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Solvent-tolerant lipase produced by Bacillus sp. DM9K3 has been isolated from the hypersaline area, White Rann of Kachchh, Gujarat, India. The strain initially showed lipase activity of 11.1 U/mL in a basal medium which increased to 52.0 U/mL under optimized culture conditions. Bacillus sp. DM9K3 exhibited stability at 7% salinity, pH 9.0 and 50°C. The extracellular lipase was partially purified by acetone precipitation followed by DEAE-cellulose resulting in 39-fold purification with 40% yield. Metals ions such as Mg2+, Ca2+ and K+ showed enhanced enzyme activity. EDTA did not have a significant effect on activity suggesting that lipase is not metalloenzyme. The lipase under study showed the highest activity when palmitate (C16) was used as a substrate and was also highly stable in organic solvents such as cyclooctane and benzene. The partially purified enzyme was immobilized for increasing the efficiency of the ethyl caprylate (an orange flavored ester) synthesis in the presence of cyclooctane. Additionally, lipase of Bacillus sp. DM9K3 was explored for biodegradation of polycaprolactone microspheres and showed promising results for potential applications in drug delivery system. [ABSTRACT FROM AUTHOR]

The present study describes the characteristics of a thermotolerant and alkaline lipase secreted by Pseudomonas sp. BUP6, a novel rumen bacterium isolated from Malabari goat, and its trans-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 para-nitrophenyl palmitate as substrate, the K (11.6 mM) and V [668.9 μmol/(min/mg)] of the purified lipase were also determined. Crude lipase was used for analyzing its trans-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, Pseudomonas sp. BUP6, offers great potentials to be used in various industries including the production of biodiesel by trans-esterification. [ABSTRACT FROM AUTHOR]