A solid-state culture system using a cellulose carrier containing defined medium as a useful tool for investigating characteristics of koji culture.
The purpose of this article is to establish a new solid-state culture system that uses a defined medium and allows control of the chemical factors in the medium in solid-state cultivation. To achieve this purpose, we produced a solid substrate, in which the defined medium was packed in a cellulose carrier with agar, and named it "cellulose agar cube (CA-cube)". In order to obtain growth conditions similar to koji culture, we then determined the moisture content of the CA-cube. Five runs of column reactor operations were carried out at various moisture contents of the CA-cube in the range of 50-90%. A very similar mycelial morphology to that of koji culture was observed on the surface of CA-cube with moisture content lower than 63%. The glucoamylase production and the production ratio of glucoamylase to alpha-amylase (G/A ratio) were both increased exponentially with decreasing moisture content and reached 237.5 units per g dry solid and 13.59, respectively, at the moisture content of 50%, which are almost comparable to those of koji culture. In addition, the glucoamylase "glaB", which is mainly produced in koji culture, was observed in the CA-cube culture with low moisture content. These results indicate that growth conditions similar to koji culture could be attained by the column reactor culture with the CA-cube.
Yamane
Y
Y
Suishin Yamane-Honten Co. Ltd., 353-2 Higashi-machi, Mihara 723-0011, Japan.
Yoshii
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M
Mikami
S
S
Fukuda
H
H
Kizaki
Y
Y