Optimization and purification of thermostable lipase produced by Aspergillus ustus grown on soy-bean litters

ABSTRACT

1. Lipase enzyme was produced from A. ustus under optimized cultural conditions [C/N ratio was 0.4/1% i. e the weight of waste material, soy-bean litters, equivalent to 0.4% lipid is 6.48%, and peptone, 1% for 3 days at pH 6.98 in presence of 1 mg/ml FeCl[3] under shake conditions]. 2. The enzyme was extracted and purified by precipitation with [NH[4]][2] SO[4] then by chromatography on DEAE-Sephadex A[50] followed by Gel-filtration on Sephadex G[100]. Recovery was 27.67%. 3. The enzyme was clearly distinguished from lipases previously characterized, On using SDS-PAGE, the final fraction splits into two bands with electrophoretic mobility 0.24 and 0.56, indicating that the molecule consists of two peptide chains with molecular weight 34.670 and 66.70 Daltons with PI 7.1. km and V[max] values were 5.8 g/100ml and 31.2 U/mg protein, respectively. The maximum activity occurred at 37°C and pH 7.5 for 2.5 hrs. The enzyme has thermostability properties. 4. The enzyme protein is rich in essential amino acids as compared with FAO and it seems to be related to the same group of porcine pancreatic lipase