High yield production of d-xylonic acid from d-xylose using engineered Escherichia coli

An engineered Escherichia coli was constructed to produce d-xylonic acid, one of the top 30 high-value chemicals identified by US Department of Energy. The native pathway for d-xylose catabolism in E. coli W3110 was blocked by disrupting xylose isomerase (XI) and xylulose kinase (XK) genes. The native pathway for xylonic acid catabolism was also blocked by disrupting two genes both encoding xylonic acid dehydratase (yagE and yjhG). Through the introduction of a d-xylose dehydrogenase from Caulobacter crescentus, a d-xylonic acid producing E. coli was constructed. The recombinant E. coli produced up to 39.2 g L−1d-xylonic acid from 40 g L−1d-xylose in M9 minimal medium. The average productivity was as high as 1.09 g L−1 h−1 and no gluconic acid byproduct was produced. These results suggest that the engineered E. coli has a promising application for the industrial-scale production of d-xylonic acid.

► Both xylose and xylonic acid metabolic pathways are blocked in Escherichia coli W3110.
► A xylose dehydrogenase is introduced into modified strain.
► Above 39 g L−1d-xylonic acid was produced out of 40 g L−1d-xylose with 1.09 g L−1 h−1 productivity, no gluconic acid is produced.
► A novel pathway for xylose metabolism could be inferred from this research.