Assessment of the genetic diversity of halotolerant coccoid cyanobacteria using amplified 16S rDNA restriction analysis

Genetic diversity of 12 strains of coccoid cyanobacteria of different hyper saline origins has been studied by amplified 16S rDNA restriction analysis and compared with morphological characters. Cluster analysis was performed on amplified 16S rDNA restriction analysis profiles of those strains along with profiles obtained from sequence data of unicellular halotolerant cyano bacteria belonging to the recently described Halothece cluster. By using th is approach, all new strains could be assigned to the Halothece cluster, co nfirming that unicellular extremely halotolerant cyanobacteria form a monop hyletic group among cyanobacteria. New branches inside the Halothece cluste r were found and groups of very tightly related strains resulted. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Sci ence B.V. All rights reserved.