Properties and Application of Luffa aegyptiaca and Citrullus lanatus Seed Lipases in the Degradation of Palm Oil Effluent (POE)

Enzyme pretreatment of palm oil effluent (POE), a significant environmental pollutant, offers an eco-friendly and cost-effective alternative over chemical pretreatment methods. Hence, this research explored the properties of lipases from Luffa aegyptiaca and Citrullus lanatus as well as their potential in the pretreatment of POE. Lipases were obtained on the 4th and 6th day of Luffa aegyptiaca and Citrullus lanatus seeds germination, with specific activities (SAs) of 211.81 and 170.56 U/mg, respectively. After ion exchange and gel filtration chromatography, the SAs were 546.88 and 490.55 U/mg, respectively. The enzymes were stable at a temperature and pH range of 50-80 °C and 5.0- 9.0. The pH optima of the Luffa aegyptiaca and Citrullus lanatus lipases were 7.0 and 6.0, respectively. The optimal temperatures for the Luffa aegytiaca and Citrullus lanatus lipases were 60 and 50 °C, respectively. The Michaelis constant (Km) and maximum velocity (Vmax) of 0.32 mM and 200 μmol/min were obtained for Luffa aegyptiaca lipase, whereas 0.370 mM and 197.27 μmol/min were obtained for Citrullus lanatus lipase. Metal ions (Fe2+, Ca2+, and Co2+) significantly (p<0.05) enhanced the lipase activity more than Mn2+ in a concentration-dependent manner. Pretreatment of POE with lipases enhanced the reduction of total organic carbon, biochemical oxygen demand, and total organic matter. Also, the pH and dissolved oxygen content of the effluent were increased. The properties of Luffa aegyptica and Citrullus lanatus lipases and their ability to degrade palm oil effluent make them ideal for the sustainable and successful pretreatment of POE.