Characteristics of used palm olein and its bioconversion into polyhydroxybutyrate by Cupriavidus necator H16

Aims: The accumulation of synthetic plastic waste that pollutes the environment has raised awareness of the advantages of biodegradable polymers such as polyhydroxybutyrate [P(3HB)]. Nevertheless, high production costs of such environmental-friendly plastics have held back its more widespread use. One major cost component is the carbon source used in its production. Hence, this study was undertaken to evaluate used palm olein (UPO) as a potential carbon source for the production of P(3HB). Methodology and results: Both UPO and fresh palm olein (FPO) were analysed for physicochemical and proximate characteristics and thermal properties. Compared with FPO, the composition of palmitic acid (C16:0) in UPO was increased from 40.3% to 43.7%, while the composition of linoleic acid (C18:2) was reduced from 11.3% to 7.6%. The iodine value declined from 55.8 g I2/100g in fresh palm olein to 39.5 g I2/100g in UPO, this being an indication of increased saturated bonds that contribute to a high efficiency of P(3HB) synthesis. Production of P(3HB) by Cupriavidus necator H16 using UPO as the carbon source reached 83% of dry cell weight, with the highest P(3HB) content attained after 48 h. Conclusion, significance and impact study: We conclude that UPO has the potential to be used as a low cost carbon source for the efficient biosynthesis of P(3HB).