D. Pokorny et al., ASPERGILLUS-NIGER LIPASES - INDUCTION, ISOLATION AND CHARACTERIZATIONOF 2 LIPASES FROM A MZKI A116 STRAIN, Journal of molecular catalysis. B, Enzymatic, 2(4-5), 1997, pp. 215-222
Aspergillus niger strain MZKI A116 was used to produce lipolytic enzym
es in submerged culture. Lipase production was induced by addition of
olive oil to a complex medium with an initial pH of 5.0. Maximal activ
ity was reached after 70 h in a 15 1 bioreactor at 30 degrees C with a
eration of 0.5 vvm and agitation 400 rpm. Optimal temperature and pH c
onditions for the action of the lipases tested on tributyrin were 45 d
egrees C and pH 7.0. Triacetin and tributyrin were shown to be the bes
t substrates. The presence of iron and silver ions at low concentratio
ns did not alter the activities. Two enzymes possessing lipase activit
y were isolated by acetone precipitation followed by ion-exchange chro
matography. The molecular weights were 43 kDa and 65 kDa with isoelect
ric points of pH 4.1 and 4.2, respectively. The higher molecular weigh
t lipase showed preference toward 1- and 3-positions of the triglyceri
de molecule and was stereoselective for the sn-l position with an enan
tiomeric excess of 20%. It displayed strong activity toward naphthyl,
indolyl, umbelliferyl and resorufin esters and was active on esters of
hydroxynaphthoic acid anilide, while it showed no activity toward est
ers of hydroxypyrene trisulfonic acid.