BACKGROUND: The paper reports an investigation into the possibility of producing poly-3-hydroxybutyrate (P(3HB)) polyester using corn syrup, a relatively low cost by-product from the starch industries. The concentrations of medium components, corn syrup, dipotassium hydrogen phosphate (K2HPO4), sodium dihydrogen phosphate (NaH2PO4) and ammonium sulfate [(NH4)2SO4] were optimized using design of experiments (DOE).
RESULTS: Response surface methodology (RSM) under central composite face design (CCFD) was used to obtain the optimum values of medium components and responses in terms of biomass yield and volumetric P(3HB) productivity. The highest P(3HB) productivity and biomass yield obtained were 0.224 g L−1 h−1 and 0.57 g g−1, respectively. A limited-nitrogen concentration had a higher volumetric P(3HB) productivity (0.170 g L−1 h−1) than that of the excess nitrogen batch experiment (0.0675 g L−1 h−1). The optimum corn syrup:N:P ratio of 50:0.078:1 was based on numerical optimization of the desirability function between biomass yield and volumetric P(3HB) productivity by Cupriavidus necator DSMZ 545.
CONCLUSION: The results obtained in this study demonstrated that P(3HB) could be efficiently produced to a high concentration with high productivity by applying nitrogen limitation in a defined medium, indicating this agricultural by-product to be a suitable nutrient source in further studies to develop biomaterials through biotechnology. Copyright © 2010 Society of Chemical Industry