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

• Polyhydroxyalkanoates (PHAs) were produced from fatty acids-containing substrates.
• scl- and mcl-PHA with distinct composition, molecular mass and thermal properties were obtained.
• Olive oil distillate (OOD) was tested for the first time and yielded the highest PHA production.
• Cupriavidus necator converted OOD into scl-PHA.
• Pseudomonas resinovorans converted OOD into mcl-PHA.

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.