The potential of brewer's spent grain to improve the production of α-amylase by Bacillus sp. KR-8104 in submerged fermentation system

Brewer's spent grain (BSG) was used as a solid substrate for the production of alpha-amylase by Bacillus sp. KR-8104 in a submerged fermentation system. The production of alpha-amylase was maximized through statistical optimization of the BSG concentration and incubation time using the Doehlert experimental design. The highest tested amount of BSG (5%, w/v) in the optimization process resulted in a 5.1-fold enhancement of the response. Subsequently, we studied the role of the water-soluble and -insoluble fractions of BSG in the production of alpha-amylase. The results revealed that whole BSG had a greater effect on the production of alpha-amylase than each fraction had separately. Finally, when we examined the potential of BSG to replace the constituents of a medium formula, we observed that simultaneously adding BSG, omitting dextrin, and reducing the other ingredients concentration in the culture medium improved the production of alpha-amylase and made the production process more economical.