Isolation, purification and properties of lipase from Pseudomonas aeruginosa

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 Zn 2+ , Cu 2+ and Mn 2+ . Key words : Pseudomonas , lipase, purification, biomass, heavy metals.

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