Characterization of Nodularia strains, cyanobacteria from brackish waters,by genotypic and phenotypic methods

An investigation was undertaken of the genetic diversity of Nodularia strai ns from the Baltic Sea and from Australian waters, together with the propos ed type strain of Nodularia spumigena. The Nodularia strains were character ized by using a polyphasic approach, including RFLP of PCR-amplified 16S rR NA genes, 16S rRNA gene sequencing, Southern blotting of total DNA, repetit ive extragenic palindromic- and enterobacterial repetitive intergenic conse nsus-PCR, ribotyping and phenotypic tests. With genotypic methods, the Nodu laria strains were grouped into two clusters. The genetic groupings were su pported by one phenotypic property: the ability to produce nodularin. In co ntrast, the cell sizes of the strains were not different in the two genetic clusters. 16S rRNA gene sequences indicated that all the Nodularia strains were closely related, despite their different origins. According to this s tudy, two genotypes of Nodularia exist in the Baltic Sea. On the basis of t he taxonomic definitions of Komarek et al (Algol Stud 68, 1-25, 1993), the non-toxic type without gas vesicles fits the description of Nodularia sphae rocarpa, whereas the toxic type with gas vesicles resembles the species N. spumigena and Nodularia baltica.