Production of acid-stable alpha-amylase by Aspergillus kawachii during barley Shochu-koji production
1997
Kajiwara, Y. (Sanwa Shurui Co. Ltd., Usa, Oita (Japan)) | Takeshima, N. | Ohba, H. | Omori, T. | Shimoda, M. | Wada, H.
Acid-stable alpha-amylase (asAA) produced by Aspergillus kawachii (IFO4308) during shochu-koji production was investigated. Two types of asAA (asA-1 and asA-2) were purified from barley shochu-koji and their molecular weights were estimated to be 108,000 and 88,000, respectively. The characteristics of the adsorption of asA-1 and asA-2 onto raw starch were different. In barley shochu-koji production, the asA-1 activity increased gradually, but decreased after 24 h incubation. In contrast, the asA-2 activity increased with incubation time. The ratio of asA-1 to total asAA activity (A1/AA ratio) was influenced by temperature. asA-1 was incubated with the acid protease of A. kawachii, and the mixture was subjected to SDS-PAGE analysis. The band corresponding to asA-1 disappeared at 12 h into the incubation time, and an unknown band appeared at this time. The unknown protein possessed almost the same characteristics with respect to alpha-amylase activity and molecular weight as did asA-2. From these results, acid-stable alpha-amylase is concluded to have many forms similar to the glucoamylases of Aspergillus awamori var. kawachi and it is thought that it is formed during shochu-koji production
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