Mode of alpha-amylase production by the shochu koji mold Aspergillus kawachii.
Aspergillus kawachii produces two kinds of alpha-amylase, one is an acid-unstable alpha-amylase and the other is an acid-stable alpha-amylase. Because the quality of the shochu depends strongly on the activities of the alpha-amylases, the culture conditions under which these alpha-amylases are produced were examined. In liquid culture, acid-unstable alpha-amylase was produced abundantly, but, acid-stable alpha-amylase was not produced. The acid-unstable alpha-amylase was produced significantly when glycerol or glucose was used as a carbon source, similarly to the use of inducers such as starch or maltose. In liquid culture, A. kawachii assimilated starch at pH 3.0, but no alpha-amylase activity was recognized in the medium. Instead, the alpha-amylase was found to be trapped in the cell wall. The trapped form was identified as acid-unstable alpha-amylase. Usually, acid-unstable alpha-amylase is unstable at pH 3.0, so its stability appeared to be due to its immobilization in the cell wall. In solid-state culture, both kinds of alpha-amylase were produced. The production of acid-stable alpha-amylase seems to be solid-state culture-specific and was affected by the moisture content in the solid medium.
National Research Institute of Brewing, Kagamiyama, Higashihiroshima, Japan.
Kazuki
K
Nagamine
Kenji
K
Murashima
Taku
T
Kato
Hitoshi
H
Shimoi
Kiyoshi
K
Ito
D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000201:enzymology; D003470:Culture Media; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D000516:alpha-Amylases / Q000096:biosynthesis* / Q000302:isolation & purification
D003470:Culture Media; D000516:alpha-Amylases