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).
VTT, Technical Research Centre of Finland, PO Box 1000, FI-02044 VTT, Espoo, Finland. mervi.toivari@vtt.fi
Mervi
M
Toivari
Yvonne
Y
Nygård
Esa-Pekka
EP
Kumpula
Maija-Leena
ML
Vehkomäki
Mojca
M
Benčina
Mari
M
Valkonen
Hannu
H
Maaheimo
Martina
M
Andberg
Anu
A
Koivula
Laura
L
Ruohonen
Merja
M
Penttilä
Marilyn G
MG
Wiebe
D000429:Alcohol Oxidoreductases / Q000096:biosynthesis / Q000235:genetics; D000449:Aldehyde Reductase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016935:Caulobacter crescentus / Q000201:enzymology / Q000235:genetics; D000431:Ethanol / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D008099:Liver / Q000201:enzymology; D060847:Metabolic Engineering / Q000379:methods*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D013552:Swine / Q000378:metabolism; D014574:Uronic Acids / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism*
D014574:Uronic Acids; D000431:Ethanol; D014994:Xylose; D000429:Alcohol Oxidoreductases; C035795:D-xylose dehydrogenase; D000449:Aldehyde Reductase; D005947:Glucose