Massive amounts of waste oil generated by restaurants and native homes in Egypt are dumped into sewage systems, causing network damage. Utilization of waste cooking oil (WCO) in biodiesel production, can aid in solving the problem.

In the present study, a new lipase-producing bacterium (Bacillus subtilis) was isolated, identified using 16S rRNA sequence analysis, and the isolate sequence was deposited in GenBank (accession number: MN238705). The lipase coding sequence was amplified from the abovementioned strain cloned and expressed in Escherichia coli. The molecular weight of the purified enzyme tagged with glutathione-S-transferase (GST) was approximately 49 KDa on SDS-PAGE. Accordingly, the purified native lipase exhibited maximal hydrolytic activity at 37°C and pH 7.0, with a positive effect for Mg2+ and Ca2+ metals on its activity. Finally, purified native lipase was immobilized on Amberlite resin (IRC50) and successfully catalyzed the transformation of WCO into biodiesel with a yield of 87.39% as determined by gas chromatography/mass spectrometry (GC/MS) analysis. The physicochemical properties of generated biodiesel have met European standards. Prospective studies include large-scale production of Bacillus subtilis native lipase and testing the efficacy of recombinant lipase for the transformation of WCO into biodiesel.