Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH Control

The sharp rise in the worldwide production of biodiesel has created an excess in the crude glycerol market, so it is essential to develop new added-value alternatives for crude glycerol. This paper describes a study on fermenting high concentrations of two types of medium-pure crude glycerol to solv...

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Main Authors: Alejandro Ortega, Alejo Valles, Miguel Capilla, Carmen Gabaldón, Francisco Javier Álvarez-Hornos, Paula Marzal
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Fermentation
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Online Access:https://www.mdpi.com/2311-5637/11/6/339
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author Alejandro Ortega
Alejo Valles
Miguel Capilla
Carmen Gabaldón
Francisco Javier Álvarez-Hornos
Paula Marzal
author_facet Alejandro Ortega
Alejo Valles
Miguel Capilla
Carmen Gabaldón
Francisco Javier Álvarez-Hornos
Paula Marzal
author_sort Alejandro Ortega
collection DOAJ
description The sharp rise in the worldwide production of biodiesel has created an excess in the crude glycerol market, so it is essential to develop new added-value alternatives for crude glycerol. This paper describes a study on fermenting high concentrations of two types of medium-pure crude glycerol to solvents by <i>Clostridium pasteurianum</i>. The effect of media composition (iron, yeast extract, and vitamins) on solvents production was assessed by a full factorial design with pure glycerol. Granular activated carbon (GAC) adsorption was highly effective in removing impurities from crude glycerol. Following GAC pretreatment, fermentation of glycerol at initial concentration as high as 60 g L<sup>−1</sup> was possible, resulting in a butanol production of ~9 g L<sup>−1</sup>. Based on these results, a batch fermentation with in situ gas stripping and pH controlled at ≥6.5 was shown to be the best alternative to enhance biomass growth, glycerol uptake, and solvent production. The combination of controlling pH in the early stages of fermentation with in situ butanol removal stabilised the metabolism of the strain and showed that the fermentation performance with crude glycerol is very similar to that of pure glycerol. With a notable uptake of glycerol (>83%), solvent production was >11 g L<sup>−1</sup> butanol (yield > 0.21 g g<sup>−1</sup><sub>glycerol consumed</sub>) and >6 g L<sup>−1</sup> 1,3-propanediol (yield > 0.13 g g<sup>−1</sup><sub>glycerol consumed</sub>). Setting the fermentation conditions to achieve a high uptake of high levels of glycerol with a similar product distribution is of great interest for the viability of the industrial processing of crude glycerol into chemicals via biological conversion.
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series Fermentation
spelling doaj-art-e8878a0c4577440b88cff6723adeb6212025-08-20T03:24:33ZengMDPI AGFermentation2311-56372025-06-0111633910.3390/fermentation11060339Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH ControlAlejandro Ortega0Alejo Valles1Miguel Capilla2Carmen Gabaldón3Francisco Javier Álvarez-Hornos4Paula Marzal5Research Group GI2AM, Department of Chemical Engineering, Universitat de València, Av. de la Universitat S/N, 46100 Burjassot, SpainResearch Group GI2AM, Department of Chemical Engineering, Universitat de València, Av. de la Universitat S/N, 46100 Burjassot, SpainResearch Group GI2AM, Department of Chemical Engineering, Universitat de València, Av. de la Universitat S/N, 46100 Burjassot, SpainResearch Group GI2AM, Department of Chemical Engineering, Universitat de València, Av. de la Universitat S/N, 46100 Burjassot, SpainResearch Group GI2AM, Department of Chemical Engineering, Universitat de València, Av. de la Universitat S/N, 46100 Burjassot, SpainResearch Group GI2AM, Department of Chemical Engineering, Universitat de València, Av. de la Universitat S/N, 46100 Burjassot, SpainThe sharp rise in the worldwide production of biodiesel has created an excess in the crude glycerol market, so it is essential to develop new added-value alternatives for crude glycerol. This paper describes a study on fermenting high concentrations of two types of medium-pure crude glycerol to solvents by <i>Clostridium pasteurianum</i>. The effect of media composition (iron, yeast extract, and vitamins) on solvents production was assessed by a full factorial design with pure glycerol. Granular activated carbon (GAC) adsorption was highly effective in removing impurities from crude glycerol. Following GAC pretreatment, fermentation of glycerol at initial concentration as high as 60 g L<sup>−1</sup> was possible, resulting in a butanol production of ~9 g L<sup>−1</sup>. Based on these results, a batch fermentation with in situ gas stripping and pH controlled at ≥6.5 was shown to be the best alternative to enhance biomass growth, glycerol uptake, and solvent production. The combination of controlling pH in the early stages of fermentation with in situ butanol removal stabilised the metabolism of the strain and showed that the fermentation performance with crude glycerol is very similar to that of pure glycerol. With a notable uptake of glycerol (>83%), solvent production was >11 g L<sup>−1</sup> butanol (yield > 0.21 g g<sup>−1</sup><sub>glycerol consumed</sub>) and >6 g L<sup>−1</sup> 1,3-propanediol (yield > 0.13 g g<sup>−1</sup><sub>glycerol consumed</sub>). Setting the fermentation conditions to achieve a high uptake of high levels of glycerol with a similar product distribution is of great interest for the viability of the industrial processing of crude glycerol into chemicals via biological conversion.https://www.mdpi.com/2311-5637/11/6/339activated carbonbutanol<i>Clostridium pasteurianum</i>crude glycerolgas stripping1,3-propanediol
spellingShingle Alejandro Ortega
Alejo Valles
Miguel Capilla
Carmen Gabaldón
Francisco Javier Álvarez-Hornos
Paula Marzal
Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH Control
Fermentation
activated carbon
butanol
<i>Clostridium pasteurianum</i>
crude glycerol
gas stripping
1,3-propanediol
title Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH Control
title_full Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH Control
title_fullStr Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH Control
title_full_unstemmed Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH Control
title_short Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH Control
title_sort enhancing bioconversion of crude glycerol into butanol and 1 3 propanediol after pretreatment by coupling fermentation and in situ recovery effect of initial ph control
topic activated carbon
butanol
<i>Clostridium pasteurianum</i>
crude glycerol
gas stripping
1,3-propanediol
url https://www.mdpi.com/2311-5637/11/6/339
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