초록
<P>In this study, the bio-oxidation of galactitol to the valuable <SMALL>D</SMALL>-tagatose is presented. This proposed strategy could start with the refined by-product of waste xylose mother liquor formed by chemical hydrogenation. Through a computationally guided enzyme screening approach, a robust polyol dehydrogenase (<I>Pd</I>PDH) was rapidly identified from a massive number of candidates. When coupled with a water-forming NADH oxidase (<I>St</I>NOX) for environmentally benign cofactor regeneration, subsequent reaction optimization facilitated the complete transformation of 100 g L<SUP>−1</SUP> galactitol into the desired product within 15 h, with a yield of 91% in a 2 L scale preparative reaction. Compared to the current enzymatic isomerization system, our approach avoids low conversion, high operative temperatures and by-product formation, while enabling simplified product isolation.</P><P>Graphic Abstract</P><P>Practical “green” manufacture of <SMALL>D</SMALL>-tagatose through a bi-enzymatic coupled system from galactitol refined from the waste xylose mother liquor is presented.<BR/><IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c8gc00091c'/><BR/></P>