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

Abstract

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.