赤点石斑鱼的普通变形菌病原学研究  

Pathogenic Proteus vulgaris Found in Redspotted Grouper Epinephelus akaara

作　　者：杨霞[1] 吴信忠[1] 

机构地区：[1]中国科学院南海海洋研究所,广东广州510301

出　　处：《水产科学》2005年第9期5-7,共3页Fisheries Science

基　　金：国家自然科学基金资助项目(NO.3059781NO.30170741)

摘　　要：对2002年7～9月在广东省阳西县发生大规模死亡的赤点石斑鱼进行病原学研究,现场调查发现养殖赤点石斑鱼平均死亡率高达80%,病鱼的体征为鱼体体表有轻度溃疡,明显的腹部膨胀.解剖发现内脏严重病变,肠坏死,有少量腹水.组织切片观察发现病鱼的心、肝、肠、脾脏中存在大量的细菌,菌体呈现弥漫分布,透亮,个体为球状或短杆状.从以上器官及血液分离到3个优势菌株,分别通过肌肉注射的方法感染健康赤点石斑鱼,筛选出其中毒力较强的1株.用法国梅里埃公司的API20E试剂盒,结合专用电脑软件进行鉴定,确定为普通变形菌(Proteus vulgaris).用该菌株配制成梯度浓度的菌悬液,再次用肌肉注射的方法对健康赤点石斑鱼进行感染试验,得到其LD50为6.7×104 cfu/ml,证实了普通变形菌对赤点石斑鱼具有强毒性,可能是引起这次大规模死亡的致病菌.Mass death （80%） of redspotted grouper Epinephelus akaara cultured in cages ocurred in Yangjiang, Guangdong province from July to Septembe. r of 2001. The diseased fishes appeared slightly ulcerate on skin and obviously bloated abdomen. The serious intestine necrosis and damage were observed. The selected tissues including heart, liver, spleen and intestine were carefully excised and fixed with 5 % formalin. Then all tissue samples were dehydrated through an ascending ethanol series, embedded in paraffin, sectioned at 5μa thickmess, and stained with Haematoxyhn. Optics microscopy of Haematoxylin - stained tissues of the diseased fishes heart, liver, kidney, spleen, and intestine revealed that a great number of bacteria with lucent, globular or globular - rod shape were scattered within the tissues of the diseased fish. Three predominate strains of bacteria were isolated from the heart, liver, spleen, intestine and blood in the diseased fish. The electronic microscopy showed that these bacteria appear to be short rod with polar flagellum and have transverse binary fission mode. According to the artificial infection we found that all these three strains have different effects of pathogenicity on cultured redspotted grouper. We screened out the higher pathogenicity one and then injected the health fishes by intramuscular injection. The results appeared similar characters to natural diseased ones. This bacterium has been identified as Proteus vulgaris through physio- biochemical tests by APL20E kit. The artificial infection showed that the 50% lethal dose （LD50） of P. vulgaris in E. akaara is as high as 6.7 × 10^4/ ml. It proves that P. vulgaris might be a kind of pathogen in redspotted grouper.

关 键 词：赤点石斑鱼 普通变形菌 半致死浓度 

分 类 号：S965.334[农业科学—水产养殖]