초록
<P><B>ABSTRACT</B></P><P>Rare sugars have various known biological functions and potential for applications in pharmaceutical, cosmetics, and food industries. Here we designed and constructed a recombination pathway in <I>Corynebacterium glutamicum</I>, in which dihydroxyacetone phosphate (DHAP), an intermediate of the glycolytic pathway, and a variety of aldehydes were condensed to synthesize rare ketoses sequentially by rhamnulose‐1‐phosphate aldolase (RhaD) and fructose‐1‐phosphatase (YqaB) obtained from <I>Escherichia coli</I>. A wild‐type strain harboring this artificial pathway had the ability to produce <SMALL>D</SMALL>‐sorbose and <SMALL>D</SMALL>‐psicose using <SMALL>D</SMALL>‐glyceraldehyde and glucose as the substrates. The <I>tpi</I> gene, encoding triose phosphate isomerase was further deleted, and the concentration of DHAP increased to nearly 20‐fold relative to that of the wild‐type. After additional optimization of expression levels from <I>rhaD</I> and <I>yqaB</I> genes and of the fermentation conditions, the engineered strain SY6(pVRTY) exhibited preferable performance for rare ketoses production. Its yield increased to 0.59 mol/mol <SMALL>D</SMALL>‐glyceraldehyde from 0.33 mol/mol <SMALL>D</SMALL>‐glyceraldehyde and productivity to 2.35 g/L h from 0.58 g/L h. Moreover, this strain accumulated 19.5 g/L of <SMALL>D</SMALL>‐sorbose and 13.4 g/L of <SMALL>D</SMALL>‐psicose using a fed‐batch culture mode under the optimal conditions. In addition, it was verified that the strain SY6(pVRTY) meanwhile had the ability to synthesize C4, C5, C6, and C7 rare ketoses when a range of representative achiral and homochiral aldehydes were applied as the substrates. Therefore, the platform strain exhibited the potential for microbial production of rare ketoses and deoxysugars. Biotechnol. Bioeng. 2015;112: 168–180. © 2014 Wiley Periodicals, Inc.</P>