چکیده (انگلیسی):

The purpose of this study was to isolate, purify and optimize the production conditionsof an organic solvent tolerant and thermostable lipase from Acinetobacter sp. AU07 isolatedfrom distillery waste. The lipase production was optimized by response surface methodol-ogy, and a maximum production of 14.5 U/mL was observed at 30◦C and pH 7, using a 0.5%(v/v) inoculum, 2% (v/v) castor oil (inducer), and agitation 150 rpm. The optimized condi-tions from the shake flask experiments were validated in a 3 L lab scale bioreactor, and thelipase production increased to 48 U/mL. The enzyme was purified by ammonium sulfateprecipitation and ion exchange chromatography and the overall yield was 36%. SDS-PAGEindicated a molecular weight of 45 kDa for the purified protein, and Matrix assisted laserdesorption/ionization time of flight analysis of the purified lipase showed sequence sim-ilarity with GDSL family of lipases. The optimum temperature and pH for activity of theenzyme was found to be 50◦C and 8.0, respectively. The lipase was completely inhibited byphenylmethylsulfonyl fluoride but minimal inhibition was observed when incubated withethylenediaminetetraacetic acid and dithiothreitol. The enzyme was stable in the presenceof non-polar hydrophobic solvents. Detergents like SDS inhibited enzyme activity; however,there was minimal loss of enzyme activity when incubated with hydrogen peroxide, Tween80 and Triton X-100. The kinetic constants (Kmand Vmax) revealed that the hydrolytic activ-ity of the lipase was specific to moderate chain fatty acid esters. The Vmax, Kmand Vmax/Kmratio of the enzyme were 16.98 U/mg, 0.51 mM, and 33.29, respectively when 4-nitrophenylpalmitate was used as a substrate.© 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. This isan open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).