Modification of carbon partitioning to enhance PHB production in Synechocystis sp. PCC6803

A Synechocystis sp. PCC6803 ADP-glucose pyrophosphorylase gene—agp gene—deletion-mutant has been obtained to modify the cellular carbon partitioning for enhancing cyanobacterial PHB production. With different carbon sources in the culture media, the rates of oxygen evolution in the mutant cells were 20–25% higher than those in the wild-type cells. No glycogen was detected in the mutant, and PHB synthesis was enhanced upon the deletion of glycogen synthesis. Under photoautotrophic condition, the mutant accumulated PHB to 14.9% of the dry cellular weight. The highest intracellular PHB content was 18.6% in the presence of acetate.