Abstract
d-Xylonate was produced from d-xylose using Kluyveromyces lactis strains which expressed the gene for NADP +-dependent d-xylose dehydrogenase from Trichoderma reesei (xyd1). Up to 19±2g d-xylonatel -1 was produced when K. lactis expressing xyd1 was grown on 10.5gd-galactosel -1 and 40g d-xylosel -1. Intracellular accumulation of d-xylonate (up to ~70mg [gbiomass] -1) was observed.d-Xylose was metabolised to d-xylonate, xylitol and biomass. Oxygen could be reduced to 6mmolO 2l -1h -1 without loss in titre or production rate, but metabolism of d-xylose and xylitol were more efficient when 12mmolO 2l -1h -1 were provided.d-Xylose uptake was not affected by deletion of either the d-xylose reductase (XYL1) or a putative xylitol dehydrogenase encoding gene (XYL2) in xyd1 expressing strains. K. lactis xyd1Δ XYL1 did not produce extracellular xylitol and produced more d-xylonate than the xyd1 strain containing the endogenous XYL1. K. lactis xyd1Δ. XYL2 produced high concentrations of xylitol and significantly less d-xylonate than the xyd1 strain with the endogenous XYL2.
| Original language | English |
|---|---|
| Pages (from-to) | 383-391 |
| Journal | Metabolic Engineering |
| Volume | 13 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 1 Jul 2011 |
| MoE publication type | A1 Journal article-refereed |
Funding
Technical assistance of Tarja Laakso, Outi Könönen and Tuuli Teikari is gratefully acknowledged. This study was financially supported by the Academy of Finland through the Centre of Excellence in White Biotechnology—Green Chemistry (grant 118573 ). The financial support of the European Commission through the Sixth Framework Programme Integrated Project BioSynergy ( 038994-SES6 ) is also gratefully acknowledged.
Keywords
- Aeration
- D-xylonic acid
- D-xylose
- D-xylose reductase
- K. lactis
- Xylitol dehydrogenase