Improvement of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) production by dual feeding with levulinic acid and sodium propionate in Cupriavidus necator.

In the context of increasing volatility of oil prices, replacement of petroleum based plastics by bioplastics is a topic of increasing interest. Poly(hydroxyalkanoate)s (PHAs) are among the most promising families in this field. Controlling composition of the polymer on the monomeric level remains a pivotal issue. This control is even more difficult to achieve when the polymer is not synthesized by chemists, but produced by nature, in this case, bacteria. In this study mechanism and role of two 3-hydroxyvalerate (3-HV) inducing substrates on the production of PHBV with high, 80%, 3-HV content were evaluated. It was found that levulinic acid contributes to biomass and bio-polymer content enhancement, whereas sodium propionate mainly contributes to 3-HV enhancement. Optimized proportions of feeding substrates at 1 g/L and 2.5 g/L, respectively for levulinic acid and sodium propionate allowed a 100% productivity enhancement, at 3.9 mg/L/hour, for the production of PHBV with 80% 3-HV.