Abstract
Cyanobacteria contain the carboxysome, which functions as an element of the inorganic-carbon concentrating mechanism (CCM). It has been reported that carboxysome-mutant requires High CO2. In this study, we investigated whether the increased exogenous Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) may cause the higher photosynthetic affinity for dissolved inorganic carbon (DIC) in High CO2 requiring mutant.
Carboxysomeless-mutant (CL) was selected as High CO2requiring mutant. CL has three features as follows: the requisite of High CO2, the low photosynthetic affinities for DIC, the growth inhibition under 0.5% CO2. In order to increase the exogenous RuBisCO in CL, 6803psbAII promoter and Chromatium vinosum RuBisCO were selected for constructing the expression vector. In CL transformed expression vector (CL-AX), RuBisCO activity and photosynthetic rate increased about 5 times and 2.5 times respectively. In addition, the recovery of growth inhibition under 0.5% CO2 was observed in CL-AX.
