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Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates
BACKGROUND: Presence of inhibitory chemicals in lignocellulose hydrolysates is a major hurdle for production of second-generation bioethanol. Especially cheaper pre-treatment methods that ensure an economical viable production process generate high levels of these inhibitory chemicals. The effect of...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8034183/ https://www.ncbi.nlm.nih.gov/pubmed/33836811 http://dx.doi.org/10.1186/s13068-021-01935-9 |
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author | Vanmarcke, Gert Demeke, Mekonnen M. Foulquié-Moreno, Maria R. Thevelein, Johan M. |
author_facet | Vanmarcke, Gert Demeke, Mekonnen M. Foulquié-Moreno, Maria R. Thevelein, Johan M. |
author_sort | Vanmarcke, Gert |
collection | PubMed |
description | BACKGROUND: Presence of inhibitory chemicals in lignocellulose hydrolysates is a major hurdle for production of second-generation bioethanol. Especially cheaper pre-treatment methods that ensure an economical viable production process generate high levels of these inhibitory chemicals. The effect of several of these inhibitors has been extensively studied with non-xylose-fermenting laboratory strains, in synthetic media, and usually as single inhibitors, or with inhibitor concentrations much higher than those found in lignocellulose hydrolysates. However, the relevance of individual inhibitors in inhibitor-rich lignocellulose hydrolysates has remained unclear. RESULTS: The relative importance for inhibition of ethanol fermentation by two industrial second-generation yeast strains in five lignocellulose hydrolysates, from bagasse, corn cobs and spruce, has now been investigated by spiking higher concentrations of each compound in a concentration range relevant for industrial hydrolysates. The strongest inhibition was observed with industrially relevant concentrations of furfural causing partial inhibition of both D-glucose and D-xylose consumption. Addition of 3 or 6 g/L furfural strongly reduced the ethanol titer obtained with strain MD4 in all hydrolysates evaluated, in a range of 34 to 51% and of 77 to 86%, respectively. This was followed by 5-hydroxymethylfurfural, acetic acid and formic acid, for which in general, industrially relevant concentrations caused partial inhibition of D-xylose fermentation. On the other hand, spiking with levulinic acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid or vanillin caused little inhibition compared to unspiked hydrolysate. The further evolved MD4 strain generally showed superior performance compared to the previously developed strain GSE16-T18. CONCLUSION: The results highlight the importance of individual inhibitor evaluation in a medium containing a genuine mix of inhibitors as well as the ethanol that is produced by the fermentation. They also highlight the potential of increasing yeast inhibitor tolerance for improving industrial process economics. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13068-021-01935-9. |
format | Online Article Text |
id | pubmed-8034183 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-80341832021-04-12 Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates Vanmarcke, Gert Demeke, Mekonnen M. Foulquié-Moreno, Maria R. Thevelein, Johan M. Biotechnol Biofuels Research BACKGROUND: Presence of inhibitory chemicals in lignocellulose hydrolysates is a major hurdle for production of second-generation bioethanol. Especially cheaper pre-treatment methods that ensure an economical viable production process generate high levels of these inhibitory chemicals. The effect of several of these inhibitors has been extensively studied with non-xylose-fermenting laboratory strains, in synthetic media, and usually as single inhibitors, or with inhibitor concentrations much higher than those found in lignocellulose hydrolysates. However, the relevance of individual inhibitors in inhibitor-rich lignocellulose hydrolysates has remained unclear. RESULTS: The relative importance for inhibition of ethanol fermentation by two industrial second-generation yeast strains in five lignocellulose hydrolysates, from bagasse, corn cobs and spruce, has now been investigated by spiking higher concentrations of each compound in a concentration range relevant for industrial hydrolysates. The strongest inhibition was observed with industrially relevant concentrations of furfural causing partial inhibition of both D-glucose and D-xylose consumption. Addition of 3 or 6 g/L furfural strongly reduced the ethanol titer obtained with strain MD4 in all hydrolysates evaluated, in a range of 34 to 51% and of 77 to 86%, respectively. This was followed by 5-hydroxymethylfurfural, acetic acid and formic acid, for which in general, industrially relevant concentrations caused partial inhibition of D-xylose fermentation. On the other hand, spiking with levulinic acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid or vanillin caused little inhibition compared to unspiked hydrolysate. The further evolved MD4 strain generally showed superior performance compared to the previously developed strain GSE16-T18. CONCLUSION: The results highlight the importance of individual inhibitor evaluation in a medium containing a genuine mix of inhibitors as well as the ethanol that is produced by the fermentation. They also highlight the potential of increasing yeast inhibitor tolerance for improving industrial process economics. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13068-021-01935-9. BioMed Central 2021-04-09 /pmc/articles/PMC8034183/ /pubmed/33836811 http://dx.doi.org/10.1186/s13068-021-01935-9 Text en © The Author(s) 2021 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data. |
spellingShingle | Research Vanmarcke, Gert Demeke, Mekonnen M. Foulquié-Moreno, Maria R. Thevelein, Johan M. Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates |
title | Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates |
title_full | Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates |
title_fullStr | Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates |
title_full_unstemmed | Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates |
title_short | Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates |
title_sort | identification of the major fermentation inhibitors of recombinant 2g yeasts in diverse lignocellulose hydrolysates |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8034183/ https://www.ncbi.nlm.nih.gov/pubmed/33836811 http://dx.doi.org/10.1186/s13068-021-01935-9 |
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