PHYLOGENETIC CHARACTERIZATION OF NOSTOC LINCKIA AND NOSTOC PUNCTIFORME (CYANOPROKARYOTA) BASED ON cpcB-cpcA GENE SEQUENCES

(Balik Dzhambazov). ABSTRACT. Traditionally, the taxonomy of Nostoc species has been based on morphological and physiological observations. The extreme morphological flexibility of Nostoc species, which is influenced by the life cycle stage and environmental conditions, makes identification and taxonomy based on morphology alone problematic. This is also a reason for the unresolved taxonomic positions and relationships between the genera Anabaena–Aphanizomenon as well as between Anabaena–Nostoc. Therefore, supplementary genetic information should be incorporated to give a polyphasic classification system for the order Nostocales. In light of this, we here present the first molecular and phylogenetic characterization of two species of the genus Nostoc- Nostoc linckia and Nostoc punctiforme based on the cpcB-IGS-cpcA locus of the phycocyanin operon. The phylogenetic position of these two species within order Nostocales as well as within division Cyanoprokaryota has been determined. Our results indicate that genus Nostoc is heterogeneous. Analysis of the IGS region between cpcB and cpcA showed tha