Isolation of cyanophages from aquatic environments

Cyanophages are a group of viruses which specifically infect cyanobacteria. The cyanobacteria are predominantly aquatic phototrophic bacteria and the two dominant genera Synechococcus and Prochlorococcus contribute significantly to primary production in the oceans. Cyanophages that infect marine cyanobacteria were first isolated in the early 1990s and it is now known that by lysing their host cells they play an important role in the microbial loop and alter biogeochemical cycles. They are also thought to influence the community structure and evolution of the cyanobacteria that they infect. Most recently cyanophages have been shown to carry host photosynthetic genes. It was only by the isolation and purification of cyanophage isolates have these important functions become known. Although this chapter illustrates cyanophage isolation with Synechococcus, the same techniques will apply to isolation of phage from other cyanobacteria. With the continued isolation of cyanophages a greater understanding of their biological importance will be gained.