Abstract
Blue green algae (Cyanobacteria) constitute the largest, most diverse and most widely distributed group of photosynthetic prokaryotes. These are known to be primary colonizers of inhospitable ecosystems in which they colonizeed almost all kinds of aquatic ecosystems. Salt tolerance is a good taxonomic character too because of their diverse morphological organization and different biochemical machineries. Four species of cyanobacteria, namely Oscillatoria tenue, Lyngbya estruarii, Scytonema major and Calothrix juliana were collected from the salt pans of Huma and cultured in medium containing varying concentrations from 0 to 25 ppt of NaCl for 20 days to asses the tolerance level of them. The growth and various macromolecular contents were determined along with the pigments on 20th day of culture. These organisms are able to tolerate the salt concentration of 5 ppt to 15 ppt.