Properties of Mutants of Synechocystis sp Strain PCC 6803 Lacking Inorganic Carbon Sequestration Systems

A mutant (5) of Synechocystis sp. strain PCC 6803 constructed by inactivating five inorganic carbon sequestration systems did not take up CO2 or HCO3 and was unable to grow in air with or without glucose. The 4 mutant in which BicA is the only active inorganic carbon sequestration system showed low activity of HCO3 uptake and grew under these conditions but more slowly than the wild-type strain. The 5 mutant required 1.7 CO2 to attain half the maximal growth rate. Electron transport activity of the mutants was strongly inhibited under high light intensities, with the 5 mutant more susceptible to high light than the 4 mutant. The results implicated the significance of carbon sequestration in dissipating excess light energy.