Strain variation and geographic endemism in Streptococcus iniae

H. Kvitt, A. Colorni

Research output: Contribution to journalArticlepeer-review


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 biochemical profile. 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 had been 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 into only 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 to 2001) 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 high degrees 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 years was 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 and geographic endemism was established.

Original languageEnglish
Pages (from-to)67-73
Number of pages7
JournalDiseases of Aquatic Organisms
Issue number1-2
StatePublished - 21 Oct 2004
Externally publishedYes


  • AFLP
  • Endemism
  • Epidemiology
  • Identification 16S rDNA
  • RAPD
  • Strain variation
  • Streptococcus

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science


Dive into the research topics of 'Strain variation and geographic endemism in Streptococcus iniae'. Together they form a unique fingerprint.

Cite this