Productivity increment of biodegradable and biorenewable copolymer containing 3-hydroxyvalerate monomer initiated by alcohols as precursor substrates

摘要

Background: The production cost and the material properties of polyhydroxyalkanoate (PHA), a biodegradable plastic are common issues of debate. It has become a constant challenge for researchers to find suitable and relatively cheap carbon substrates. This study has investigated the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)], using a combination of fatty acids and alcohols. The fermentation process described in this study also highlights the potential use of 1-pentanol for the generation of 3HV monomer, in contrast to odd carbon numbered volatile fatty acids, which are known to exert some levels of toxicity towards the cells. Results: Among the various mixtures of fatty acids and 3HV precursors, the mixture of 0.50 wt% C oleic acid and 0.06 wt% C 1-pentanol was found suitable for the production of this copolymer. It was found that Cupriavidus sp. USMAA2-4 could produce up to 56 wt% of P(3HB-co-3HV) with 8 mol% 3HV monomer units. The 3HV monomer composition was also successfully regulated in the range 3-66 mol% by manipulating the culture conditions. The number average molecular weight of the copolymer produced was in the range 217-351 kDa. Conclusion: The findings of this study might be used as a platform for scale-up production of 3HV copolymers with different monomer compositions using mixtures of oleic acid and alcohols, namely 1-pentanol for a sustainable production process.