Cargando…

Evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach

BACKGROUND: The inherent recalcitrance of lignocellulosic biomass is one of the major economic hurdles for the production of fuels and chemicals from biomass. Additionally, lignin is recognized as having a negative impact on enzymatic hydrolysis of biomass, and as a result much interest has been pla...

Descripción completa

Detalles Bibliográficos
Autores principales: Yee, Kelsey L, Rodriguez Jr, Miguel, Tschaplinski, Timothy J, Engle, Nancy L, Martin, Madhavi Z, Fu, Chunxiang, Wang, Zeng-Yu, Hamilton-Brehm, Scott D, Mielenz, Jonathan R
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3503607/
https://www.ncbi.nlm.nih.gov/pubmed/23146305
http://dx.doi.org/10.1186/1754-6834-5-81
_version_ 1782250471670415360
author Yee, Kelsey L
Rodriguez Jr, Miguel
Tschaplinski, Timothy J
Engle, Nancy L
Martin, Madhavi Z
Fu, Chunxiang
Wang, Zeng-Yu
Hamilton-Brehm, Scott D
Mielenz, Jonathan R
author_facet Yee, Kelsey L
Rodriguez Jr, Miguel
Tschaplinski, Timothy J
Engle, Nancy L
Martin, Madhavi Z
Fu, Chunxiang
Wang, Zeng-Yu
Hamilton-Brehm, Scott D
Mielenz, Jonathan R
author_sort Yee, Kelsey L
collection PubMed
description BACKGROUND: The inherent recalcitrance of lignocellulosic biomass is one of the major economic hurdles for the production of fuels and chemicals from biomass. Additionally, lignin is recognized as having a negative impact on enzymatic hydrolysis of biomass, and as a result much interest has been placed on modifying the lignin pathway to improve bioconversion of lignocellulosic feedstocks. RESULTS: Down-regulation of the caffeic acid 3-O-methyltransferase (COMT) gene in the lignin pathway yielded switchgrass (Panicum virgatum) that was more susceptible to bioconversion after dilute acid pretreatment. Here we examined the response of these plant lines to milder pretreatment conditions with yeast-based simultaneous saccharification and fermentation and a consolidated bioprocessing approach using Clostridium thermocellum, Caldicellulosiruptor bescii and Caldicellulosiruptor obsidiansis. Unlike the S. cerevisiae SSF conversions, fermentations of pretreated transgenic switchgrass with C. thermocellum showed an apparent inhibition of fermentation not observed in the wild-type switchgrass. This inhibition can be eliminated by hot water extraction of the pretreated biomass, which resulted in superior conversion yield with transgenic versus wild-type switchgrass for C. thermocellum, exceeding the yeast-based SSF yield. Further fermentation evaluation of the transgenic switchgrass indicated differential inhibition for the Caldicellulosiruptor sp. strains, which could not be rectified by additional processing conditions. Gas chromatography–mass spectrometry (GC-MS) metabolite profiling was used to examine the fermentation broth to elucidate the relative abundance of lignin derived aromatic compounds. The types and abundance of fermentation-derived-lignin constituents varied between C. thermocellum and each of the Caldicellulosiruptor sp. strains. CONCLUSIONS: The down-regulation of the COMT gene improves the bioconversion of switchgrass relative to the wild-type regardless of the pretreatment condition or fermentation microorganism. However, bacterial fermentations demonstrated strain-dependent sensitivity to the COMT transgenic biomass, likely due to additional soluble lignin pathway-derived constituents resulting from the COMT gene disruption. Removal of these inhibitory constituents permitted completion of fermentation by C. thermocellum, but not by the Caldicellulosiruptor sp. strains. The reason for this difference in performance is currently unknown.
format Online
Article
Text
id pubmed-3503607
institution National Center for Biotechnology Information
language English
publishDate 2012
publisher BioMed Central
record_format MEDLINE/PubMed
