Production and characterization of amylase by mixed cultures of Aspergilllus flavus and Aspergillus tamarii

Abstract

This study evaluated the potentials of mixed cultures of Aspergillus flavus and A. tamarii used for enhanced amylase production. Amylase producing moulds were screened from the soil by plating on Remazol Brillant Blue-Starch agar. Out of the 800moulds screened, studies were conducted on amylase production of monocultures and mixed cultures of non-aflatoxigenic Aspergillus flavus(A) and Aspergillus tamarii(C) by growing them on rice bran solid media at 30°C for 72h. The synergy between the two moulds was pronounced at 70°C and pH6.0, 7.0 where the enzyme activity of the mixed culture(E) was 2.5times higher than that of the monocultures. Storage stability with Cassava starch and Soyabean flour showed that the maximal enzyme stability of 95% was obtained with 3% (w/v) of Cassava starch at 4°C while 96% enzyme stability was achieved with 4% (w/v) Soya bean flour at 30°C over a period of 8weeks. Thin Layer Chromatography of starch hydrolysates showed a mixture of glucose and maltose from extracts of A with only maltose from C suggesting that A produced glucoamylase and α-amylase while C produced only α-amylase. This study shows that extracts of the mixed cultures contain enzyme complex that can be of high importance in the starch industry.