초록
<P>The maltohexaose-forming, Ca<SUP>2+</SUP>-independent <I>α</I>-amylase gene from<I> Bacillus stearothermophilus</I> (AmyMH) was efficiently expressed in<I> Brevibacillus choshinensis</I> SP3. To improve the production of AmyMH in<I> B. choshinensis</I> SP3, the temperature and initial pH of culture medium were optimized. In addition, single-factor and response surface methodologies were pursued to optimize culture medium. Addition of proline to the culture medium significantly improved the production of recombinant <I>α</I>-amylase in<I> B. choshinensis</I> SP3. This improvement may result from improved cellular integrity of recombinant<I> B. choshinensis</I> SP3 in existence of proline. Culture medium optimization resulted in an 8-fold improvement in <I>α</I>-amylase yield, which reached 1.72 × 10<SUP>4</SUP> U·mL<SUP>−1</SUP>. The recombinant <I>α</I>-amylase was applied to the production of maltose on a laboratory scale. A maltose content of 90.72%, which could be classified as an extremely high maltose syrup, could be achieved using 15% (m/v) corn starch as the substrate. This study demonstrated that the<I> B. choshinensis</I> SP3 expression system was able to produce substantial quantities of recombinant <I>α</I>-amylase that has potential application in the starch industry.</P>