In this study, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoribulokinase (PrkA) were overexpressed individually and in combination in Escherichia coli under different fermentation conditions. While wild-type E. coli produced 0.731 mol of CO2 per consumption of one mole of arabinose, engineered E. coli JB, containing both heterologous Rubisco and PrkA, produced only 0.621 mol of CO2 per consumption of one mole of arabinose. This represents a 15% reduction in CO2 emission and achieves 38% of theoretical CO2 reduction. The CO2 fixation rate of Rubisco-based engineered E. coli JB is 67 mg-CO2·mole-arabinose(-1) L(-1) h(-1), which is comparable to the performance of microalgae and cyanobacteria. It has been found that overexpressing Rubisco dramatically elevates the bacteria growth and sugar consumptions in the presence of oxygen and L-arabinose. It has been also found that overexpressing PrkA could demolish the balance of ATP regeneration, yet can be recovered simply by controlling the pH at 7.0±0.1.
Keywords: CO(2); Calvin cycle; Escherichia coli; Rubisco.
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