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Sequential Mixed Cultures: From Syngas to Malic Acid

Synthesis gas (syngas) fermentation using acetogenic bacteria is an approach for production of bulk chemicals like acetate, ethanol, butanol, or 2,3-butandiol avoiding the fuel vs. food debate by using carbon monoxide, carbon dioxide, and hydrogen from gasification of biomass or industrial waste gas...

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Autores principales: Oswald, Florian, Dörsam, Stefan, Veith, Nicolas, Zwick, Michaela, Neumann, Anke, Ochsenreither, Katrin, Syldatk, Christoph
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4914491/
https://www.ncbi.nlm.nih.gov/pubmed/27445993
http://dx.doi.org/10.3389/fmicb.2016.00891
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author Oswald, Florian
Dörsam, Stefan
Veith, Nicolas
Zwick, Michaela
Neumann, Anke
Ochsenreither, Katrin
Syldatk, Christoph
author_facet Oswald, Florian
Dörsam, Stefan
Veith, Nicolas
Zwick, Michaela
Neumann, Anke
Ochsenreither, Katrin
Syldatk, Christoph
author_sort Oswald, Florian
collection PubMed
description Synthesis gas (syngas) fermentation using acetogenic bacteria is an approach for production of bulk chemicals like acetate, ethanol, butanol, or 2,3-butandiol avoiding the fuel vs. food debate by using carbon monoxide, carbon dioxide, and hydrogen from gasification of biomass or industrial waste gases. Suffering from energetic limitations, yields of C(4)-molecules produced by syngas fermentation are quite low compared with ABE fermentation using sugars as a substrate. On the other hand, fungal production of malic acid has high yields of product per gram metabolized substrate but is currently limited to sugar containing substrates. In this study, it was possible to show that Aspergilus oryzae is able to produce malic acid using acetate as sole carbon source which is a main product of acetogenic syngas fermentation. Bioreactor cultivations were conducted in 2.5 L stirred tank reactors. During the syngas fermentation part of the sequential mixed culture, Clostridium ljungdahlii was grown in modified Tanner medium and sparged with 20 mL/min of artificial syngas mimicking a composition of clean syngas from entrained bed gasification of straw (32.5 vol-% CO, 32.5 vol-% H(2), 16 vol-% CO(2), and 19 vol-% N(2)) using a microsparger. Syngas consumption was monitored via automated gas chromatographic measurement of the off-gas. For the fungal fermentation part gas sparging was switched to 0.6 L/min of air and a standard sparger. Ammonia content of medium for syngas fermentation was reduced to 0.33 g/L NH(4)Cl to meet the requirements for fungal production of dicarboxylic acids. Malic acid production performance of A. oryzae in organic acid production medium and syngas medium with acetate as sole carbon source was verified and gave Y(P∕S) values of 0.28 g/g and 0.37 g/g respectively. Growth and acetate formation of C. ljungdahlii during syngas fermentation were not affected by the reduced ammonia content and 66 % of the consumed syngas was converted to acetate. The overall conversion of CO and H(2) into malic acid was calculated to be 3.5 g malic acid per mol of consumed syngas or 0.22 g malic acid per gram of syngas.
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spelling pubmed-49144912016-07-21 Sequential Mixed Cultures: From Syngas to Malic Acid Oswald, Florian Dörsam, Stefan Veith, Nicolas Zwick, Michaela Neumann, Anke Ochsenreither, Katrin Syldatk, Christoph Front Microbiol Microbiology Synthesis gas (syngas) fermentation using acetogenic bacteria is an approach for production of bulk chemicals like acetate, ethanol, butanol, or 2,3-butandiol avoiding the fuel vs. food debate by using carbon monoxide, carbon dioxide, and hydrogen from gasification of biomass or industrial waste gases. Suffering from energetic limitations, yields of C(4)-molecules produced by syngas fermentation are quite low compared with ABE fermentation using sugars as a substrate. On the other hand, fungal production of malic acid has high yields of product per gram metabolized substrate but is currently limited to sugar containing substrates. In this study, it was possible to show that Aspergilus oryzae is able to produce malic acid using acetate as sole carbon source which is a main product of acetogenic syngas fermentation. Bioreactor cultivations were conducted in 2.5 L stirred tank reactors. During the syngas fermentation part of the sequential mixed culture, Clostridium ljungdahlii was grown in modified Tanner medium and sparged with 20 mL/min of artificial syngas mimicking a composition of clean syngas from entrained bed gasification of straw (32.5 vol-% CO, 32.5 vol-% H(2), 16 vol-% CO(2), and 19 vol-% N(2)) using a microsparger. Syngas consumption was monitored via automated gas chromatographic measurement of the off-gas. For the fungal fermentation part gas sparging was switched to 0.6 L/min of air and a standard sparger. Ammonia content of medium for syngas fermentation was reduced to 0.33 g/L NH(4)Cl to meet the requirements for fungal production of dicarboxylic acids. Malic acid production performance of A. oryzae in organic acid production medium and syngas medium with acetate as sole carbon source was verified and gave Y(P∕S) values of 0.28 g/g and 0.37 g/g respectively. Growth and acetate formation of C. ljungdahlii during syngas fermentation were not affected by the reduced ammonia content and 66 % of the consumed syngas was converted to acetate. The overall conversion of CO and H(2) into malic acid was calculated to be 3.5 g malic acid per mol of consumed syngas or 0.22 g malic acid per gram of syngas. Frontiers Media S.A. 2016-06-21 /pmc/articles/PMC4914491/ /pubmed/27445993 http://dx.doi.org/10.3389/fmicb.2016.00891 Text en Copyright © 2016 Oswald, Dörsam, Veith, Zwick, Neumann, Ochsenreither and Syldatk. http://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) or licensor 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 Microbiology
Oswald, Florian
Dörsam, Stefan
Veith, Nicolas
Zwick, Michaela
Neumann, Anke
Ochsenreither, Katrin
Syldatk, Christoph
Sequential Mixed Cultures: From Syngas to Malic Acid
title Sequential Mixed Cultures: From Syngas to Malic Acid
title_full Sequential Mixed Cultures: From Syngas to Malic Acid
title_fullStr Sequential Mixed Cultures: From Syngas to Malic Acid
title_full_unstemmed Sequential Mixed Cultures: From Syngas to Malic Acid
title_short Sequential Mixed Cultures: From Syngas to Malic Acid
title_sort sequential mixed cultures: from syngas to malic acid
topic Microbiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4914491/
https://www.ncbi.nlm.nih.gov/pubmed/27445993
http://dx.doi.org/10.3389/fmicb.2016.00891
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