Molecular and phylogenetic characterization of two Nostoc strains isolated from Alagol and Ajigol soils (Golestan Province), Iran

Accurate identification and phylogenetic characterization of cyanobacterial strains are essential for understanding their diversity and ecological roles. In this study, Nostoc strains isolated from lake-adjacent soils of Alagol and Ajigol (Golestan province) were analyzed by amplifying functional, structural, and palindromic genes. Considering the content of this article, it is important to acknowledge the problems and inefficiencies of relying solely on morphological traits for the accurate identification of cyanobacteria. Morphological features alone often fail to distinguish closely related strains due to their variability and overlap. Therefore, new molecular techniques and polyphasic studies are justified to achieve more reliable identification. The sampling results revealed two strains belonging to the Nostocaceae family. The two strains were designated as Nostoc sp. ۱۹۸۱ and Nostoc sp. ۱۹۸۲. The phylogenetic tree constructed using the ۱۶S rRNA gene correlated with the morphological characteristics of the studied strains, placing both in a separate clade within Nostocaceae with strong bootstrap support of ۸۳.۲%. Comparative analysis of the ITS regions revealed differences in length and in the secondary structure of the D۱-D۱ and BOX B helices compared to other strains. Amplification of palindromic sequences also distinguished the two strains. Phylogenetic analysis using the rpoC۱ gene demonstrated its suitability as a marker for discriminating closely related strains. This study combines fingerprinting techniques and gene analysis to effectively differentiate closely related Nostoc strains, providing new molecular and phylogenetic insights.

کلیدواژه ها:

cyanobacteria ، Molecular Phylogeny ، palindromic genes ، rpoC۱ ، Structural genes