从全身呈弥漫性出血的养殖大菱鲆Scophthalmus maximus肝脏、腹水和肾脏中分离到3株菌落形态相同的优势菌,取菌株L-59231通过注射(菌液浓度分别为4×108、5×107cfu/mL,剂量0.1 mL/尾)、灌喂(4×106cfu/mL,0.5 mL/尾)和创伤浸泡(4.7×105cfu/mL)三种途径对大菱鲆进行人工感染试验。结果表明:以上三种途径均可造成大菱鲆的发病,灌喂感染和创伤浸泡对试验鱼的感染率为100%和57.1%,未发现死亡;注射感染的死亡率分别为100%和71.4%。药敏试验表明,庆大霉素、四环素、氯霉素、红霉素、链霉素等对L-59231菌株有较强的抑制作用。该菌呈短杆状,革兰氏染色阴性,氧化酶阳性,接触酶阴性,V-P试验阴性,硝酸盐还原反应阳性。根据《常见细菌系统鉴定手册》所描述的弧菌属的生理生化特性,综合形态观察、生理生化特征、16S rRNA基因序列等试验结果,可将L-59231菌株鉴定为创伤弧菌。

Three strains of bacteria with same morphological colony were isolated from cultured turbot Scophthalmus maximus suffered from haemorrihagic septicaemia all over the body, and numbered as L -49231, L -59231 and L -59232. The artificial challenge experiments including intramuscular and marinating challenge and oral administration were carried out with L -59231. The results showed that the turbot was infected by L -59231 through three pathways in which the oral challenge pathways had 100% of infection rate. There were 100% and 71.4% mortality in intramuscular challenge and no mortality in oral challenge and marinating pathway. The marinating pathways had 57.1% of infection rate. This bacterium was showed to be gram negative, short - rod shape, oxidase positive, catalase negative, V.P. test negative, and nitrate reduction . physiological and biochemical characteristics according system of common bacterium＇. positive. L -59231 was identified as Vibrio vulnificus by its to the description of ‘The identification handbook on the system of common bacterium＇.