Creation of cellobiose and xylooligosaccharides-coutilizing Escherichia coli displaying both β-glucosidase and β-xylosidase on its cell surface.

We demonstrated direct utilization of xylooligosaccharides using β-xylosidase-displaying Escherichia coli. After screening active β-xylosidases, BSU17580 from Bacillus subtilis or Tfu1616 from Thermobifida fusca YX, were successfully displayed on the E. coli cell surface using Blc or HdeD as anchor proteins, and these transformants directly assimilated xylooligosaccharides as a carbon source. The final OD 600 in minimal medium containing 2% xylooligosaccharides was 1.09 (after 12 h of cultivation) and 1.30 (after 40 h of cultivation). We then constructed an E. coli strain displaying both β-glucosidase and β-xylosidase. β-glucosidase- and β-xylosidase-displaying E. coli was successfully grown on a 1% cellobiose and 1% xylooligosaccharides mixture, and the OD 600 was 1.76 after 10 h of cultivation, which was higher and reached faster than that grown on a glucose/xylose mixture (1.20 after 30 h of cultivation).