Because of its application potential and biodegradability, poly(3-hydroxybutyrate-co-3-hydroxyvalerate;PHBV), a member of the polyhydroxyalkanoates (PHA) biopolymer family, is one of the most extensively studied PHA. High PHBV productivity with a significant amount of hydroxyvalerate (HV) content is very appealing for commercial scale production. The goal of this study was to investigate the efficiency of various defined limitation strategies, namely nitrogen, phosphorus, and oxygen-limitation, for high yield PHBV production by Cupriavidus necator H16 with increased HV unit using waste frying vegetable oil (WFO) and propionic acid (PA) in a high cell density culture (5 L bioreactor). With optimized WFO and PA feeding, highest PHBV harvest (121.7 ± 2.59 g/L; HV 13.9 ± 0.44% (w/w)) and volumetric productivity (2.03 ± 0.04 gPHBV/L·h) were obtained in oxygen-limited operation, while highest HV content (19.8 ± 0.28 wt%) and yield coefficient (0.43 ± 0.017 gHV/gPA) were observed during phosphorus-limited cultivation. Although nitrogen limitation is widely applied in the production of PHA, nitrogen-limited cultivation had the lowest cell dry matter, PHBV production, volumetric productivity, oil-to-HB and PA-to-HV yield coefficients for the given conditions. The results of the present study demonstrate the highest PHBV yield together with the highest HV content using WFO as main carbon source and PA as the HV precursor ever reported in the literature.
Keywords: Cupriavidus necator; poly(hydroxybutyrate‐co‐hydroxyvalerate); polyhydroxyalkanoate; propionic acid; waste vegetable oil.
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate;PHBV), a member of the polyhydroxyalkanoates (PHA) biopolymer family, is one of the most extensively studied PHA due to its high application potential and biodegradability properties. High PHBV productivity with substantial amount of hydroxyvalerate (HV) content is of great interest for commercial scale PHA production to compete with conventional plastic costs.In this study, we investigated the effectiveness of different nutrient limitation strategies in optimizing the production of PHBV from waste frying vegetable oil and propionic acid. Although there are individual studies investigating the performance of operational PHBV production strategies such as nitrogen, phosphorus, or oxygen limitation, none of them have comprehensively compared the effect of different limitation strategies on PHA production parameters using waste frying vegetable oil as the main carbon source and propionic acid as the cheapest HV precursor. To our knowledge, this is the first study that evaluates the impact of these three limitation strategies on the efficient production of PHBV from waste frying oil and propionic acid in high cell density fermentations of Cupriavidus necator H16. The results demonstrate the highest PHBV yield together with the highest HV content using waste frying oil as main carbon source and propionic acid as the cheapest HV precursor ever reported in the literature. In addition, it is shown that the PHBV yield and its HV content could be intercorrelated by switching between oxygen and phosphorus-limited strategies for desired material specifications.