초록
<P><B>Abstract</B></P><P>The cocurrent downflow contacting reactor (CDCR) has a high oxygen transfer rate by providing the effective the gas-liquid contact. This property is an advantage for enzyme production. In this study, the CDCR was used for the production of α-amylase by<I>Bacillus amyloliquefaciens</I>for different starch concentrations in the range of 7.5–17.5 g l<SUP>–1</SUP>at constant air and liquid flow rates. The values of the volumetric oxygen transfer coefficient (<I>k<SUB>L</SUB>a</I>) and specific oxygen uptake rate ([FORMULA OMISSION]) were determined during enzyme production. It has been found that the starch concentration has great effect on the enzyme activity. Maximum enzyme activity (1,000 IU ml<SUP>–1</SUP>) was obtained in the fermentation broth containing of 15 g l<SUP>–1</SUP>starch concentration at 37 °C and pH 7 for 28 h. The<I>k<SUB>L</SUB>a</I>and[FORMULA OMISSION]values were determined to be 175.83 h<SUP>–1</SUP>and 47.5 mg O<SUB>2</SUB>g<SUP>–1</SUP>cell h<SUP>–1</SUP>, respectively.</P>