spelling pubmed-35036072012-11-22 Evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach Yee, Kelsey L Rodriguez Jr, Miguel Tschaplinski, Timothy J Engle, Nancy L Martin, Madhavi Z Fu, Chunxiang Wang, Zeng-Yu Hamilton-Brehm, Scott D Mielenz, Jonathan R Biotechnol Biofuels Research BACKGROUND: The inherent recalcitrance of lignocellulosic biomass is one of the major economic hurdles for the production of fuels and chemicals from biomass. Additionally, lignin is recognized as having a negative impact on enzymatic hydrolysis of biomass, and as a result much interest has been placed on modifying the lignin pathway to improve bioconversion of lignocellulosic feedstocks. RESULTS: Down-regulation of the caffeic acid 3-O-methyltransferase (COMT) gene in the lignin pathway yielded switchgrass (Panicum virgatum) that was more susceptible to bioconversion after dilute acid pretreatment. Here we examined the response of these plant lines to milder pretreatment conditions with yeast-based simultaneous saccharification and fermentation and a consolidated bioprocessing approach using Clostridium thermocellum, Caldicellulosiruptor bescii and Caldicellulosiruptor obsidiansis. Unlike the S. cerevisiae SSF conversions, fermentations of pretreated transgenic switchgrass with C. thermocellum showed an apparent inhibition of fermentation not observed in the wild-type switchgrass. This inhibition can be eliminated by hot water extraction of the pretreated biomass, which resulted in superior conversion yield with transgenic versus wild-type switchgrass for C. thermocellum, exceeding the yeast-based SSF yield. Further fermentation evaluation of the transgenic switchgrass indicated differential inhibition for the Caldicellulosiruptor sp. strains, which could not be rectified by additional processing conditions. Gas chromatography–mass spectrometry (GC-MS) metabolite profiling was used to examine the fermentation broth to elucidate the relative abundance of lignin derived aromatic compounds. The types and abundance of fermentation-derived-lignin constituents varied between C. thermocellum and each of the Caldicellulosiruptor sp. strains. CONCLUSIONS: The down-regulation of the COMT gene improves the bioconversion of switchgrass relative to the wild-type regardless of the pretreatment condition or fermentation microorganism. However, bacterial fermentations demonstrated strain-dependent sensitivity to the COMT transgenic biomass, likely due to additional soluble lignin pathway-derived constituents resulting from the COMT gene disruption. Removal of these inhibitory constituents permitted completion of fermentation by C. thermocellum, but not by the Caldicellulosiruptor sp. strains. The reason for this difference in performance is currently unknown. BioMed Central 2012-11-12 /pmc/articles/PMC3503607/ /pubmed/23146305 http://dx.doi.org/10.1186/1754-6834-5-81 Text en Copyright ©2012 Yee et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research
Yee, Kelsey L
Rodriguez Jr, Miguel
Tschaplinski, Timothy J
Engle, Nancy L
Martin, Madhavi Z
Fu, Chunxiang
Wang, Zeng-Yu
Hamilton-Brehm, Scott D
Mielenz, Jonathan R
Evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach
title Evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach
title_full Evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach
title_fullStr Evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach
title_full_unstemmed Evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach
title_short Evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach
title_sort evaluation of the bioconversion of genetically modified switchgrass using simultaneous saccharification and fermentation and a consolidated bioprocessing approach
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3503607/
https://www.ncbi.nlm.nih.gov/pubmed/23146305
http://dx.doi.org/10.1186/1754-6834-5-81
work_keys_str_mv AT yeekelseyl evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach
AT rodriguezjrmiguel evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach
AT tschaplinskitimothyj evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach
AT englenancyl evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach
AT martinmadhaviz evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach
AT fuchunxiang evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach
AT wangzengyu evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach
AT hamiltonbrehmscottd evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach
AT mielenzjonathanr evaluationofthebioconversionofgeneticallymodifiedswitchgrassusingsimultaneoussaccharificationandfermentationandaconsolidatedbioprocessingapproach