The presence and absence of inorganic carbon concentrating systems in unicellular cyanobacteria

The response of eight species of unicellular cyanobacteria to growth under high and low CO2 regimes was measured by RuBisCO activity and the extent of inorganic carbon concentration. No significant increase in RuBisCO activity in CO2− limited batch cultures was observed. The main feature of the data presented is the absence of a bicarbonate concentrating process in the oceanic, phycoerythrin-containing species examined, this is discussed in light of bicarbonate supply in freshwater and ocean environments.