Valorization of Biodiesel Waste, Glycerine Pitch as a Substrate for Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) Biosynthesis.

Studies that focus on turning biodiesel byproducts into valuable products have recently garnered increasing attention. This investigation highlights the utilization of waste substrates for a circular economy approach using glycerine pitch as the main carbon source to produce biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [(P(3HB-co-3HV)] by Cupriavidus malaysiensis USMAA1020. The primary use of glycerine pitch, along with several parameters that may affect the growth and biosynthesis of copolymers, are investigated. The utilization of glycerine pitch along with 1-pentanol and oleic acid has the most effective effect on bacterial growth and copolymer accumulation. Response surface methodology (RSM) was used to optimize these variables. The polyhydroxyalkanoate (PHA) content increased up to 77.7 wt% from 68.9 wt%, with residual dry cell weight (RDCW) of 6.5 g/L from 4.5 g/L. The optimal conditions for producing various compositions of the 3HVs were also determined. The three selected copolymer compositions were P(3HB-co-4%3HV), P(3HB-co-11%3HV), and P(3HB-co-18%3HV). Moreover, varying the copolymer compositions produced distinct polymer characteristics. According to this study, P(3HB-co-3HV) with variable properties can be produced for a range of applications using glycerine pitch as a potential primary carbon source. In addition to reducing the cost of production, this would enhance efficient waste management.