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 SDS–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 °C. The lipase was found to be stable in the pH range 6–8.5 and temperature range 25–50 °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 1 mM EDTA. β-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 (C16) fatty acid ester substrates over the shorter ones and showed random positional specificity for triolein hydrolysis.