Yi. Yamane et al., A solid-state culture system using a cellulose carrier containing defined medium as a useful tool for investigating characteristics of Koji culture, J BIOSCI BI, 89(1), 2000, pp. 33-39
The purpose of this article is to establish a new solid-state culture syste
m 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 c
arrier with agar, and named it "cellulose agar cube (CA-cube)". In order to
obtain growth conditions similar to koji culture, we then determined the m
oisture 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 observ
ed on the surface of CA-cube with moisture content lower than 63%. The gluc
oamylase production and the production ratio of glucoamylase to alpha-amyla
se (G/A ratio) were both increased exponentially with decreasing moisture c
ontent 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 c
ulture. In addition, the glucoamylase "glaB", which is mainly produced in k
oji culture, was observed in the CA-cube culture with low moisture content.
These results indicate that growth conditions similar to koji culture coul
d be attained by the column reactor culture with the CA-cube.