Isobutanol production from cellobionic acid in Escherichia coli

Microbial Cell Factories

Research

Christine A Rabinovitch-Deere¹  Shuchi H Desai²  Shota Atsumi²  Zhiliang Fan³ 

[1] Department of Chemistry, University of California, Davis, One Shields Ave, 95616, Davis, CA, USA;Department of Chemistry, University of California, Davis, One Shields Ave, 95616, Davis, CA, USA;Microbiology Graduate Group, University of California, Davis, One Shields Ave, 95616, Davis, CA, USA;Microbiology Graduate Group, University of California, Davis, One Shields Ave, 95616, Davis, CA, USA;Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Ave, 95616, Davis, CA, USA;

关键词: Cellobionic acid;    Metabolic engineering;    Isobutanol;   

DOI  :  10.1186/s12934-015-0232-6

 received in 2015-01-09, accepted in 2015-03-25,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundLiquid fuels needed for the global transportation industry can be produced from sugars derived from plant-based lignocellulosics. Lignocellulosics contain a range of sugars, only some of which (such as cellulose) have been shown to be utilizable by microorganisms capable of producing biofuels. Cellobionic acid makes up a small but significant portion of lignocellulosic degradation products, and had not previously been investigated as an utilizable substrate. However, aldonic acids such as cellobionic acid are the primary products of a promising new group of lignocellulosic-degrading enzymes, which makes this compound group worthy of study. Cellobionic acid doesn’t inhibit cellulose degradation enzymes and so its inclusion would increase lignocellulosic degradation efficiency. Also, its use would increase overall product yield from lignocellulose substrate. For these reasons, cellobionic acid has gained increased attention for cellulosic biofuel production.ResultsThis study describes the discovery that Escherichia coli are naturally able to utilize cellobionic acid as a sole carbon source with efficiency comparable to that of glucose and the construction of an E. coli strain able to produce the drop-in biofuel candidate isobutanol from cellobionic acid. The gene primarily responsible for growth of E. coli on cellobionic acid is ascB, a gene previously thought to be cryptic (expressed only after incurring specific mutations in nearby regulatory genes). In addition to AscB, the ascB knockout strain can be complemented by the cellobionic acid phosphorylase from the fungus Neurospora crassa. An E. coli strain engineered to express the isobutanol production pathway was successfully able to convert cellobionic acid into isobutanol. Furthermore, to demonstrate potential application of this strain in a sequential two-step bioprocessing system, E. coli was grown on hydrolysate (that was degraded by a fungus) and was successfully able to produce isobutanol.ConclusionsThese results demonstrate that cellobionic acid is a viable carbon source for biofuel production. This work suggests that with further optimization, a bacteria-fungus co-culture could be used in decreased-cost biomass-based biofuel production systems.

【 授权许可】

Unknown   
© Desai et al.; licensee BioMed Central. 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.