Molecular taxonomic evaluation of Anabaena and Nostoc strains from the Mosonmagyaróvár Algal Culture Collection.

The taxonomy of genera Anabaena and Nostoc is very controversial. They are typically paraphyletic within phylogenetic trees and show similar morphological characters. The present study aimed to determine the taxonomic relationships among Anabaena and Nostoc strains of the Mosonmagyaróvár Algal Culture Collection (MACC) using 16S rRNA and rbcLX gene sequences. We concluded on the basis of the number of unsuccessful amplifications that more of the examined MACC Nostoc cultures are axenic than the Anabaena cultures. In agreement with previous studies we noticed that the applied phylogenetic algorithms gave congruent results in phylogenetic analyses. However, the genus Nostoc clearly was found not monophyletic in the present study and this finding differed from many of the previous studies. Molecular results contradicted the previous morphology-based classification of some MACC cyanobacteria strains, therefore polyphasic taxonomic approaches are required for the reliable identification of cyanobacterial species. Some strains seemed to be identical based on the alignment of 16S rRNA or rbcLX sequences. • Taxonomic relationships among Anabaena and Nostoc strains of the MACC were determined using 16S rRNA and rbcLX gene sequences. • More Nostoc cultures were found to be axenic than Anabaena cultures. • The genus Nostoc clearly was not found monophyletic in this study. • Molecular results contradicted the previous morphology-based classification of some MACC cyanobacteria strains. • Some strains seemed to be identical based on the alignment of 16S rRNA or rbcLX sequences. [ABSTRACT FROM AUTHOR]