| 摘要: |
| 为探明舟山海域网箱养殖小黄鱼(Larimichthys polyactis)暴发的以体表溃疡、眼球溃烂、内脏出现白色结节为主要症状的疾病病因, 对患病小黄鱼体表溃疡处和结节病灶处采集组织样本, 在血琼脂平板上划线培养, 通过分离、纯化到同一优势菌株ZHNK2101。经形态学观察、生理生化鉴定、16S rRNA基因片段扩增及序列比对,确定该菌株为鰤鱼诺卡氏菌(Nocardia seriolae)。药敏试验结果显示, 菌株ZHNK2101对哌拉西林、头孢曲松、丁胺卡那、庆大霉素等16种抗生素敏感。回归感染试验表明, 该菌株可以感染小黄鱼并引起和自然感染相同的症状, 半致死浓度LD50为7.28×104 CFU/尾。另外,该病株会引起小黄鱼鳃、肝、肾和脾脏发生病理变化, 主要表现为鳃丝紊乱,肝脏、肾脏、脾脏组织细胞纤维化形成病理性结节。试验首次报道了小黄鱼感染鰤鱼诺卡氏菌的病例, 并从理化特性、药敏试验、回归感染及组织病理变化等方面对该菌株的特性进行了初步研究, 为小黄鱼养殖过程中由鰤鱼诺卡氏菌引起的内脏白点病的早期预防和治疗提供基础数据。 |
| 关键词: 小黄鱼(Larimichthys polyactis) 鰤鱼诺卡氏菌(Nocardia seriolae) 药敏试验 回归感染 组织学病理 |
| DOI：10.11693/hyhz20221100306 |
| 分类号:S942; Q955; S917.1 |
| 基金项目:浙江省重点研发项目, 2020C02015号; 舟山市公益类科技项目, 2022C31055号; 浙江省海洋水产研究所科技计划项目, HYS-ZY-202103号。 |
附件 |
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| ISOLATION AND IDENTIFICATION OF NOCARDIA SERIOLAE IN LARIMICHTHYS POLYACTIS |
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WU Di1,2, RUAN Ze-Chao2, WANG Yue-Bin2, ZHANG Ding-Yuan2, ZHANG Yan2, XU Wen-Jun2, CHAI Xue-Jun2
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1.Fisheries College of Zhejiang Ocean University, Zhoushan 316022, China;2.Zhejiang Key Laboratory of Marine Aquaculture, Zhejiang Institute of Marine Fisheries, Zhoushan 316021, China
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| Abstract: |
| To obtain the pathogen causing symptoms of body surface ulceration, eyeball ulceration, and visceral white nodules in cage cultured small yellow croakers Larimichthys polyactis in Zhoushan, Zhejiang, a dominant strain named ZHNK2101 was isolated from the body surface ulcerations and nodule lesions in different tissues of infected L. polyactis by plate streaking cultivation on blood agar culture medium. The isolated strain was identified as Nocardia seriolae by morphological observation, physiological and biochemical identification, amplification of 16S rRNA gene fragment, and sequence alignment. Our drug sensitivity test showed that strain was sensitive to 16 antibiotics including piperacillin, ceftriaxone sodium, amikacin, gentamicin etc. The results of regression infection test showed that the strain could infect healthy L. polyactis and cause the same symptoms as natural infection. The half-lethal dose (LD50) of the strain to L. polyactis was 7.28×104 CFU/fish. The strain could cause pathological changes in gill, liver, kidney, and spleen of L. polyactis. The main symptoms included gill filament disorder and nodules formed by cellular fibrosis in liver, kidney, and spleen tissues. We proved for the first time that N. seriolae could infect L. polyactis via drug sensitivity test, regression infection, and histological study. This research provided basic data and theoretical support for the prevention and treatment of white-spot disease caused by N. seriolae in L. polyactis. |
| Key words: Larimichthys polyactis Nocardia seriolae drug sensitivity recurrent infection histopathology |
