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Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors

BACKGROUND: C5–C8 medium-chain carboxylic acids are valuable chemicals as the precursors of various chemicals and transport fuels. However, only a few strict anaerobes have been discovered to produce them and their production is limited to low concentrations because of product toxicity. Therefore, a...

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Autores principales: Jeon, Byoung Seung, Choi, Okkyoung, Um, Youngsoon, Sang, Byoung-In
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918077/
https://www.ncbi.nlm.nih.gov/pubmed/27340431
http://dx.doi.org/10.1186/s13068-016-0549-3
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author Jeon, Byoung Seung
Choi, Okkyoung
Um, Youngsoon
Sang, Byoung-In
author_facet Jeon, Byoung Seung
Choi, Okkyoung
Um, Youngsoon
Sang, Byoung-In
author_sort Jeon, Byoung Seung
collection PubMed
description BACKGROUND: C5–C8 medium-chain carboxylic acids are valuable chemicals as the precursors of various chemicals and transport fuels. However, only a few strict anaerobes have been discovered to produce them and their production is limited to low concentrations because of product toxicity. Therefore, a bacterial strain capable of producing high-titer C5–C8 carboxylic acids was strategically isolated and characterized for production of medium chain length carboxylic acids. RESULTS: Hexanoic acid-producing anaerobes were isolated from the inner surface of a cattle rumen sample. One of the isolates, displaying the highest hexanoic acid production, was identified as Megasphaera sp. MH according to 16S rRNA gene sequence analysis. Megasphaera sp. MH metabolizes fructose and produces various medium-chain carboxylic acids, including hexanoic acid, in low concentrations. The addition of acetate to the fructose medium as an electron acceptor increased hexanoic acid production as well as cell growth. Supplementation of propionate and butyrate into the medium also enhanced the production of C5–C8 medium-chain carboxylic acids. Megasphaera sp. MH produced 5.7 g L(−1) of pentanoic acid (C5), 9.7 g L(−1) of hexanoic acid (C6), 3.2 g L(−1) of heptanoic acid (C7) and 1.2 g L(−1) of octanoic acid (C8) in medium supplemented with C2–C6 carboxylic acids as the electron acceptors. This is the first report on the production of high-titer heptanoic acid and octanoic acid using a pure anaerobic culture. CONCLUSION: Megasphaera sp. MH metabolized fructose for the production of C2–C8 carbon-chain carboxylic acids using various electron acceptors and achieved a high-titer of 9.7 g L(−1) and fast productivity of 0.41 g L(−1) h(−1) for hexanoic acid. However, further metabolic activities of Megaspahera sp. MH for C5–C8 carboxylic acids production must be deciphered and improved for industrially relevant production levels. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-016-0549-3) contains supplementary material, which is available to authorized users.
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spelling pubmed-49180772016-06-24 Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors Jeon, Byoung Seung Choi, Okkyoung Um, Youngsoon Sang, Byoung-In Biotechnol Biofuels Research BACKGROUND: C5–C8 medium-chain carboxylic acids are valuable chemicals as the precursors of various chemicals and transport fuels. However, only a few strict anaerobes have been discovered to produce them and their production is limited to low concentrations because of product toxicity. Therefore, a bacterial strain capable of producing high-titer C5–C8 carboxylic acids was strategically isolated and characterized for production of medium chain length carboxylic acids. RESULTS: Hexanoic acid-producing anaerobes were isolated from the inner surface of a cattle rumen sample. One of the isolates, displaying the highest hexanoic acid production, was identified as Megasphaera sp. MH according to 16S rRNA gene sequence analysis. Megasphaera sp. MH metabolizes fructose and produces various medium-chain carboxylic acids, including hexanoic acid, in low concentrations. The addition of acetate to the fructose medium as an electron acceptor increased hexanoic acid production as well as cell growth. Supplementation of propionate and butyrate into the medium also enhanced the production of C5–C8 medium-chain carboxylic acids. Megasphaera sp. MH produced 5.7 g L(−1) of pentanoic acid (C5), 9.7 g L(−1) of hexanoic acid (C6), 3.2 g L(−1) of heptanoic acid (C7) and 1.2 g L(−1) of octanoic acid (C8) in medium supplemented with C2–C6 carboxylic acids as the electron acceptors. This is the first report on the production of high-titer heptanoic acid and octanoic acid using a pure anaerobic culture. CONCLUSION: Megasphaera sp. MH metabolized fructose for the production of C2–C8 carbon-chain carboxylic acids using various electron acceptors and achieved a high-titer of 9.7 g L(−1) and fast productivity of 0.41 g L(−1) h(−1) for hexanoic acid. However, further metabolic activities of Megaspahera sp. MH for C5–C8 carboxylic acids production must be deciphered and improved for industrially relevant production levels. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-016-0549-3) contains supplementary material, which is available to authorized users. BioMed Central 2016-06-22 /pmc/articles/PMC4918077/ /pubmed/27340431 http://dx.doi.org/10.1186/s13068-016-0549-3 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
Jeon, Byoung Seung
Choi, Okkyoung
Um, Youngsoon
Sang, Byoung-In
Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors
title Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors
title_full Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors
title_fullStr Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors
title_full_unstemmed Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors
title_short Production of medium-chain carboxylic acids by Megasphaera sp. MH with supplemental electron acceptors
title_sort production of medium-chain carboxylic acids by megasphaera sp. mh with supplemental electron acceptors
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918077/
https://www.ncbi.nlm.nih.gov/pubmed/27340431
http://dx.doi.org/10.1186/s13068-016-0549-3
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