No abstract

No abstract

No abstract

No abstract

A Brazilian strain of Fusarium solani was tested for extracellular lipase production in peptone-olive oil medium. The fungus produced 10,500 U.L -1 of lipase after 72 hours of cultivation at 25ºC in shake-flask at 120 rpm in a medium containing 3% (w/ v) peptone plus 0.5% (v/v) olive oil. Glucose (1% w/v) was found to inhibit the inductive effect of olive oil. Peptone concentrations below 3% (w/v) resulted in a reduced lipase production while increased olive oil concentration (above 0.5%) did not further stimulate lipase production. The optimum lipase activity was achieved at pH 8.6 and 30ºC and a good enzyme stability (80% activity retention) was observed at pH ranging from 7.6 to 8.6, and the activity rapidly dropped at temperatures above 50ºC. Lipase activity was stimulated by the addition of n-hexane to the culture medium supernatants, in contrast to incubation with water-soluble solvents.

No abstract

A lipases (glycerol ester hydrolases E. C. 3.1.1.3) from a brazilian strain of Penicillium citrinum has been investigated. When the microorganism was cultured in the simple medium (1.0% olive oil and 0.5% yeast extract), using olive oil in as carbon source in the inocula, the enzyme extracted showed maximum activity (409 IU/mL). In addition, decrease of yeast extract concentration also reduces the lipase activity. Nevertheless, when yeast extract was replaced by ammonium sulfate, no activity was detected. Purification by precipitation with ammonium sulfate showed best activity in the 40-60% fraction. The optimum temperature for enzyme activity was found in the range of 34-37 degrees C. However, after 30 min at 60 degrees C, the enzyme was completely inactivated. The enzyme showed optimum at pH 8.0. The dried concentrated fraction (after dialysis and lyophilization) maintained its lipase activity at room temperature (28 degrees C) for 8 mo. This result in lipase stability suggests an application of lipases from P. citrinum in detergents and other products that require a high stability at room temperature.

Mucor miehei lipase was immobilized on magnetic polysiloxane-polyvinyl alcohol particles by covalent binding. The resulting immobilized biocatalyst was recycled by seven assays, with a retained activity around 10% of its initial activity. K m and V max were respectively 228.3 lM and 36.1 U mg of protein )1 for immobilized enzyme. Whereas the optimum temperature remained the same for both soluble and immobilized lipase (45°C), there was a shift in pH profiles after immobilization. Optimum pH for the immobilized lipase was 8.0. Immobilized enzyme showed to be more resistant than soluble lipase when assays were performed out of the optimum temperature or pH.