Engineering of Ralstonia eutropha for the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from glucose

Production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with Ralstonia eutropha relies on the addition of propionate during fermentation, and propionate consumption is one of the major factors affecting the cost of PHBV production. In this study, 7 strains were obtained by genetic manipulating the methylcitric acid cycle and the methylmalonyl-CoA pathway in R. eutropha. Disruption of prpC1 and prpC2 genes did not affect cell growth and PHBV accumulation. All 7 strains were able to accumulation high amounts of PHBVs with 3HV fractions of 0.41-29.1 mol% during cultivation in flasks. Fermentation in 7.5-L fermenter showed that genetically engineered Rem-8 was able to yield biomass of 132.8 CDWg/L, of which 68.6% were PHBV with 3HV fraction of 26.0 mol% in the biopolymer, indicating promising potentials of commercialization in the future.