Sustainable production of bioplastics from various lipid-rich oil wastes using selected pseudomonas strains

Bioplastics, also known as polyhydroxyalkanoates (PHAs), are produced by bacteria through aerobic processes using a variety of carbon sources, showing significant potential as a polymer. Despite efforts to produce cost-effective processes, the production of PHA remains expensive, posing challenges in its utilization as a cost-effective material for products. This study aims to demonstrate the potential of these microorganisms as a sustainable solution for producing bioplastics from renewable sources. The suitability of two selected Pseudomonas oleovorans (DSMZ1045 and ATCC29347) was investigated to accumulate bioplastic polyhydroxyalkanoates (PHAs) from lipid-rich wastes: Glycerol, fats, oils, and greases (FOGs), soybean oil (SO), and palm oil (PO) were used as carbon sources. Under the conditions of 180 rpm and temperature of 30℃ for 48 hours, using 2% (v/w) of each oil. The accumulated PHA was extracted using sodium hydroxide and enzyme-hydrogen peroxide-based methods. The polymers were qualitatively analysed using Fourier transforms infrared (FTIR) and Scanning electron microscopy (SEM). FTIR and SEM analyses revealed that the produced bioplastic polymers are MCL-PHAs types. However, the findings showed that these lipid-rich wastes are efficient carbon feedstocks used in producing MCL-PHAs by the selected Pseudomonas strains. The yield accumulated by P. oleovorans DSMZ1045 from these waste resources was 43wt%, 39%wt, 34%wt, and 32%wt of dry cell weight, while P. oleovorans ATCC29347 was 38%, 37%, 34%, and 33% of cell dry weight, respectively, suggesting the potential for an effective solution for producing bioplastics. The results indicated substantial improvements in PHA accumulation for both strains when pretreatment methods (lipase, microwave, and ultrasound-assisted) were employed. % PHA yield between pretreatment and non-pretreatment conditions with DSMZ1045 and ATCC29347 showing enhancement of 46.88%, 41.18%, 41.03%, and 23.26% of cell dry weight and 40.63%, 38.46%, 26.47%, and 18.60% of cell dry weight, respectively. Glycerol and FOG gave a higher PHA accumulation than the other carbon sources. More polymer yields were achieved using both oil samples from P. oleovorans DSMZ1045 compared to Pseudomonas oleovorans ATCC29347. This research underscores the viability of P. oleovorans DSMZ1045 in producing bioplastics from waste oils, especially those derived from fats, oils, and grease (FOG)