RNA-seq analysis of Synechocystis sp. PCC 6803 substrains and their derivatives.

Synechocystis sp. PCC 6803 substrain PCC-P formed laboratorial bloom with viscous sulfated exopolysaccharide accumulation, though Synechocystis sp. PCC 6803 substrain GT-I did not show such a phenomenon. We identified the sulfated EPS and its biosynthesis genes on the mega plasmid pSYSM. We also found the regulatory genes and confirmed their transcriptional regulation of EPS biosynthesis genes by quantitative PCR. To determine what other genes are regulated by this regulatory system and whether the transcription levels of the exopolysaccharide biosynthesis genes differ between PCC-P and GT-I, we performed RNA-seq analysis on the two substrains and the deletion mutant of the regulatory genes.