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

•Lipolytic Anoxybacillus gonensins UF7 was isolated from a hot spring.•Its lipase displayed high activity at alkaline pHs and elevated temperatures.•Lipase showed high activity and stability in the presence of methanol.•Lipase could be used as a catalyst for biodiesel production from waste-frying oils.•Anoxybacillus lipase was used for the first time as catalyst for biodiesel production. 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.