Working CA roles on R. eutropha CO
metabolism. Schematic depiction of the role of CAs in R. eutropha metabolism. Based on experiments performed in this study, the role of Caa in R. eutropha is to convert the diffused CO2 inside the periplasm into bicarbonate to supply cellular metabolism. Can, and the less well understood Cag, would also be responsible for the supplementation of CO2 to RuBisCO. Can2, could play a role on the pH maintenance in the cell (see Additional file 1: Figure S3 which shows growth of R. eutropha H16 and Re2427 with different initial pH values). CBB cycle = Calvin-Benson-Bassham Cycle; RuBisCO = Ribulose-1,5-bisphosphate carboxylase oxygenase.