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Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols
Chain elongation fermentation allows for the synthesis of biobased chemicals from complex organic residue streams. To expand the product spectrum of chain elongation technology and its application range we investigated 1) how to increase selectivity towards branched chain elongation and 2) whether a...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Frontiers Media S.A.
2021
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8416115/ https://www.ncbi.nlm.nih.gov/pubmed/34485254 http://dx.doi.org/10.3389/fbioe.2021.697439 |
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author | de Leeuw, Kasper D. Ahrens, Theresa Buisman, Cees J. N. Strik, David P. B. T. B. |
author_facet | de Leeuw, Kasper D. Ahrens, Theresa Buisman, Cees J. N. Strik, David P. B. T. B. |
author_sort | de Leeuw, Kasper D. |
collection | PubMed |
description | Chain elongation fermentation allows for the synthesis of biobased chemicals from complex organic residue streams. To expand the product spectrum of chain elongation technology and its application range we investigated 1) how to increase selectivity towards branched chain elongation and 2) whether alternative branched carboxylates such as branched valerates can be used as electron acceptors. Elongation of isobutyrate elongation towards 4-methyl-pentanoate was achieved with a selectivity of 27% (of total products, based on carbon atoms) in a continuous system that operated under CO(2) and acetate limited conditions. Increasing the CO(2) load led to more in situ acetate formation that increased overall chain elongation rate but decreased the selectivity of branched chain elongation. A part of this acetate formation was related to direct ethanol oxidation that seemed to be thermodynamically coupled to hydrogenotrophic carboxylate reduction to corresponding alcohols. Several alcohols including isobutanol and n-hexanol were formed. The microbiome from the continuous reactor was also able to form small amounts of 5-methyl-hexanoate likely from 3-methyl-butanoate and ethanol as substrate in batch experiments. The highest achieved concentration of isoheptanoate was 6.4 ± 0.9 mM Carbon, or 118 ± 17 mg/L, which contributed for 7% to the total amount of products (based on carbon atoms). The formation of isoheptanoate was dependent on the isoform of branched valerate. With 3-methyl-butanoate as substrate 5-methylhexanoate was formed, whereas a racemic mixture of L/D 2-methyl-butanoate did not lead to an elongated product. When isobutyrate and isovalerate were added simultaneously as substrates there was a large preference for elongation of isobutyrate over isovalerate. Overall, this work showed that chain elongation microbiomes can be further adapted with supplement of branched-electron acceptors towards the formation of iso-caproate and iso-heptanoate as well as that longer chain alcohol formation can be stimulated. |
format | Online Article Text |
id | pubmed-8416115 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-84161152021-09-04 Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols de Leeuw, Kasper D. Ahrens, Theresa Buisman, Cees J. N. Strik, David P. B. T. B. Front Bioeng Biotechnol Bioengineering and Biotechnology Chain elongation fermentation allows for the synthesis of biobased chemicals from complex organic residue streams. To expand the product spectrum of chain elongation technology and its application range we investigated 1) how to increase selectivity towards branched chain elongation and 2) whether alternative branched carboxylates such as branched valerates can be used as electron acceptors. Elongation of isobutyrate elongation towards 4-methyl-pentanoate was achieved with a selectivity of 27% (of total products, based on carbon atoms) in a continuous system that operated under CO(2) and acetate limited conditions. Increasing the CO(2) load led to more in situ acetate formation that increased overall chain elongation rate but decreased the selectivity of branched chain elongation. A part of this acetate formation was related to direct ethanol oxidation that seemed to be thermodynamically coupled to hydrogenotrophic carboxylate reduction to corresponding alcohols. Several alcohols including isobutanol and n-hexanol were formed. The microbiome from the continuous reactor was also able to form small amounts of 5-methyl-hexanoate likely from 3-methyl-butanoate and ethanol as substrate in batch experiments. The highest achieved concentration of isoheptanoate was 6.4 ± 0.9 mM Carbon, or 118 ± 17 mg/L, which contributed for 7% to the total amount of products (based on carbon atoms). The formation of isoheptanoate was dependent on the isoform of branched valerate. With 3-methyl-butanoate as substrate 5-methylhexanoate was formed, whereas a racemic mixture of L/D 2-methyl-butanoate did not lead to an elongated product. When isobutyrate and isovalerate were added simultaneously as substrates there was a large preference for elongation of isobutyrate over isovalerate. Overall, this work showed that chain elongation microbiomes can be further adapted with supplement of branched-electron acceptors towards the formation of iso-caproate and iso-heptanoate as well as that longer chain alcohol formation can be stimulated. Frontiers Media S.A. 2021-08-17 /pmc/articles/PMC8416115/ /pubmed/34485254 http://dx.doi.org/10.3389/fbioe.2021.697439 Text en Copyright © 2021 de Leeuw, Ahrens, Buisman and Strik. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Bioengineering and Biotechnology de Leeuw, Kasper D. Ahrens, Theresa Buisman, Cees J. N. Strik, David P. B. T. B. Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols |
title | Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols |
title_full | Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols |
title_fullStr | Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols |
title_full_unstemmed | Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols |
title_short | Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols |
title_sort | open culture ethanol-based chain elongation to form medium chain branched carboxylates and alcohols |
topic | Bioengineering and Biotechnology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8416115/ https://www.ncbi.nlm.nih.gov/pubmed/34485254 http://dx.doi.org/10.3389/fbioe.2021.697439 |
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