Tuesday, April 30, 2013
Exhibit Hall
The conversion of D-xylose to biofuels and biochemicals has been attracting tremendous research since the last century. Herein, we constructed an oxidative pathway for D-xylose conversion to value-added chemicals using Escherichia coli as the platform. The first three steps of the constructed oxidative pathway are: D-xylose → D-xylonic acid → 2-dehydro-3-deoxy-pentonate → Pyruvate + Glycoaldehyde. An exogenous D-xylose dehydrogenase (Xdh) from Caulobacter crescentus, the recently discovered D-xylonic acid dehydratases (YjhG and YagF) and 2-dehydro-3-deoxy-D-pentonate aldolases (YjhH and YagE) from E. coli K12, were assembled to catalyze those reactions respectively. For better applying this oxidative pathway, the native E. coli D-xylose metabolic pathway (XI-pentose phosphate pathway) was blocked by deleting the D-xylose isomerase gene xylA. This oxidative pathway is independent of the pentose phosphate pathway and also efficient in D-xylose catabolization. More importantly, specific value-added chemicals can be produced by extending this pathway. We have successfully produced D-xylonic aicd, ethylene glycol, glycolic acid and ethanol from D-xylose by modifying this pathway. Among them, ethylene glycol production is the first report of its biosynthesis from biomass. Other high value chemicals such as poly glycolic acid (PGA) and 3,4-dihydroxybutyrate (3,4-DHBA ) also could be produced based on this pathway. Furthermore, this oxidative pathway is not limited in E. coli, other hosts like Saccharomyces cerevisiaealso can be applied as the platform for producing these chemicals from D-xylose.
This work was supported by Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012-0006693).