Polyhydroxyalkanoate (PHA) is the marine biodegradable polymer synthesized by microorganisms and can serve as a sustainable alternative to conventional plastics. Lignocellulosic biomass, an abundant, low-cost, and renewable resource, is a promising feedstock to mitigate the cost challenges associated with PHA production. In this study,
Cupriavidus necator RXI22, a recombinant microbial host previously developed [1] and capable of synthesizing poly(3-hydroxybutyrate) (PHB) from glucose and xylose, was used for PHB production from real lignocellulosic biomass hydrolysates [1]. RXI22 produced 10.7 g/L of PHB from a synthetic mixed sugar medium containing 15 g/L glucose and 15 g/L xylose, achieving a yield of 0.43 g PHB/g mixed sugars. However, when utilizing the actual lignocellulosic biomass hydrolysate as a carbon source, PHB production decreased to 5.8 g/L, with a yield of 0.31 g PHB/g sugar in hydrolysate. These reduction of 46% in PHB titer and 29% in yield were attributed to the presence of fermentation-inhibitory compounds such as acetic acid, furfural, hydroxymethylfurfural, and phenolics in the hydrolysate. To identify the major inhibitory compounds, growth and PHB production were analyzed in response to varying concentrations of these inhibitors. The effects on cell growth rate, final cell density, and carbon source consumption were evaluated in cultures supplemented with either glucose or xylose as the carbon source. Efforts to restore the strain’s performance include optimizing trace element supplementation in the medium.
[1] S. J. Lee et al., "Engineering xylose utilization in Cupriavidus necator for enhanced poly (3-hydroxybutyrate) production from mixed sugars", Bioresource Technol, vol. 418, p. 131996, 2025.
