High-efficiency transformation and gene expression in Picosynechococcus sp. PCC 7002

Cyanobacteria are promising microbial platforms for a myriad of biotechnological applications, from sustainable biomaterials to photosynthetic chemical production, but still lack the breadth of genetic tools available for more commonly engineered microbes such as Escherichia coli. This study develops genetic tools to enhance the transformation efficiency and heterologous gene expression in Picosynechococcus sp. PCC 7002, a fast-growing, halotolerant, and naturally competent strain. Integration of fluorescent reporter cassettes across the genome revealed an integration site that yields a fourfold improvement in gene expression relative to previously reported sites. Protocol optimization and engineered DNA methylation in E. coli increased transformation efficiency by over tenfold. This work provides an experimental framework for efficient genome editing and metabolic engineering in the model cyanobacterium PCC 7002.