Simultaneous achievement of high ethanol yield and titer in Clostridium thermocellum

Liang Tian; Beth Papanek; Daniel G. Olson; Thomas Rydzak; Evert K. Holwerda; Tianyong Zheng; Jilai Zhou; Marybeth Maloney; Nannan Jiang; Richard J. Giannone; Robert L. Hettich; Adam M. Guss; Lee R. Lynd

doi:10.1186/s13068-016-0528-8

Simultaneous achievement of high ethanol yield and titer in Clostridium thermocellum

Liang Tian, Beth Papanek, Daniel G. Olson, Thomas Rydzak, Evert K. Holwerda, Tianyong Zheng, Jilai Zhou, Marybeth Maloney, Nannan Jiang, Richard J. Giannone, Robert L. Hettich, Adam M. Guss, Lee R. Lynd

Research output: Contribution to journal › Article › peer-review

109 Scopus citations

Abstract

Background: Biofuel production from plant cell walls offers the potential for sustainable and economically attractive alternatives to petroleum-based products. Fuels from cellulosic biomass are particularly promising, but would benefit from lower processing costs. Clostridium thermocellum can rapidly solubilize and ferment cellulosic biomass, making it a promising candidate microorganism for consolidated bioprocessing for biofuel production, but increases in product yield and titer are still needed. Results: Here, we started with an engineered C. thermocellum strain where the central metabolic pathways to products other than ethanol had been deleted. After two stages of adaptive evolution, an evolved strain was selected with improved yield and titer. On chemically defined medium with crystalline cellulose as substrate, the evolved strain produced 22.4 ± 1.4 g/L ethanol from 60 g/L cellulose. The resulting yield was about 0.39 g_ETOH/g_{Gluc eq}, which is 75 % of the maximum theoretical yield. Genome resequencing, proteomics, and biochemical analysis were used to examine differences between the original and evolved strains. Conclusions: A two step selection method successfully improved the ethanol yield and the titer. This evolved strain has the highest ethanol yield and titer reported to date for C. thermocellum, and is an important step in the development of this microbe for industrial applications.

Original language	English
Article number	116
Journal	Biotechnology for Biofuels
Volume	9
Issue number	1
DOIs	https://doi.org/10.1186/s13068-016-0528-8
State	Published - Jun 2 2016

Bibliographical note

Publisher Copyright:
© 2016 The Author(s).

Funding

The genomic resequencing work conducted by the U.S. Department of Energy Joint Genome Institute, a DOE Office of Science User Facility, is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The BioEnergy Science Center is a U.S. Department of Energy Bioenergy Research Center supported by the Office of Biological and Environmental Research in the DOE Office of Science. Notice: This manuscript has been authored by Dartmouth College under Subcontract No. 4000115284 and Contract No. DE-AC05-00OR22725 with U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable world-wide license to publish or reproduce the published form of this manuscript or allow others to do so, for United States Government purposes.

Funders	Funder number
BioEnergy Science Center
U.S. Department of Energy Bioenergy Research Center
U.S. Department of Energy Joint Genome Institute
U.S. Department of Energy	DE-AC02-05CH11231
Office of Science
Biological and Environmental Research

Keywords

Adaptive evolution
Cellulosic ethanol
Clostridium thermocellum
Consolidated bioprocessing

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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Cite this

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title = "Simultaneous achievement of high ethanol yield and titer in Clostridium thermocellum",

abstract = "Background: Biofuel production from plant cell walls offers the potential for sustainable and economically attractive alternatives to petroleum-based products. Fuels from cellulosic biomass are particularly promising, but would benefit from lower processing costs. Clostridium thermocellum can rapidly solubilize and ferment cellulosic biomass, making it a promising candidate microorganism for consolidated bioprocessing for biofuel production, but increases in product yield and titer are still needed. Results: Here, we started with an engineered C. thermocellum strain where the central metabolic pathways to products other than ethanol had been deleted. After two stages of adaptive evolution, an evolved strain was selected with improved yield and titer. On chemically defined medium with crystalline cellulose as substrate, the evolved strain produced 22.4 ± 1.4 g/L ethanol from 60 g/L cellulose. The resulting yield was about 0.39 gETOH/gGluc eq, which is 75 % of the maximum theoretical yield. Genome resequencing, proteomics, and biochemical analysis were used to examine differences between the original and evolved strains. Conclusions: A two step selection method successfully improved the ethanol yield and the titer. This evolved strain has the highest ethanol yield and titer reported to date for C. thermocellum, and is an important step in the development of this microbe for industrial applications.",

keywords = "Adaptive evolution, Cellulosic ethanol, Clostridium thermocellum, Consolidated bioprocessing",

author = "Liang Tian and Beth Papanek and Olson, {Daniel G.} and Thomas Rydzak and Holwerda, {Evert K.} and Tianyong Zheng and Jilai Zhou and Marybeth Maloney and Nannan Jiang and Giannone, {Richard J.} and Hettich, {Robert L.} and Guss, {Adam M.} and Lynd, {Lee R.}",

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doi = "10.1186/s13068-016-0528-8",

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AU - Rydzak, Thomas

AU - Holwerda, Evert K.

AU - Zheng, Tianyong

AU - Zhou, Jilai

AU - Maloney, Marybeth

AU - Jiang, Nannan

AU - Giannone, Richard J.

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AU - Guss, Adam M.

AU - Lynd, Lee R.

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AB - Background: Biofuel production from plant cell walls offers the potential for sustainable and economically attractive alternatives to petroleum-based products. Fuels from cellulosic biomass are particularly promising, but would benefit from lower processing costs. Clostridium thermocellum can rapidly solubilize and ferment cellulosic biomass, making it a promising candidate microorganism for consolidated bioprocessing for biofuel production, but increases in product yield and titer are still needed. Results: Here, we started with an engineered C. thermocellum strain where the central metabolic pathways to products other than ethanol had been deleted. After two stages of adaptive evolution, an evolved strain was selected with improved yield and titer. On chemically defined medium with crystalline cellulose as substrate, the evolved strain produced 22.4 ± 1.4 g/L ethanol from 60 g/L cellulose. The resulting yield was about 0.39 gETOH/gGluc eq, which is 75 % of the maximum theoretical yield. Genome resequencing, proteomics, and biochemical analysis were used to examine differences between the original and evolved strains. Conclusions: A two step selection method successfully improved the ethanol yield and the titer. This evolved strain has the highest ethanol yield and titer reported to date for C. thermocellum, and is an important step in the development of this microbe for industrial applications.

KW - Adaptive evolution

KW - Cellulosic ethanol

KW - Clostridium thermocellum

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Simultaneous achievement of high ethanol yield and titer in Clostridium thermocellum

Abstract

Bibliographical note

Funding

Keywords

UN SDGs

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