Application of Pyrosequencing Method for Investigating the Diversity of Synechococcus Subcluster 5.1 in Open Ocean

Synechococcus are distributed throughout the world's oceans and are composed of diverse genetic lineages. However, as they are much less abundant than Prochlorococcus in oligotrophic open oceans, their in- depth genetic diversity cannot be investigated using commonly used primers targeting both Prochlorococcus and Synechococcus. Thus, in this study, we designed a primer specific to the 16S-23S rRNA internal transcribed spacer (ITS) of the Synechococcus subcluster 5.1. Using the primer, we could selectively amplify Synechococcus sequences in oligotrophic seawater samples. Further, we showed that a barcoded amplicon pyrosequencing method could be applicable to investigate Synechococcus diversity using sequences retrieved in GenBank and obtained from environmental samples. Allowing sequence analyses of a large number of samples, this high-throughput method would be useful to study global biodiversity and biogeographic patterns of Synechococcus in marine environments.