Purification and characterization of lipase from solvent tolerant Pseudomonas aeruginosa PseA

Lipase from a solvent tolerant strain of Pseudomonas aeruginosa PseA has been purified by gel exclusion chromatography leading to 8.6-fold purification and 51.6% recovery. Mr of purified lipase as determined by SIDS-PAGE was estimated to be approximately 60 kDa. The optimum pH and temperature for activity of lipase were found to be 8.0 and 40 degrees C. The lipase was found to be stable in the pH range 6-8.5 and temperature range 25-50 degrees C. It was stable in presence of divalent metal ions like Ca2+ Mg2+ whereas Cu2+ and Zn2+ were found to be inhibitory. The enzyme activity was not affected significantly by 1mM EDTA. P-Mercaptoethanol reduced the enzyme activity to 48% after 1 h whereas glutathione activated the lipase. Serine inhibitor PMSF showed no reduction in enzyme activity. Non-ionic detergents Tween-80 and Brij-35 stimulated the lipase activity. Cationic surfactant CTAB inhibited the enzyme activity whereas anionic surfactants sodium deoxycholate caused only 10% reduction in activity. Lipase preferred longer carbon chain (Cl 6) fatty acid ester substrates over the shorter ones and showed random positional specificity for triolein hydrolysis. (C) 2008 Elsevier Ltd. All rights reserved.