Organic solvent stable lipase has been isolated from moderately halophilic bacteria of Pseudomonas stutzeri that originally cultivated from the mud crater of “Bleduk Kuwu” at Purwodadi, Central Java, Indonesia. Preliminary purification has been carried out by ammonium sulfate and acetone fractionations. We noted that acetone fractions gave better purification result, and have successfully extracted 29 kDa lipase. This lipase showed the highest activity at pH 8.5 and 50oC. Further characterization of the enzyme showed that the addition of Zn2+ ions improved its activity, but declined when Cu2+ and Fe2+ ions were added. However, this enzyme was apparently not metalloenzyme because its activity still can be detected up to 56% after it was incubated in 10 mM EDTA for one hour. We also noted that PMSF did not significantly inhibit the enzyme activity implying that it probably does not belong to a group of serine hydrolases. The obtained lipase was stable against some polar organic solvents, such as methanol, ethanol, and acetone, as well as non-polar organic solvent, such as n-hexane. Therefore, lipase from Pseudomonas stutzeri has high potential to be developed as biocatalyst for organic synthesis reactions, such as esterification reaction in biodiesel production.
Lipase, Organic solvent-stable, Halophilic bacteria
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