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The XylR variant (R121C and P363S) releases arabinose‐induced catabolite repression on xylose fermentation and enhances coutilization of lignocellulosic sugar mixtures
Author(s) -
Martinez Rodrigo,
Flores Andrew D.,
Dufault Matthew E.,
Wang Xuan
Publication year - 2019
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.27144
Subject(s) - catabolite repression , xylose , arabinose , fermentation , sugar , pentose , biochemistry , fed batch culture , chemistry , xylose metabolism , biology , food science , mutant , gene
Microbial production of fuels and chemicals from lignocellulosic biomass provides a promising alternative to conventional petroleum‐derived routes. However, the heterogeneous sugar composition of lignocellulose prevents efficient microbial sugar co‐fermentation due to carbon catabolite repression, which negatively affects production metrics. We previously discovered that a mutant copy of the transcriptional regulator XylR (P363S and R121C; denoted as XylR*) in Escherichia coli has a higher DNA‐binding affinity than wild‐type XylR, leading to a stronger activation of the d ‐xylose catabolic genes and a release from glucose‐induced repression on xylose fermentation. Here, we showed that XylR* also releases l ‐arabinose‐induced repression on xylose fermentation through altered transcriptional control, enhancing co‐fermentation of arabinose–xylose sugar mixtures in wild‐type E. coli . Integrating xylR* into an ethanologenic E. coli resulted in the coutilization of 96% of the provided glucose–xylose–arabinose mixtures (120 g/L total sugars supplied) with an ethanol yield higher than 90% of the theoretical maximum by simple batch fermentations.