The investigation of phycobiliproteins in isolated heterocystous cyanobacteria from western Mazandaran

Cyanobacteria are gram-negative photosynthetic organisms and one of the most successful groups of organisms this planet has ever seen. They include some of the first life forms to evolve on Earth. During their long evolutionary history, cyanobacteria have undergone functional modifications, and these are responsible for their versatile physiology and wide ecological tolerance. The ability of cyanobacteria to tolerate high temperature, UV radiation, desiccation, and water and salt stresses contributes to their competitive success in a wide range of environments. Various species of cyanobacteria utilize different combinations of chromophores and phycobiliproteins to optimize their light-harvesting capabilities for photosynthesis. Phycobilisomes serve as the primary light-harvesting antennae for photosystem II in cyanobacteria and red algae. The aim of this research was to investigate phycobiliproteins in isolated heterocystous cyanobacteria from paddy fields in western Mazandaran. After collecting soil samples, cyanobacteria cultures were cultivated on a typical BG110. In addition to purification process, there were repeated sub-culturing on the solidified and liquid medium before the strains were characterized morphologically. Results indicated that because of adaptation of strains under accessible light condition, different species of cyanobacteria employ a high diversity of phycobiliprotein to optimize their light harvesting process in photosynthesis. Moreover, significant differences in the amounts of phycocyanin, allophycocyanin, and phycoerythrin were observed in various species. Maximum level of these protein compounds belonged to MGCY372 (Plectonema boryanum).