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 ± 0.64 U/gds) followed by coarse waste (211.5 ± 1.44 U/gds) and medium waste (192.1 ± 1.15 U/gds) using 106 spores/ml as inoculum at 28 ± 2 °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 °C, pH 5. Enzyme activity was enhanced in the presence of calcium whereas presence of EDTA gave reverse effect.