Isolation, purification and properties of lipase from <i>Pseudomonas aeruginosa</i>

Abstract

Six isolates (Ps1, Ps2, Ps3, Ps4, Ps5 and Ps6) producing lipase were screened from wastewater on a selective medium agar containing Tween 80 or olive oil as the only source of carbon. Isolate Ps5 showed the highest lipase activity which was later identified as Pseudomonas aeruginosa. The effect of media composition was analysed to maximize the production of lipase. The maximum extracellular lipase present in the broth was purified 4 folds with an overall yield of 19.4% through the purification procedure of ammonium sulphate precipitation and diethyl aminoethyl (DEAE) cellulose chromatography. The purified lipase had the maximal activity within the pH range of 6 to 8, with an optimum pH of 7, and within the temperature range of 20 to 35°C, with an optimum temperature for the hydrolysis of olive oil at 30°C. The enzyme activity of P. aeruginosa lipase was enhanced by Ca 2+ and Mg2+ but strongly inhibited by heavy metals such as Zn²⁺, Cu²⁺and Mn²⁺.

Key words: Pseudomonas, lipase, purification, biomass, heavy metals.