Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations

Continuous removal of ethanol during production by the anaerobic bacterium Zymomonas mobilis mitigated ethanol inhibition. Ethanol inhibited its own production at a concentration of >20 g L−1. Ethanol productivity was enhanced by continuous in situ extraction with water-immiscible organic solvent...

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Main Authors: Azilah, Ajit, Ahmad Ziad, Sulaiman, Chisti, Yusuf
Format: Article
Published: Elsevier Ltd 2017
Subjects:
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author Azilah, Ajit
Ahmad Ziad, Sulaiman
Chisti, Yusuf
author_facet Azilah, Ajit
Ahmad Ziad, Sulaiman
Chisti, Yusuf
author_sort Azilah, Ajit
collection UMP
description Continuous removal of ethanol during production by the anaerobic bacterium Zymomonas mobilis mitigated ethanol inhibition. Ethanol inhibited its own production at a concentration of >20 g L−1. Ethanol productivity was enhanced by continuous in situ extraction with water-immiscible organic solvents. Several solvents were evaluated for biocompatibility with Z. mobilis and the ability to extract ethanol from a batch fermentation. In situ batch extractive fermentations were carried out in a 2-L stirred bioreactor (1:1 volume ratio of solvent and fermentation broth) with an optimal glucose concentration of 150 g L−1, 35 °C, and an agitation speed of 150 rpm. Oleyl alcohol, iso-octadecanol and 2-octyl-1-dodecanol were the three solvents that were most compatible with Z. mobilis. With these solvents, the cell viability relative to control (no solvent) was 1.48 ± 0.40, 1.03 ± 0.18 and 1.05 ± 0.07, respectively, after two days of exposure. All solvents tested improved the final biomass concentration, the glucose consumption and ethanol production relative to control, but iso-octadecanol was clearly the most effective solvent. Using iso-octadecanol, the maximum ethanol concentration of 75 ± 3 g L−1 was attained. This was nearly 1.25-fold that of the control fermentation. For this solvent, the ethanol yield on glucose was 0.485 ± 0.005 g g−1 compared to a yield of 0.468 ± 0.005 g g−1 for the control culture.
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spelling UMPir164502018-01-30T02:58:34Z http://umpir.ump.edu.my/id/eprint/16450/ Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations Azilah, Ajit Ahmad Ziad, Sulaiman Chisti, Yusuf TP Chemical technology Continuous removal of ethanol during production by the anaerobic bacterium Zymomonas mobilis mitigated ethanol inhibition. Ethanol inhibited its own production at a concentration of >20 g L−1. Ethanol productivity was enhanced by continuous in situ extraction with water-immiscible organic solvents. Several solvents were evaluated for biocompatibility with Z. mobilis and the ability to extract ethanol from a batch fermentation. In situ batch extractive fermentations were carried out in a 2-L stirred bioreactor (1:1 volume ratio of solvent and fermentation broth) with an optimal glucose concentration of 150 g L−1, 35 °C, and an agitation speed of 150 rpm. Oleyl alcohol, iso-octadecanol and 2-octyl-1-dodecanol were the three solvents that were most compatible with Z. mobilis. With these solvents, the cell viability relative to control (no solvent) was 1.48 ± 0.40, 1.03 ± 0.18 and 1.05 ± 0.07, respectively, after two days of exposure. All solvents tested improved the final biomass concentration, the glucose consumption and ethanol production relative to control, but iso-octadecanol was clearly the most effective solvent. Using iso-octadecanol, the maximum ethanol concentration of 75 ± 3 g L−1 was attained. This was nearly 1.25-fold that of the control fermentation. For this solvent, the ethanol yield on glucose was 0.485 ± 0.005 g g−1 compared to a yield of 0.468 ± 0.005 g g−1 for the control culture. Elsevier Ltd 2017 Article PeerReviewed Azilah, Ajit and Ahmad Ziad, Sulaiman and Chisti, Yusuf (2017) Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations. Food and Bioproducts Processing, 102. pp. 123-135. ISSN 0960-3085. (Published) http://dx.doi.org/10.1016/j.fbp.2016.12.006 DOI: 10.1016/j.fbp.2016.12.006
spellingShingle TP Chemical technology
Azilah, Ajit
Ahmad Ziad, Sulaiman
Chisti, Yusuf
Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations
title Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations
title_full Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations
title_fullStr Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations
title_full_unstemmed Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations
title_short Production of Bioethanol by Zymomonas Mobilis in High-gravity Extractive Fermentations
title_sort production of bioethanol by zymomonas mobilis in high gravity extractive fermentations
topic TP Chemical technology
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AT ahmadziadsulaiman productionofbioethanolbyzymomonasmobilisinhighgravityextractivefermentations
AT chistiyusuf productionofbioethanolbyzymomonasmobilisinhighgravityextractivefermentations