Metabolic engineering of Aeromonas hydrophila 4AK4 for production of copolymers of 3-hydroxybutyrate and medium-chain-length 3-hydroxyalkanoate

► Deletion of acetic acid pathway genes pta and ackA in A. hydrophila 4AK4 improved PHBHHx production. ► Expression of PHB precursor genes phaAB and bacterial hemoglobin gene vgb produced more PHBHHx. ► Change of PHA synthase gene phaC diversified the PHA monomers.