Engineering efficient xylose metabolism into an acetic acid-tolerant Zymomonas mobilis strain by introducing adaptation-induced mutations.
The impact of the two adaptation-induced mutations in an improved xylose-fermenting Zymomonas mobilis strain was investigated. The chromosomal mutation at the xylose reductase gene was critical to xylose metabolism by reducing xylitol formation. Together with the plasmid-borne mutation impacting xylose isomerase activity, these two mutations accounted for 80 % of the improvement achieved by adaptation. To generate a strain fermenting xylose in the presence of high acetic acid concentrations, we transferred the two mutations to an acetic acid-tolerant strain. The resulting strain fermented glucose + xylose (each at 5 % w/v) with 1 % (w/v) acetic acid at pH 5.8 to completion with an ethanol yield of 93.4 %, outperforming other reported strains. This work demonstrated the power of applying molecular understanding in strain improvement.
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0100, USA.
Manoj
M
Agrawal
Yun
Y
Wang
Rachel Ruizhen
RR
Chen
D019342:Acetic Acid / Q000378:metabolism; D000449:Aldehyde Reductase / Q000235:genetics* / Q000378:metabolism; D018533:Biomass; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation / Q000235:genetics; D055786:Gene Knockout Techniques; D005818:Genetic Engineering / Q000379:methods; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D015202:Protein Engineering; D014993:Xylitol / Q000378:metabolism; D014994:Xylose / Q000378:metabolism*; D017355:Zymomonas / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*
D000431:Ethanol; D014994:Xylose; D000449:Aldehyde Reductase; D005947:Glucose; D019342:Acetic Acid; D014993:Xylitol