TITLE:
Studies on Properties of Lipase Produced from Aspergillus sp. Isolated from Compost Soil
AUTHORS:
Chijioke O. Ezenwelu, Oladejo A. Afeez, Obiano U. Anthony, Okoro A. Promise, Ude-Ezika C. Mmesoma, Oparaji E. Henry
KEYWORDS:
Lipase, Purification, Specific Activity, Precipitation, Purification Folds
JOURNAL NAME:
Advances in Enzyme Research,
Vol.10 No.2,
June
16,
2022
ABSTRACT: Lipase producing Aspergillus was isolated from soil collected from a refuse dump site located at Awka,
Anambra State, Nigeria using standard microbiology and biochemical techniques.
Crude extract of lipase was produced after a successful screening of the
isolates using mineral broth containing p-NPP through submerged fermentation
system with optimized physiologic conditions. Three steps of purification were carried out: Ammonium sulphate, dialysis
and gel filtration (sephadex G-150). Crude extract was precipitated by using
70% saturation of ammonium sulphate at pH 6.0 which gave the optimum precipitation
of the protein with specific activity of 260.56 U/mg. Precipitation using
ammonium sulphate carried out at pH 6.5 and 8.0 gave specific activity of 217
U/mg of the protein. The precipitates were further desalted through dialysis
for twelve hours and specific activity of 343.20 U/mg was recorded from the
dialysate afterwards. Further purification was done by using sephadex G-150 and
specific activity of 490.55 U/mg was recorded from the active pooled fractions.
The purification table showed a 2.32 purification folds of lipase was gotten
after gel filtration (sephadex G-150) with a lipase percentage yield of 2.00%.
The specific activity of lipase increased from 211.81 to 490.55 U/mg.
Characterization of β-galactosidase
gave optima pH and temperature of the enzyme at 6.0 and 60°C respectively.
Kinetic constants: Km and Vmax values were obtained at
various concentrations of p-NPP where 0.32 mM and Vmax of 200.00 μmol/min
respectively. Ca2+ and Co2+ showed greater effect on lipase
activity in a concentration-dependent manner (0.03 - 0.05 M) when compared to
Mn2+ and Fe2+. The results from this study have shown
that lipase produced from filamentous Aspergillus has a wide range of activity over physiologic conditions in regards to
industrial and clinical standard operational procedures.