Genetic variability of Brazilian strains of the Microcystis aeruginosa complex (Cyanobacteria/Cyanophyceae) using the phycocyanin intergenic spacer and flanking regions (cpcBA)

Brazilian strains of Microcystis aeruginosa (Kutz.) Kutz. collected from fo ur locations was examined and compared with several reference strains of M. aeruginosa, M. viridis (A. Br.) Lemm. and M. wesenbergii (Kom.) Kom. in Ko ndr. Brazilian strains were classified by morphological features and by com parison of the nucleotide sequences of the cpcBA intergenic spacer and flan king regions. Our results indicate that Brazilian strains classified as M. aeruginosa are phylogenetically diverse compared with reference strains of M. aeruginosa and that the current taxonomy underestimates genetic diversit y within M. aeruginosa. The data also demonstrate that morphological criter ia alone are inadequate to characterize Microcystis species. Although colon ial characters were shown to vary considerably in culture, some genetic lin eages demonstrated consistent cellular diameter ranges, indicating that cel l size has value as a taxonomic character. The detection of six M. aerugino sa genotypes in a single water body indicates that morphological approaches can also seriously underestimate the diversity of Microcystis bloom popula tions.