Biosynthesis and Compositional Regulation of Poly[(3‐hydroxybutyrate)‐co‐(3‐hydroxyhexanoate)] in Recombinant Ralstonia eutropha Expressing Mutated Polyhydroxyalkanoate Synthase Genes

Abstract

Summary: A new strategy for bacterial polyhydroxyalkanoate (PHA) production by recombinant Ralstonia eutropha PHB⁻4 harboring mutated PHA synthase genes (phaC_Ac) from Aeromona caviae was investigated. The strain harboring wild‐type phaC_Ac gene produced a PHA copolymer consisting of (R)‐3‐hydroxybutyrate and (R)‐3‐hydroxyhexanoate [P(3HB‐co‐3HHx)] with 3.5 mol‐% of 3HHx fraction from soybean oil. When the mutants of phaC_Ac gene were applied to this production system, 3HHx fraction in copolymers was varied in the range of 0–5.1 mol‐%. Thus, the regulation of PHA copolymer compositions has been achieved by the use of mutated PHA synthase genes. Relationship between PHA synthase activity and 3HHx fraction in P(3HB‐co‐3HHx).