牙鲆迟钝爱德华氏菌的分离及其鉴定

Isolation and Identification of Edwardsiella tarda from Paralichthys Olivaceus

从患腹水病牙鲆体内分离致病菌,通过生理生化鉴定方法对该菌进行了鉴定;根据GenBank上报道的迟钝爱德华氏菌标准株(ATCC15947)的16S rDNA序列以及致病性迟钝爱德华氏菌所含有的菌毛亚基(Fi mA)基因(AB100170)的核苷酸序列设计了2对引物,对所分离到的6株疑似菌进行PCR扩增,均能够扩增出目的条带,基因片段大小分别为1 399,540 bp.序列分析表明,扩增得到的基因与其参考菌株序列高度同源,同源性分别为98.86%,100%.分子生物学鉴定结果与常规细菌鉴定方法所得结果一致,证明该菌为迟钝爱德华氏菌.将该菌肌肉注射鲫鱼,发病症状与自然死亡的症状相似,并从患病鲫鱼体内分离到该菌,说明所分离的迟钝爱德华氏菌是患病牙鲆的原发病原菌.

Pathogenic bacteria,which are isolated from Paralichthys Olivaceus suffering from ascites,are identified through physiological and biochemical methods.According to the sequences of 16S rDNA which Genbank reported from Edwardsiella tarda standard strain（ATCC15947）,as well as nucleotide sequences of pathogenic Edwardesiella tarda which contains fimbriae subunit（FimA） gene（AB100170）,two pairs of primers are designed.Then the 6 strains isolated from the suspected bacteria are amplified by PCR,and the two gene fragments needed which are sizes of 1 399,540 bp can be amplified.Sequence analysis show that the gene which is amplified has a high degree of homology with reference strain sequence homology of 98.86 % and 100 % respectively.The results of molecular identification,as well as the traditional method,prove that a type of bacteria for the Edwardsiella tarda.After intramuscular injection of the bacteria into crucian carp,the symptoms are similar to the natural death.Then Edwardsiella tarda is isolated from diseased carp in vivo,indicating it is a kind of primary pathogens which cause diseases.