Natural community structure of cyanobacteria in the South China Sea as revealed by rpoC1 gene sequence analysis

Aims: To examine the community structure of cyanobacterial populations of the South China Sea on the surface and at depth of 80 m. Methods and Results: Direct PCR amplification of RNA polymerase (rpoCl) genes from environmental DNAs extracted from seawater, and cloning of the fragments and sequence analysis were used. A great diversity of Prochlorococcus and Synechococcus were detected at the investigation site. Genetically related Prochlorococcus were found in both layers while Synechococcus were found only on the surface. Prochlorococcus were clustered with the known high-light adapted II genotypes, and further divided into seven groups. Synechococcus could be divided into two groups, and the second group could be further subdivided into several clades. Conclusion: The dominant genotype of Prochlorococcus was high-light adapted II genotype, and Synechococcus were distributed basically on the surface. Significance and Impact of the Study: This is the first report about the cyanobacterial community structure in the South China Sea, and an important supplement to the current understanding of the relationship between genetic and ecological diversity and environments.