Sustainable polyhydroxyalkanoates production via solid-state fermentation: Influence of the operational parameters and scaling up of the process

Polyhydroxyalkanoates (PHA) are bioplastics of growing interest due to their potential use in specialized applications obtained from renewable sources as low-cost raw materials. This study shows the effects of some operational variables affecting the PHA production via solid-state fermentation (SSF) using brewer's spent grain (BSG) and Burkholderia cepacia at lab-scale (0.5 L) and a first assessment of the process at higher scales. Temperature, pH, moisture content (MC), and sugar beet molasses (SBM) addition significantly affected the PHA production performance. From the lab-scale evaluated scenarios, the highest PHA production was 13.1 mg per gram of dry BSG when adding 30% SBM, at 70% MC, 30 °C and pH 5.5. PHA production was also tested at 3 L and 5 L using not-isolated and near-adiabatic bioreactors, respectively. At those scales, the maximum production was 9.5 mg per gram of dry BSG (0.13 g per kg per h), showing promising results towards future developments of SSF for PHA production.