Purification and characterization of Lipase Produced by Aspergillus oryzae CJLU-31 isolated from waste cooking oily soil

Abstract

Lipase was one of the most important industrial enzymes and has diverse applications in food industry, detergent industry, fats and oil hydrolysis, peptide synthesis and pharmaceutical industries. The aim of this study was focused on isolation of a lipase producing strain from waste cooking oily soil and characterization of the lipase. The strain, Aspergillus oryzae CJLU-31 was isolated from the waste cooking oily soil and identified by ITS rDNA analysis. The lipase from Aspergillus oryzae CJLU-31 was purified by ammonium sulfate precipitation and two-step chromatography. The results showed that the purified lipase had a specific activity of 11552.2 U mg-1, 23.9-fold purification factor and molecular mass of 27 kDa by Sodium Dodecyl Sulfate-polyacrylamide Gel Electrophoresis (SDS-PAGE). The purified lipase showed higher activity when the waste cooking oil was used as the substrate. It also showed maximum activity and stability at pH 4.0 and 40°C. The lipase retained high activity over ranges of pH (2-5) and temperature (30-50°C). It was enhanced by low concentration metal ions, such as Ki,L ii, Mg2+, Zn2+,M n2+ and Ca2+ while inhibited by Fez+,F e3+ and Cu2+.It showed high stability in the presence of lower polarity organic solvents and activated in 0.1% polyvinyl alcohol-124. The lim and Vmax of the lipase acting on olive oil were 0.11 and 0.41 mM min-1, respectively. Heating and cooling refold-treatment activated the lipase. These features provided the lipase from Aspergillus oryzae CJLU-31 as a potential application for lipase-catalyzed synthesis of fatty acid methyl esters (biohesel) using waste cooking oil. © 2012 Academic Journals Inc.