Glucoamylase production by solid-state fermentation using rice flake manufacturing waste products as substrate

Glucoamylase production has been investigated by solid-state fermentation of agro-industrial wastes generated during the processing of paddy to rice flakes (categorized as coarse, medium and fine waste), along with wheat bran and rice powder by a local soil isolate Aspergillus sp. HA-2. Highest enzyme production was obtained with wheat bran (264 +/- 0.64U/gds) followed by coarse waste (211.5 +/- 1.44 U/gds) and medium waste (192.1 +/- 1.15 U/gds) using 10(6) spores/ml as inoculum at 28 2 degrees C, pH 5. A combination of wheat bran and coarse waste (1:1) gave enzyme yield as compared to wheat bran alone. Media supplementation with carbon source (0.04 g/gds) as sucrose in wheat bran and glucose in coarse and medium waste increased enzyme production to 271.2 +/- 0.92, 220.2 +/- 0.75 and 208.2 +/- 1.99 U/gds respectively. Organic nitrogen supplementation (yeast extract and peptone, 0.02 g/gds) showed a higher enzyme production compared to inorganic source. Optimum enzyme activity was observed at 55 degrees C, pH 5. Enzyme activity was enhanced in the presence of calcium whereas presence of EDTA gave reverse effect. (c) 2005 Elsevier Ltd. All rights reserved.