d-Tagatose manufacture through bio-oxidation of galactitol derived from waste xylose mother liquor?

Green Chemistry Pub Date: 2018-04-16 DOI: 10.1039/C8GC00091C

Abstract

In this study, the bio-oxidation of galactitol to the valuable D-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 (PdPDH) was rapidly identified from a massive number of candidates. When coupled with a water-forming NADH oxidase (StNOX) for environmentally benign cofactor regeneration, subsequent reaction optimization facilitated the complete transformation of 100 g L?1 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.

Graphical abstract: d-Tagatose manufacture through bio-oxidation of galactitol derived from waste xylose mother liquor
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