The toxigenic and bloom-forming cyanobacterial genus Microcystis conta
ins several ill-defined species. The 16S rDNA for two strains of toxic
M. aeruginosa were sequenced and compared to available cyanobacterial
, bacterial, and chloroplast 16S rRNA gene information. Phylogeny and
the validity of a molecular taxonomy for the genus Microcystis is pres
ented.