Microorganism having multiple genes encoding PHA synthase and method for producing PHA using same

A method for producing a mixture of polyhydroxyalkanoic acid (PHA) polymers comprising hydroxyalkanoic acid monomeric units, the method comprising:

• culturing a microorganism comprising two different genes encoding two different PHA synthases that synthesize two different PHA polymers,
• wherein a first gene of the two different genes encodes a first PHA synthase that synthesizes a first PHA polymer, a PHA copolymer (A), which is derived from the genus Aeromonas, and a second gene of the two different genes encodes a second PHA synthase that synthesizes a second PHA polymer, a PHA polymer (B), that has a melting point different from a melting point of the PHA copolymer (A) by at least 10° C., such that the PHA copolymer (A) and the PHA polymer (B) are independently and simultaneously produced in a cell of the microorganism, thereby producing the mixture of the PHA copolymer (A) and the PHA polymer (B) in the cell,
• wherein the melting point of the PHA polymer (B) is higher than the melting point of the PHA copolymer (A), and the PHA polymer (B) is a polymer comprising at least 99% by mole of 3-hydroxybutyric acid as a monomeric unit,
• wherein the PHA copolymer (A) is a copolymer comprising 3-hydroxybutyric acid and 3-hydroxyhexanoic acid as monomer units,
• wherein the PHA copolymer (A) comprises at least 8% by mole of the 3-hydroxyhexanoic acid as a monomeric unit,
• wherein an amount of the PHA polymer (B) in the mixture is from 0.1 to 20 wt. % based on the total amount of the PHA copolymer (A) and the PHA polymer (B), and
• wherein the mixture of the produced PHA polymers has a plurality of endothermic peaks between 85° C. and 180° C. in a differential scanning calorimetry (DSC) curve of the mixture, and, among the endothermic peaks, an endothermic peak at a highest temperature has a calorie of 0.2 to 20 J/g.