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Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate

BACKGROUND: Interannual variability in precipitation, particularly drought, can affect lignocellulosic crop biomass yields and composition, and is expected to increase biofuel yield variability. However, the effect of precipitation on downstream fermentation processes has never been directly charact...

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Autores principales: Ong, Rebecca Garlock, Higbee, Alan, Bottoms, Scott, Dickinson, Quinn, Xie, Dan, Smith, Scott A., Serate, Jose, Pohlmann, Edward, Jones, Arthur Daniel, Coon, Joshua J., Sato, Trey K., Sanford, Gregg R., Eilert, Dustin, Oates, Lawrence G., Piotrowski, Jeff S., Bates, Donna M., Cavalier, David, Zhang, Yaoping
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5100259/
https://www.ncbi.nlm.nih.gov/pubmed/27826356
http://dx.doi.org/10.1186/s13068-016-0657-0
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author Ong, Rebecca Garlock
Higbee, Alan
Bottoms, Scott
Dickinson, Quinn
Xie, Dan
Smith, Scott A.
Serate, Jose
Pohlmann, Edward
Jones, Arthur Daniel
Coon, Joshua J.
Sato, Trey K.
Sanford, Gregg R.
Eilert, Dustin
Oates, Lawrence G.
Piotrowski, Jeff S.
Bates, Donna M.
Cavalier, David
Zhang, Yaoping
author_facet Ong, Rebecca Garlock
Higbee, Alan
Bottoms, Scott
Dickinson, Quinn
Xie, Dan
Smith, Scott A.
Serate, Jose
Pohlmann, Edward
Jones, Arthur Daniel
Coon, Joshua J.
Sato, Trey K.
Sanford, Gregg R.
Eilert, Dustin
Oates, Lawrence G.
Piotrowski, Jeff S.
Bates, Donna M.
Cavalier, David
Zhang, Yaoping
author_sort Ong, Rebecca Garlock
collection PubMed
description BACKGROUND: Interannual variability in precipitation, particularly drought, can affect lignocellulosic crop biomass yields and composition, and is expected to increase biofuel yield variability. However, the effect of precipitation on downstream fermentation processes has never been directly characterized. In order to investigate the impact of interannual climate variability on biofuel production, corn stover and switchgrass were collected during 3 years with significantly different precipitation profiles, representing a major drought year (2012) and 2 years with average precipitation for the entire season (2010 and 2013). All feedstocks were AFEX (ammonia fiber expansion)-pretreated, enzymatically hydrolyzed, and the hydrolysates separately fermented using xylose-utilizing strains of Saccharomyces cerevisiae and Zymomonas mobilis. A chemical genomics approach was also used to evaluate the growth of yeast mutants in the hydrolysates. RESULTS: While most corn stover and switchgrass hydrolysates were readily fermented, growth of S. cerevisiae was completely inhibited in hydrolysate generated from drought-stressed switchgrass. Based on chemical genomics analysis, yeast strains deficient in genes related to protein trafficking within the cell were significantly more resistant to the drought-year switchgrass hydrolysate. Detailed biomass and hydrolysate characterization revealed that switchgrass accumulated greater concentrations of soluble sugars in response to the drought and these sugars were subsequently degraded to pyrazines and imidazoles during ammonia-based pretreatment. When added ex situ to normal switchgrass hydrolysate, imidazoles and pyrazines caused anaerobic growth inhibition of S. cerevisiae. CONCLUSIONS: In response to the osmotic pressures experienced during drought stress, plants accumulate soluble sugars that are susceptible to degradation during chemical pretreatments. For ammonia-based pretreatment, these sugars degrade to imidazoles and pyrazines. These compounds contribute to S. cerevisiae growth inhibition in drought-year switchgrass hydrolysate. This work discovered that variation in environmental conditions during the growth of bioenergy crops could have significant detrimental effects on fermentation organisms during biofuel production. These findings are relevant to regions where climate change is predicted to cause an increased incidence of drought and to marginal lands with poor water-holding capacity, where fluctuations in soil moisture may trigger frequent drought stress response in lignocellulosic feedstocks. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-016-0657-0) contains supplementary material, which is available to authorized users.
