Cyanobacteria are important players in the global carbon cycle, accounting for approximately 25% of global CO2 fixation. Their CO2-concentrating mechanisms (CCMs) are thought to play a key role in cyanobacterial calcification, but the mechanisms are not completely understood. In Synechocystis sp. strain PCC 6803, a single Ca2+/H+ exchanger (Slr1336) controls the Ca2+/H+ exchange reaction. We knocked out the exchanger and investigated the effects on cyanobacterial calcification and CCMs. Inactivation of slr1336 significantly increased the calcif...
