Evaluating the efficiency of a local isolate of Aspergillus niger to produce the enzyme lipase

Abstract

Sevententh local fungal isolates ,from oil seeds and soil belong to soil Aspergillus including: Aspergillus niger,Aspergillus flavus and Aspergillus fumigatus were sparated and diagnosed .The study investigates the ability of isolated fungi to excrete Lipase using the method of solid media contained Tween80 substance.Aspergillua niger, Which isolated from Pistachio seeds gave the highest growth rate and highest lipase and selected to detect the best condition for growth and production of lipase using liquid media. Lipase enzyme was extracted by cooling centrifugation and partially purified and steps insequence showed the purification of the enzyme produced from the local isolate A.niger .The include precipitation with ammonium sulfate showed a saturation percent between (20-80%). The 60% percent was the gave a high qualitative activity (22.76) unit/mg by (2.16) times of purification and enzyme yield (93.15)% , Thereafter the enzyme solution was passed through an ionic exchange column ,DEAE-Cellulose to (5.54) times to get (58.29) unit/mg with enzyme yield (66.02)% .All parts with enzyme activities were gathered and put under acrylamide column filtration Sephacyl –S300, This step gave (66.92)unit/mg under purification times (6.36) with an enzyme yield (40.36)% .The results indicated that the molecular weight of enzyme was 28,840 Dalton.