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spelling pubmed-51002592016-11-08 Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate Ong, Rebecca Garlock Higbee, Alan Bottoms, Scott Dickinson, Quinn Xie, Dan Smith, Scott A. Serate, Jose Pohlmann, Edward Jones, Arthur Daniel Coon, Joshua J. Sato, Trey K. Sanford, Gregg R. Eilert, Dustin Oates, Lawrence G. Piotrowski, Jeff S. Bates, Donna M. Cavalier, David Zhang, Yaoping Biotechnol Biofuels Research BACKGROUND: Interannual variability in precipitation, particularly drought, can affect lignocellulosic crop biomass yields and composition, and is expected to increase biofuel yield variability. However, the effect of precipitation on downstream fermentation processes has never been directly characterized. In order to investigate the impact of interannual climate variability on biofuel production, corn stover and switchgrass were collected during 3 years with significantly different precipitation profiles, representing a major drought year (2012) and 2 years with average precipitation for the entire season (2010 and 2013). All feedstocks were AFEX (ammonia fiber expansion)-pretreated, enzymatically hydrolyzed, and the hydrolysates separately fermented using xylose-utilizing strains of Saccharomyces cerevisiae and Zymomonas mobilis. A chemical genomics approach was also used to evaluate the growth of yeast mutants in the hydrolysates. RESULTS: While most corn stover and switchgrass hydrolysates were readily fermented, growth of S. cerevisiae was completely inhibited in hydrolysate generated from drought-stressed switchgrass. Based on chemical genomics analysis, yeast strains deficient in genes related to protein trafficking within the cell were significantly more resistant to the drought-year switchgrass hydrolysate. Detailed biomass and hydrolysate characterization revealed that switchgrass accumulated greater concentrations of soluble sugars in response to the drought and these sugars were subsequently degraded to pyrazines and imidazoles during ammonia-based pretreatment. When added ex situ to normal switchgrass hydrolysate, imidazoles and pyrazines caused anaerobic growth inhibition of S. cerevisiae. CONCLUSIONS: In response to the osmotic pressures experienced during drought stress, plants accumulate soluble sugars that are susceptible to degradation during chemical pretreatments. For ammonia-based pretreatment, these sugars degrade to imidazoles and pyrazines. These compounds contribute to S. cerevisiae growth inhibition in drought-year switchgrass hydrolysate. This work discovered that variation in environmental conditions during the growth of bioenergy crops could have significant detrimental effects on fermentation organisms during biofuel production. These findings are relevant to regions where climate change is predicted to cause an increased incidence of drought and to marginal lands with poor water-holding capacity, where fluctuations in soil moisture may trigger frequent drought stress response in lignocellulosic feedstocks. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-016-0657-0) contains supplementary material, which is available to authorized users. BioMed Central 2016-11-08 /pmc/articles/PMC5100259/ /pubmed/27826356 http://dx.doi.org/10.1186/s13068-016-0657-0 Text en © The Author(s) 2016 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. 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.
spellingShingle Research
Ong, Rebecca Garlock
Higbee, Alan
Bottoms, Scott
Dickinson, Quinn
Xie, Dan
Smith, Scott A.
Serate, Jose
Pohlmann, Edward
Jones, Arthur Daniel
Coon, Joshua J.
Sato, Trey K.
Sanford, Gregg R.
Eilert, Dustin
Oates, Lawrence G.
Piotrowski, Jeff S.
Bates, Donna M.
Cavalier, David
Zhang, Yaoping
Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate
title Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate
title_full Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate
title_fullStr Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate
title_full_unstemmed Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate
title_short Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate
title_sort inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5100259/
https://www.ncbi.nlm.nih.gov/pubmed/27826356
http://dx.doi.org/10.1186/s13068-016-0657-0
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