Genetic engineering to improve resistance against heavy metal stress in <i>Synechocystis</i> sp. PCC 6803

Cyanobacteria, which possess photoautotrophic capacity, demonstrate excellent capabilities in water remediation. As ideal species integrating both photosynthetic carbon fixation and bioremediation functions, cyanobacteria have garnered significant attention for environmental bioremediation applications. Consequently, the selection of superior cyanobacterial strains and genetic engineering for improvement have become increasingly critical to advance practical application in ecological remediation processes. <i>Synechocystis</i> sp. PCC 6803 possesses a well-defined genetic background and a natural DNA transformation system, making it an ideal platform for gene editing and metabolic engineering. In this study, we successfully constructed transgenic <i>Synechocystis</i> sp. PCC 6803 strains expressing exogenous genes encoding MntH, HMP3, SodA, and SodC, respectively. The heavy metal resistance of transgenic strains was significantly improved. This study underscores the efficacy of exogenous functional genes in improving cyanobacterial stress resistance and offers both theoretical and technical foundations for the development of more robust cyanobacterial chassis cells.