Valorization of fatty acids-containing wastes and byproducts into short- and medium-chain length polyhydroxyalkanoates.

Olive oil distillate (OOD), biodiesel fatty acids-byproduct (FAB) and used cooking oil (UCO) were tested as inexpensive carbon sources for the production of polyhydroxyalkanoates (PHA) with different composition using twelve bacterial strains. OOD and FAB were exploited for the first time as alternative substrates for PHA production. UCO, OOD and FAB were used by Cupriavidus necator and Pseudomonas oleovorans to synthesize the homopolymer poly-3-hydroxybutyrate, while Pseudomonas resinovorans and Pseudomonas citronellolis produced mcl-PHA polymers mainly composed of hydroxyoctanoate and hydroxydecanoate monomers. The highest polymer content in the biomass was obtained for C. necator (62 wt.%) cultivated on OOD. Relatively high mcl-PHA content (28-31 wt.%) was reached by P. resinovorans cultivated in OOD. This study shows, for the first time, that OOD is a promising substrate for PHA production since it gives high polymer yields and allows for the synthesis of different polymers (scl- or mcl-PHA) by selection of the adequate strains.