Metabolic engineering of Saccharomyces cerevisiae for bioconversion of D-xylose to D-xylonate.

An NAD(+)-dependent D-xylose dehydrogenase, XylB, from Caulobacter crescentus was expressed in Saccharomyces cerevisiae, resulting in production of 17 ± 2 g D-xylonate l(-1) at 0.23 gl(-1)h(-1) from 23 g D-xylose l(-1) (with glucose and ethanol as co-substrates). D-Xylonate titre and production rate were increased and xylitol production decreased, compared to strains expressing genes encoding T. reesei or pig liver NADP(+)-dependent D-xylose dehydrogenases. D-Xylonate accumulated intracellularly to ∼70 mgg(-1); xylitol to ∼18 mgg(-1). The aldose reductase encoding gene GRE3 was deleted to reduce xylitol production. Cells expressing D-xylonolactone lactonase xylC from C. crescentus with xylB initially produced more extracellular D-xylonate than cells lacking xylC at both pH 5.5 and pH 3, and sustained higher production at pH 3. Cell vitality and viability decreased during D-xylonate production at pH 3.0. An industrial S. cerevisiae strain expressing xylB efficiently produced 43 g D-xylonate l(-1) from 49 g D-xylose l(-1). Copyright © 2012 Elsevier Inc. All rights reserved.

Citation

Mervi Toivari, Yvonne Nygård, Esa-Pekka Kumpula, Maija-Leena Vehkomäki, Mojca Benčina, Mari Valkonen, Hannu Maaheimo, Martina Andberg, Anu Koivula, Laura Ruohonen, Merja Penttilä, Marilyn G Wiebe. Metabolic engineering of Saccharomyces cerevisiae for bioconversion of D-xylose to D-xylonate. Metabolic engineering. 2012 Jul;14(4):427-36

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PMID: 22709678

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