Strain variation and geographic endemism in Streptococcus iniae

Diseases of Aquatic Organisms

H. Kvitt¹  A. Colorni¹ 

关键词: Streptococcus;    Strain variation;    Identification;    16S rDNA;    RAPD;    AFLP;    Endemism;    Epidemiology;   

DOI  :  10.3354/dao061067

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Twenty-six Israeli isolates of Streptococcus iniae from both marine and fresh/brackish water sources were compared with each other and with 9 foreign isolates. All the isolates were tentatively identified according to their biochemicalprofile. Direct sequencing of approximately 600 bp PCR products of the 16S rDNA confirmed their identification as S. iniae at the molecular level and revealed a new (one-nucleotide) variant among Israeli isolates, in addition to 2 variants that hadbeen previously reported. Strain variation was further examined by subjecting the isolates to randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analyses. The RAPD method allowed separation of the isolates intoonly 2 groups, one including 5 Israeli fresh/brackish water isolates and one including all the other isolates. The AFLP method grouped the Israeli marine isolates into one homogeneous cluster, although they had been obtained in different years (1995 to2001) from different species of fish, and from wild (Red Sea) as well as cultured (both Mediterranean and Red Sea) sources. The Israeli fresh/brackish water isolates and foreign isolates separated into distinct entities that clustered at generally highdegrees of similarity. The distance between the clusters of the Israeli marine and fresh/brackish water isolates indicates that the S. iniae streptococcosis that has been afflicting the aquaculture industries in the 2 environments in recent yearswas caused by distinct strains. AFLP showed superior discriminative properties over RAPD in detecting intraspecific variation and proved to be an important tool for the characterization of S. iniae. A correlation between strain variation andgeographic endemism was established.

【 授权许可】

Unknown