Extracellular lipase of Aspergillus terreus var. africanus (CBS 130.55): production, purification and characterisation

An extracellular lipase was optimally produced by Aspergillus terreus var. africanus (CBS 130.55) after 4 days of submerged fermentation at 30°C, initial pH 6, agitation rate of 150 rpm, using COO(NH 4 ) 2 H 2 O, olive oil and K 2 HPO 4 as nitrogen, carbon and phosphorous sources, respectively. The enzyme was purified to electrophoretic homogeneity and its maximum activity was recorded at pH 7 and 35°C and was stimulated by Ba +2 , Mg +2 and Na +1 . Sugars, polyhydric alcohols and metal ions enhanced the enzyme’s thermal stability. In the presence of 10 mM glucose or Ba 2+ , T m (midpoint of thermal inactivation) was recorded at 57°C and 60°C after 60 min, respectively, while T 1/2 were found to be 17 and 13 weeks at 4°C or −15°C, respectively. Molecular mass, V max, K m and K cat of the enzyme were found to be 42.5 ± 0.9 kDa, 63.10 mM ml −1 min −1 , 0.85 mM, and 1.62 mM ml −1 min −1 , respectively. Possible participation of the SH group in the purified lipase was suggested and its glycoprotein nature was confirmed. The purified enzyme showed a reasonable stability with some commercial detergents.