Antibiotics-free stable polyhydroxyalkanoate (PHA) production from carbon dioxide by recombinant cyanobacteria

► An antibiotics-free plasmid expression system for cyanobacteria was developed. ► The selection pressure is the complementation of recA null mutation by Escherichia coli recA. ► Fixation and conversion of CO2 into useful biomaterials by transgenic cyanobacteria. ► PHA (biodegradable plastic) was produced by transgenic cyanobacteria. ► PHA productivity was up to 52% of cell dry weight.