Production of Acid-Stable α-Amylase by Aspergillus kawachii during Barley Shochu-Koji Production

概要

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Acid-stable α-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 desappeared 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 α-amylase activity and molecular weight as did asA-2. From these results, acid-stable α-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.
社団法人日本生物工学会の論文
1997-09-25