sp. BUP6 produces a thermotolerant alkaline lipase with -esterification efficiency in producing biodiesel.

The present study describes the characteristics of a thermotolerant and alkaline lipase secreted by sp. BUP6, a novel rumen bacterium isolated from Malabari goat, and its -esterification efficiency in producing biodiesel from used cooking oil (UCO). The extracellular lipase was purified to homogeneity (35.8 times purified with 14.8% yield) employing (NH)SO salt precipitation and Sephadex G-100 chromatography. The apparent molecular weight of this lipase on SDS-PAGE was 35 kDa, the identity of which was further confirmed by MALDI-TOF/MS. The purified lipase was found stable at a pH range of 7-9 with the maximum activity (707 U/ml) at pH 8.2; and was active at the temperature ranging from 35 to 50 °C with the optimum at 45 °C (891 U/ml). Triton X-100 and EDTA had no effect on the activity of lipase; whereas SDS, Tween-80 and β-mercaptoethanol inhibited its activity significantly. Moreover, Ca (1.0 mM) enhanced the activity of lipase (1428 U/ml) by 206% vis-à-vis initial activity; while Zn, Fe and Cu decreased the activity significantly. Using -nitrophenyl palmitate as substrate, the (11.6 mM) and [668.9 μmol/(min/mg)] of the purified lipase were also determined. Crude lipase was used for analyzing its -esterification efficiency with used cooking oil and methanol which resulted in the worthy yield of fatty acid methyl esters, FAME (45%) at 37 °C, indicating its prospects in biodiesel industry. Thus, the lipase secreted by the rumen bacterium, sp. BUP6, offers great potentials to be used in various industries including the production of biodiesel by -esterification.