Purification and Characterization of Lipase from Rhizomucor miehei

The production of Rhizomucor miehei lipase by solid state fermentation by growing the fungi for 5 days at room temperature on wheat bran medium with a moisture content of 0.75 mL/g is described. The purification of this extracellular enzyme to apparent homogeneity employing a two-step purification sequence using ion-exchange and Octyl-Sepharose affinity chromatography with 135-fold purity and 12% recovery is reported. The purified extracellular enzyme displays maximum activity at pH 7.0 and 65°C. The characteristic feature of this enzyme is its thermostability, retaining 90% of its activity upon exposure to 65°C for 30 min. Further, organic solvents like ethanol and acetone have a stimulatory effect on the lipase activity. But, metal ions such as Mg²⁺, Mn²⁺, Co²⁺, Zn²⁺, Hg²⁺ and Fe²⁺ or EDTA, p-chloromercuric benzoate each at 1mM concentration have a profound inhibitory effect on its catalytic activity. These properties together with its stability in organic solvents could form a basis for further characterization of the enzyme as a potential candidate for exploitation at industrial level.