Hyper-production of α-amylase from agro-residual medium with high-glucose in SSF using catabolite derepressed Bacillus subtilis KCC103

Abstract

In Bacillus subtilis KCC103, α-amylase is hyper-produced and α-amylase synthesis is not subject to catabolite repression. The α-amylase was produced from KCC103 by solid-state fermentation (SSF) using agro-residues and oil cakes as growth substrates. The KCC103 was also tested for its resistance to repression by hyper level (>10% w/w) of glucose and xylose on α-amylase production in SSF. Among growth media containing various combinations of agro-residues, the medium with wheat bran and sunflower oil cake supported highest enzyme production (20700 IU (g dry wt)-1). The α-amylase production was enhanced (4.2 folds) by optimizing the growth substrate and the process parameters: the optimal conditions were wheat bran:sun flower oil cake ratio-1:1 (w/w), substrate particle size-500 μm, substrate to flask volume-1:100 (w/v), initial substrate moisture content-90% (v/w), inoculum size-35%, initial medium pH-7.0, growth temperature-37 °C and cultivation time-48 h. α-Amylase production was further enhanced up to 1.7 folds when SSF was carried out using optimized medium supplemented with sugars or yeast extract (1% w/v) under optimized conditions. Supplementation of biomass sugars, glucose or xylose at 20% (w/w), did not repress the synthesis of α-amylase showing the hyper-tolerance of KCC103 to repression by simple sugars on α-amylase production in SSF. © 2010 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim.