Application of Anoxybacillus gonensins UF7 lipase as a catalyst for biodiesel production from waste frying oils

Abstract

This study was carried out to purify and characterize the lipase of locally isolated bacterium Anoxybacillus gonensis UF7 (GenBank accession: OM328064), and to investigate its applicability as a catalyst for biodiesel production. After ammonium sulphate precipitation and ion-exchange chromatography steps, the lipase of A. gonensis UF7 was purified with a specific activity of 1370 U/mg protein, a purification fold of 13.1 and a recovery yield of 40.65 %. The molecular weight of the enzyme was determined as 73 kDa by SDS-PAGE. The lipase showed maximum activity and stability at pH 8.0 and 60 °C. Its activity and stability were also high in the presence of methanol, ethanol, SDS, Tween-80, Triton X-100, Tween 80, Ca2+ and Mg2+. To prepare biodiesel from waste frying oils using purified lipase, the optimum reaction conditions were determined as a reaction time of 24 h, an enzyme concentration of 3 mL and an oil:methanol ratio of 3:1 (30 mL:10 mL). Transesterification yield was calculated as 87.7 %. The main fatty acid methyl esters of the biodiesel were methyl oleate (50.8 %), methyl palmitate (20.2 %) and methyl linoleate (16.6 %). The usability of lipases of Anoxybacillus strains including A. gonensins as a catalyst in biodiesel production was investigated for the first time in the present study.