Extraction and purification of hydrolytic enzymes from activated sludge

Abstract

A major proportion of the organic matter contained by domestic wastewater is mainly formed by lipids, proteins and carbohydrates. In order to degrade this organic matter, microorganisms produce hydrolytic enzymes like proteases, lipases and other enzymes that cannot be produced by standard cultivation techniques, which makes its recovery of interest. In the present study protease and lipase were extracted by using magnetic stirring and ultrasound disintegration combined with different additives. It was observed that the concentration of Triton X100 has a great influence in the extraction of protease, but it has no effect in the extraction of lipase. Samples obtained after ultrasound disintegration with 0% and 2% Triton X100 were further purified by precipitation with ammonium sulphate and dialysis. These samples were frozen and lyophilized in order to recover them in powder form. The optimal process for the recovery of lipase was a combination of ultrasound treatment using 0% TX100, followed by dialysis and lyophilization. This process allowed recovering around 23 lipase units/g solid.