Exploiting Cyanobacterial RecET Homologues to Improve Genetic Engineering Efficiency in Synechocystis sp. PCC 6803

Cyanobacteria offer a sustainable and environmentally friendly method of light-driven biosynthesis of chemicals with minimal environmental impact, making them an extremely attractive proposition in alleviating society’s dependency on fossil fuels. To fully exploit cyanobacteria as a chassis to meet society’s demands for energy and chemical production, genetic modification is a crucial step in improving productivity through the expression of heterologous and novel biosynthetic pathways. Genome mining was carried out with the aim of identifying potential recE and recT homologues to improve the efficiency of genetic manipulation. Two promising candidate homologues of recT and cas4 (recE homologue) were identified from the cyanobacterium Aphanocapsa feldmanni. Expression of these candidates increased recombination efficiency 3-fold, generating mutants with the expected genotypes and phenotypes, which were comparable to mutants created with conventional knockout protocols using suicide vectors. These results indicate that cyanobacteria possess recombination homologues that can be re-purposed to improve the efficiency of genome engineering to accelerate cyanobacteria for strain development.