Effect of limonene on the heterotrophic growth and polyhydroxybutyrate production by Cupriavidus necator H16

- Use of orange juicing waste for the production of PHB by Cupriavidus necator.
- Initial fructose concentration of 24.7 g L−1 was achieved by autohydrolysis.
- Yp/s of 0.39 gPHB g−1fru corresponding a final PHB concentration of 7.3 g L−1.
- Strong inhibitory effects of limonene were found above 1% (v/v).

The inhibitory effect of limonene on polyhydroxybutyrate (PHB) production in Cupriavidus necator H16 was studied. Firstly, results demonstrate the feasibility of using orange juicing waste (OJW) as a substrate for PHB production. An intracellular PHB content of 81.4% (w/w) was attained for a total dry matter concentration of 9.58 g L−1, when the OJW medium was used. Later, a mineral medium designed to mimic the nutrient levels found in the complex medium derived from OJW was used to study the effect of limonene on the production of PHB. Results showed a drop in specific growth rate (μ) of more than 50% when the initial limonene concentration was 2% (v/v) compared to the limonene free medium. This work highlights the importance of a limonene recovery stage prior to fermentation, to maintain levels below 1% (v/v) in the medium, adding value to the OJW and enhancing the fermentation process productivity.