Very little is known about how members of the phylum cyanobacteria affect and respond to changes in complex biological systems. To fill this knowledge-gap we selected 26 photosynthetic consortia, based on their collection site and growth condition, from a total of over 1,200 environmental samples available in the Culture Collection of Microorganisms from Extreme Environments (CCMEE) for 16S rRNA sequencing to identify common community members and potential keystone species. Results from this work will help to determine the nutritional and environmental requirements of microorganisms that can currently only be grown in co-culture and to define the molecular processes that facilitate carbon and nitrogen sequestration by these phototrophic consortia and the individual organisms that contribute to them.