Anabolism of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Cupriavidus necator DSM 545 from Spent Coffee Grounds Oil

Oil extracted from spent coffee grounds (SCG) [yield 16.8 % (w/w)] was discovered to be a highly suitable carbon substrate for the biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] copolymers by Cupriavidus necator DSM 545 in the absence of any traditional 3HV precursors. Cells cultivated in a 3 L bioreactor (batch) reached a total biomass concentration of 8.9 g L−1 with a P(3HB-co-3HV) (6.8 mol% 3HV) content of 89.6 % (w/w). In contrast, cells grown on sunflower oil reached a total biomass concentration of 9.4 g L−1 with a P(3HB-co-3HV) (0.2 mol% 3HV) content of 88.1 % (w/w). It is proposed that the organism could synthesize 3HV monomers from succinyl CoA, an intermediate of the tricarboxylic acid (TCA) cycle, via the succinate-propionate metabolic pathway.