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

摘要

In Bacillus subtilis KCC103, alpha-amylase is hyper-produced and alpha-amylase synthesis is not subject to catabolite repression. The alpha-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 alpha-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 alpha-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 mum, 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 degrees C and cultivation time-48 h. alpha-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 alpha-amylase showing the hyper-tolerance of KCC103 to repression by simple sugars on alpha-amylase production in SSF.