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

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)