Screening for Extremophilic Lipase Producing Bacteria: Partial Purification and Characterization of Thermo-Halophilic, Solvent Tolerant Lipase from Bacillus sp.

Abstract

The introduced study aims to isolate potent lipase producing strain from extreme habitats. The aim is extended to characterize the produced enzyme with respect to the effect of salt, temperature, pH and different organic solvents. Tween 80 plate method was used for discriminating lipase producing strains in the isolation step. Lipase activity of the selected isolates was confirmed through Rhodamine B plate assay. The enzyme of the most potent isolate was partially purified using 80% ammonium sulphate, quantified, and characterized using the synthetic substrate, para nitrophenyl laurate (pNP-C12). Twenty-three lipase-producing isolates were screened from different soil samples in Wadi El-Natrun, Egypt. Among the tested strains, a thermo- halo-tolerant bacterial isolate identified as Bacillus sp. was the most potent in terms of lipase production under high temperature and high salt concentration. The enzyme displayed its optimal activity at 60 oC and 2 M NaCl. Moreover, it showed a robust stability in 4M NaCl up to 2 h incubation time. Non-polar solvents have significantly raised the enzyme activity by 300% and 350% for ethyl acetate and n-hexane, respectively. The obtained data introduces useful insights for applying lipases in chemical catalysis and food processing fields.