Crude glycerol as feedstock for polyhydroxyalkanoates production by mixed microbial cultures

• Crude glycerol was used as feedstock to produce biopolymers using aerobic mixed cultures.
• From the glycerol fraction of the crude PHB and GB were stored.
• A maximum PHB content of 47% cell dry cell was obtain with crude glycerol.
• Selected culture was able to achieve 53% of PHB using synthetic glycerol.

The increase in global biodiesel production makes imperative the development of sustainable processes for the use of its main by-product, crude glycerol. In this study the feasibility of polyhydroxyalkanoates (PHA) production by a mixed microbial community using crude glycerol as feedstock was investigated. The selected culture had the ability to consume both glycerol and methanol fraction present in the crude. However, glycerol seemed to be the only carbon source contributing for the two biopolymers stored: poly-3-hydroxybutyrate (PHB) and glucose biopolymer (GB). In this work the culture reached a maximum PHB content of 47% (cdw) and a productivity of 0.27 g X/L.d, with an aerobic mixed cultures and a real waste substrate with non-volatile fatty acids (VFA) organic matter. The overall PHA yield on total substrate obtained was in the middle range of those reported in literature. The fact that crude glycerol can be used to produce PHA without any pre-treatment step, makes the overall production process economically more competitive, reducing polymer final cost.

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