Phenotypic variation in wild-type substrains of the model cyanobacterium Synechocystis sp. PCC 6803

Genome re-sequencing has revealed numerous genetic differences between wild-type substrains of the model cyanobacterium Synechocystis sp. PCC 6803 held in laboratories around the world. These substrains can be divided into the motile PCC-lineage and non-motile GT-lineage, and frequently display unique genetic mutations that result in residue changes in proteins associated with environmental sensing, gene regulation, cellular transport and photosynthesis. However, despite these findings, phenotypic variation between wild-type substrains does not appear to have been widely reported. In this study, we compared the growth and physiology of three wild-type substrains of Synechocystis sp. PCC 6803, the GT-Kazusa substrain (the source of the original genome sequence for this cyanobacterium), the widely studied PCC-Moscow substrain, and the GT-O1 substrain, in use in our laboratory. We found similarity between all three substrains in terms of growth rate, oxygen evolution and total chlorophyll levels. Although differences in cell size, whole-cell absorption and 77 K fluorescence were observed, the wild-type substrains analysed here are comparable under standard laboratory conditions.