Abstract
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.