Protein fingerprinting may serve as a complementary tool for the phylogenetic classification of heterocystous (Nostoc, Anabaena, Cylindrospermum, Aulosira and Tolypothrix) Cyanobacteria

A combination of morphology, SDS-PAGE, 16S rRNA gene and the fuzzy approach has been used for the first time to attest the phylogenetic affiliation of the cyanobacterial species such as Nostoc, Anabaena, Cylindrospermum, Tolypothrix and Aulosira. The idea was to ascertain as how far SDS-PAGE analysis and morphological taxonomy work coherently and serve as a reliable tool, compatible with 16S rRNA gene based classification of cyanobacteria. Intermingling of Nostoc and Anabaena species in SDS-PAGE and 16S rRNA gene indicates that the two taxa are not clearly separated at the genetic level and may be polyphyletic in origin. In contrast to this, clustering of Tolypothrix and Aulosira species in the same clade attests the taxonomic coherence of these species. However, Cylindrospermum showed greater phylogenetic relatedness with Anabaena strain in all phylogenetic analyses. Despite a few minor incongruities, protein fingerprint depicted greater similarity with 16S rRNA gene as compared to morphological taxonomy. Thus protein fingerprinting developed using fuzzy approach appears to be more compatible with 16S rRNA gene analysis than morphological taxonomy in discriminating cyanobacteria up to the species level.