A Cost-effective Medium for Enhanced Production of Extracellular á-galactosidase in Solid Substrate Cultures of Aspergillus awamori and A. carbonarius

A.A. El-Gindy; U.F. Ali; Z.M. Ibrahim; Isaac, George;

Abstract


á-Galactosidase (á-Gal) produced by Aspergillus awamori, A. carbonarius, in solid
substrate cultures was investigated. These fungi were screened for á-Gal production on agricultural
by-products (cane baggase, corn bran, soft wood saw dust and soya flour).The results showed that
corn bran added to fermentation medium in the ratio of (1:1,w/v, the initial moisture content [MC],
60.90%) was the best substrate for á-Gal production by A. awamori and A. carbonarius . The
inoculum density of 5.0 × 10 CFU/ml and 5.7×10 CFU/ml were 5 5 the best for A. awamori and A
.carbonarius, respectively. Six days was the best incubation period for maximal production of á-Gal
by the two experimental fungi. Using of yeast extract, malt extract, beef extract, corn steep liquor,
cane molass, beet molass and whey increase the production of á-Gal by both A. awamori and A.
carbonarius. Maximum á-Gal production was obtained when the two experimental fungi were grown
on corn bran fortified with 0.05 % malt extract. The basal growth solution was treated beet molass
and crude whey, in case of A. awamori and A. carbonarius respectively. The crude enzyme was
precipitated by ammonium sulphate (60%) for both A. awamori and A. carbonarius. The enzyme was
partially purified by ion exchange chromatography on bentonite (2.5%) the activity of the enzyme was
6.38 u/ml and 5.62 u/ ml for A. awamori and A. carbonarius respectively. The temperature and pH
optima of partially purified á-Gal of both A. awamori and A .carbonarius were 55 ºC and 4.8,
respectively. Thermostability over a wide range of temperature (30-60 ºC) and pH stability over a
wide range of pH (3.6-4.8). Partially purified (PP) á-Gal of A. awamori was inhibited with Na+, Li+,
Ag2+, Hg2+, Zn2+, Mo2+, Cd2+, Pb2+ and Fe2+ at 1mM & 5mM. Mg2+, Co2+, Mn2+ and Fe3+ slightly
enhanced the enzyme activity at 1mM while at 5mM they caused inhibition. Ca2+ slightly enhanced
the enzyme activity at 5mM. On the other hand, PP á-Gal of A. carbonarius was inhibited with Na+,
Li+, Ca2+, Ag2+, Hg2+, Zn2+, Mo2+, Cd2+ , Pb2+ and Fe2+ at 1mM & 5mM. Co2+ and Fe3+ slightly
enhanced the enzyme activity at 1 mM while at 5 mM caused inhibition. Mg2+ and Mn2+ slightly
enhanced the enzyme activity at 1mM & 5mM. The enzyme was stored at 0, 4, 30, 45 ºC and the
activity was assayed after 5, 10, 15, 20, 25, 30 days. The enzyme was stable when stored at 4 ºC for
20 days for the two experimental fungi.


Other data

Title A Cost-effective Medium for Enhanced Production of Extracellular á-galactosidase in Solid Substrate Cultures of Aspergillus awamori and A. carbonarius
Authors A.A. El-Gindy ; U.F. Ali ; Z.M. Ibrahim ; Isaac, George 
Keywords A. awamori;A. carbonarius;á-Gal;production;purification
Issue Date 2008
Journal Australian Journal of Basic and Applied Sciences 

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