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Engineering Escherichia coli to grow constitutively on D-xylose using the carbon-efficient Weimberg pathway

Rossoni, Luca; Carr, Reuben; Baxter, Scott; Cortis, Roxann; Thorpe, Thomas; Eastham, Graham; Stephens, Gill

Authors

Luca Rossoni luca.rossoni@nottingham.ac.uk

Reuben Carr

Scott Baxter

Roxann Cortis

Thomas Thorpe

Graham Eastham graham.eastham@lucite.com

Gill Stephens



Abstract

Bio-production of fuels and chemicals from lignocellulosic C5 sugars usually requires the use of the pentose phosphate pathway (PPP) to produce pyruvate. Unfortunately, the oxidation of pyruvate to acetyl-coenzyme A results in the loss of 33 % of the carbon as CO2, to the detriment of sustainability and process economics. To improve atom efficiency, we engineered Escherichia coli to utilize d-xylose constitutively using the Weimberg pathway, to allow direct production of 2-oxoglutarate without CO2 loss. After confirming enzyme expression in vitro, the pathway expression was optimized in vivo using a combinatorial approach, by screening a range of constitutive promoters whilst systematically varying the gene order. A PPP-deficient (ΔxylAB), 2-oxoglutarate auxotroph (Δicd) was used as the host strain, so that growth on d -xylose depended on the expression of the Weimberg pathway, and variants expressing Caulobacter crescentus xylXAB could be selected on minimal agar plates. The strains were isolated and high-throughput measurement of the growth rates on d-xylose was used to identify the fastest growing variant. This strain contained the pL promoter, with C. crescentus xylA at the first position in the synthetic operon, and grew at 42 % of the rate on d-xylose compared to wild-type E. coli using the PPP. Remarkably, the biomass yield was improved by 53.5 % compared with the wild-type upon restoration of icd activity. Therefore, the strain grows efficiently and constitutively on d-xylose, and offers great potential for use as a new host strain to engineer carbon-efficient production of fuels and chemicals via the Weimberg pathway.

Citation

Rossoni, L., Carr, R., Baxter, S., Cortis, R., Thorpe, T., Eastham, G., & Stephens, G. (in press). Engineering Escherichia coli to grow constitutively on D-xylose using the carbon-efficient Weimberg pathway. Microbiology, 164(3), https://doi.org/10.1099/mic.0.000611

Journal Article Type Article
Acceptance Date Jan 17, 2018
Online Publication Date Feb 5, 2018
Deposit Date Jan 18, 2018
Publicly Available Date Feb 5, 2018
Journal Microbiology
Electronic ISSN 1465-2080
Publisher Microbiology Society
Peer Reviewed Peer Reviewed
Volume 164
Issue 3
DOI https://doi.org/10.1099/mic.0.000611
Keywords Pentose Utilization; D-Xylose; Weimberg Pathway; Constitutive Growth
Public URL http://eprints.nottingham.ac.uk/id/eprint/49172
Publisher URL http://mic.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000611
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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