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从广东省某市池塘采集商品规格(体重2 0～2 5kg)的草鱼(Ctenoharyngodonidellus),利用加有头孢哌酮的麦康凯琼脂培养基,对其肠道中细菌进行选择性分离与鉴定。结果显示,12尾草鱼的肠道中,5尾可分离到具有以下特征的细菌:两端生鞭毛,菌体弯曲似海鸥状,革兰氏染色阴性,过氧化氢酶、氧化酶、尿酶和精氨酸双水解酶阳性,还原硝酸盐,不发酵、氧化或同化葡萄糖、甘露醇等15种常见的糖醇类,细菌形态、生化特性与报道的香港海鸥型菌相似,阳性率为41 7%。但在肌肉中未分离到此菌。进行分离细菌的16SrRNA基因序列分析,与GenBank中登录的4株香港海鸥型菌序列的同源性为99 7%～99 9%。由菌的培养特征、形态特点、理化特性、16SrRNA基因序列分析等多元鉴定的结果表明,从草鱼肠道中选择分离的细菌为香港海鸥型菌。药敏实验结果表明,所分离菌株对奥格门丁和亚胺培南的敏感性与报道的香港海鸥型菌有一定区别。
Grass carp (Ctenoharyngodonidellus) of commercial specifications (body weight 20 ~ 25kg) was collected from a pond in a certain city of Guangdong Province. The bacteria in the intestinal tract were selectively separated and identified by using MacConkey Agar with cefoperazone. The results showed that among the 12 grass carp intestinal bacteria, 5 were isolated from bacteria with the following characteristics: flagella at both ends, cells bent like sea-gull, Gram-negative, catalase, oxidase, urease and Arginine double hydrolase positive, nitrate reduction, no fermentation, oxidation or assimilation of glucose, mannitol and other 15 kinds of common sugar alcohols, the morphology and biochemical characteristics of the bacterium were similar to those reported in Hong Kong, the positive rate was 41 7 %. However, this strain was not isolated in muscle. The 16S rRNA gene sequence analysis of isolated bacteria showed 99.7% -99 9% homology with the four strains of seagull in Hong Kong registered in GenBank. The results of multiplex identification of bacterial culture, morphological characteristics, physical and chemical properties, 16S rRNA gene sequence analysis showed that the bacteria isolated from grass carp intestine were Hong Kong seagull-shaped bacteria. The results of drug susceptibility test showed that the sensitivity of the isolated strains to Ogmentin and imipenem is different from that reported in Hong Kong.