【作者】 张占会；

【导师】 张其中；

【作者基本信息】 暨南大学 ， 水生生物学， 2006， 硕士

【摘要】 近江牡蛎是我国南方最大宗的养殖贝类，主要分布于广东、广西、福建和海南等省沿海。但自1992年以来频发的大规模死亡事件严重影响了近江牡蛎养殖业的发展。死亡原因目前还不清楚，推测可能是病原微生物和高温、高盐度等环境因素造成，已报道的可疑生物病原只有类立克次体。本次研究主要从微生物病原入手，通过人工感染实验筛查三类主要病原微生物(细菌、病毒和类立克次体)对近江牡蛎的致死情况，从而明确近江牡蛎的致病微生物。 从疫区患病近江牡蛎提取类立克次体悬液、病毒悬液(患病牡蛎组织匀浆后微孔滤膜(0.2μm)滤过液)和分离纯化出11株细菌，对健康近江牡蛎进行人工注射感染实验，结果显示病毒和类立克次体悬液注射组死亡率与对照组无显著差异，11株细菌中有四株细菌注射组死亡率显著高于对照组。 采用Biolog系统和16S rDNA比对方法对四株细菌进行了菌种鉴定，结果表明两株为溶藻弧菌(Vibrio alginolyticus)，一株为解蛋白弧菌(Vibrio proteolyticus)，一株为鲨鱼弧菌(Vibrio carcariae)。 药敏试验显示四株细菌对青霉素类药品均有抗药性，对四环素也都不敏感，而对氯霉素和诺氟沙星敏感。 组织病理观察发现：患病牡蛎主要受损器官是消化盲囊。主要表现为腺泡管内壁吸收细胞崩解脱落，管腔扩大，进而管壁解体，消化盲囊出现大面积受损。更多还原

【Abstract】 The oyster, Crassostrea ariakensis, is extensively cultivated in estuarine areas of southern China seas, especially in the Pearl River valley of Guangdong Province, and represents an important economic activity. The oyster aquaculture has grown rapidly, however, annual mass mortality (nearly 60～80%), usually from February to May and November to December of every year, has re-occurred in major reared regions since 1992. The causes of mortality outbreaks have not been understood, so it is important to reveal them for the sustainable development of this industry. Previous researches showed that microorganismal pathogens in the host were major causative agent of mass mortality in the Pacific oyster Crassostrea gigas and the eastern oyster Crassostrea virginica etc. The present study was carried out to screen and identify the pathogenic microorganisms associated with mass mortality of the oyster C. ariakensis. Challenge experiments were conducted by injection into healthy cultured oysters C. ariakensis with potential virus, RLO and 11 strains of bacteria, which were isolated from the moribund oysters during oyster mortality outbreaks occurring on rearing site. Our experimental results showed that the mortalities of the oysters caused by potential virus and RLO were not significantly different from those of the control, while the mortalities among groups injected by four strains of the bacteria were significantly higher than the control group, two strains of Vibrio alginolyticus, one strain of Vibrio proteolyticus and one strain of Vibrio carcariae, were identified by the Biolog bacteria identification system and 16S rDNA sequence comparison respectively. The mainly damaged organ of the oyster C. ariakensis was digestive gland.The absorptive cells in the wall of digestive gland tubules were broken and shed, furthermore, the tubule wall collapsed, and the digestive gland were extensively damaged. The drug sensitivity testing indicated the four strains of vibrio were resistant to penicillin G, ampicillin and Erythromycin, and sensitive towards chloramphenicol and norfloxacin.更多还原