Fatemeh Heidari - Faculty of life sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
Hossein Riahi - Faculty of life sciences and biotechnology, ShahidbBeheshti University, Tehran, Iran
Zeynab Shariatmadari - Faculty of life sciences and biotechnology, Shahid Beheshti University, Tehran, Iran
Morteza Yusefzadi - Faculty of Basic Science, Hormozgan University, Bandar Abbas, Iran

Hot springs have been a subject of intensediscussion for biologists in the last decades.The polyphasic approach is the most progressivesystem that has been suggested for distinguishingand phylogenetically classifying cyanobacteria.In a revision of the cyanobacteria inhot springs of Iran, four hot springs of Iran wereinvestigated. We developed a combined molecularand morphological approach to identificationof cyanobacteria. In this study seventeenpopulations and ۱۳ morphological characterswere analyzed. Molecular study based on ۱۶SrRNA gene sequence does not disrupt morphologicalinformation and it confirms the separationof studied taxa according to morphologicalcharacters. Based on their growth characteristics;seven species were selected for the productionof antimicrobial agents. The results ofthis study showed that the methanol extractsexhibited high antimicrobial activity againstsome gram positive bacteria, moderate antibacterialactivity against some gram negativeorganisms and moderate antifungal activityagainst some fungi. Four species were selectedfor salinity tolerance. The results showed hightolerance of these taxa to salinity.

Cyanobacteria, Hot Spring, Morphological Diversity, ۱۶S rRNA, Polyphasic study