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

Keywords A. awamori;A. carbonarius;á-Gal;production;purification
Issue Date 2008
Journal Australian Journal of Basic and Applied Sciences 
URI http://research.asu.edu.eg/handle/123456789/1927


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