Proline as a Formic Acid Stress Protectant during Fermentation of Glucose to Ethanol by Saccharomyces spp.

Cyprian E. Oshoma, Trevor G. Phister, Chris D. Powell, Katherine A. Smart, Chenyu Du

Research output: Contribution to journalArticle

Abstract

During bioethanol production from lignocellulosic hydrolysates, yeasts are frequently exposed to various forms of fermentation stress. These include nutritional starvation, metabolites production, and fermentation-inhibiting compounds produced during pretreatment and hydrolysis of the lignocellulosic material. These inhibitors hamper efficient ethanol production as they can be toxic to the microbes conducting the fermentation. Formic acid is a significant inhibitor released into the hydrolyzates at a concentration of 10-30 mM. Previously it was found that proline acts as a compatible solute that enhances yeast tolerance to stress and therefore improves fermentation efficiency. Proline functions in vitro in protein and membrane stabilization, lowering Tm of DNA and scavenging of reactive oxygen species. In this study, the addition of proline to the media in order to improve the tolerance of yeast to formic acid during fermentation was investigated using Saccharomyces cerevisiae NCYC2592 and Saccharomyces arboricolus 2.3319. It was observed that when proline was present at 30 mM in the medium, cell growth was enhanced compared to the control medium in fermentations using both S. cerevisiae NCYC2592 and S. arboricolus 2.3319. The cell number obtained in proline-supplemented medium increased by 8-10% for both S. cerevisiae NCYC2592 and S. arboricolus 2.3319. Cells cultivated on proline medium yielded a higher accumulation of ethanol than the control medium in both strains. These results indicate that modification of growth medium with proline can increase formic acid tolerance and the fermentative ability of yeast cells.

Original languageEnglish
Pages (from-to)209-216
Number of pages8
JournalIndustrial Biotechnology
Volume13
Issue number4
DOIs
Publication statusPublished - 1 Aug 2017

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formic acid
Saccharomyces
Proline
Fermentation
Ethanol
Glucose
Yeasts
Saccharomyces cerevisiae
Poisons
Growth
Starvation

Cite this

Oshoma, Cyprian E. ; Phister, Trevor G. ; Powell, Chris D. ; Smart, Katherine A. ; Du, Chenyu. / Proline as a Formic Acid Stress Protectant during Fermentation of Glucose to Ethanol by Saccharomyces spp. In: Industrial Biotechnology. 2017 ; Vol. 13, No. 4. pp. 209-216.
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abstract = "During bioethanol production from lignocellulosic hydrolysates, yeasts are frequently exposed to various forms of fermentation stress. These include nutritional starvation, metabolites production, and fermentation-inhibiting compounds produced during pretreatment and hydrolysis of the lignocellulosic material. These inhibitors hamper efficient ethanol production as they can be toxic to the microbes conducting the fermentation. Formic acid is a significant inhibitor released into the hydrolyzates at a concentration of 10-30 mM. Previously it was found that proline acts as a compatible solute that enhances yeast tolerance to stress and therefore improves fermentation efficiency. Proline functions in vitro in protein and membrane stabilization, lowering Tm of DNA and scavenging of reactive oxygen species. In this study, the addition of proline to the media in order to improve the tolerance of yeast to formic acid during fermentation was investigated using Saccharomyces cerevisiae NCYC2592 and Saccharomyces arboricolus 2.3319. It was observed that when proline was present at 30 mM in the medium, cell growth was enhanced compared to the control medium in fermentations using both S. cerevisiae NCYC2592 and S. arboricolus 2.3319. The cell number obtained in proline-supplemented medium increased by 8-10{\%} for both S. cerevisiae NCYC2592 and S. arboricolus 2.3319. Cells cultivated on proline medium yielded a higher accumulation of ethanol than the control medium in both strains. These results indicate that modification of growth medium with proline can increase formic acid tolerance and the fermentative ability of yeast cells.",
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Proline as a Formic Acid Stress Protectant during Fermentation of Glucose to Ethanol by Saccharomyces spp. / Oshoma, Cyprian E.; Phister, Trevor G.; Powell, Chris D.; Smart, Katherine A.; Du, Chenyu.

In: Industrial Biotechnology, Vol. 13, No. 4, 01.08.2017, p. 209-216.

Research output: Contribution to journalArticle

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T1 - Proline as a Formic Acid Stress Protectant during Fermentation of Glucose to Ethanol by Saccharomyces spp.

AU - Oshoma, Cyprian E.

AU - Phister, Trevor G.

AU - Powell, Chris D.

AU - Smart, Katherine A.

AU - Du, Chenyu

PY - 2017/8/1

Y1 - 2017/8/1

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AB - During bioethanol production from lignocellulosic hydrolysates, yeasts are frequently exposed to various forms of fermentation stress. These include nutritional starvation, metabolites production, and fermentation-inhibiting compounds produced during pretreatment and hydrolysis of the lignocellulosic material. These inhibitors hamper efficient ethanol production as they can be toxic to the microbes conducting the fermentation. Formic acid is a significant inhibitor released into the hydrolyzates at a concentration of 10-30 mM. Previously it was found that proline acts as a compatible solute that enhances yeast tolerance to stress and therefore improves fermentation efficiency. Proline functions in vitro in protein and membrane stabilization, lowering Tm of DNA and scavenging of reactive oxygen species. In this study, the addition of proline to the media in order to improve the tolerance of yeast to formic acid during fermentation was investigated using Saccharomyces cerevisiae NCYC2592 and Saccharomyces arboricolus 2.3319. It was observed that when proline was present at 30 mM in the medium, cell growth was enhanced compared to the control medium in fermentations using both S. cerevisiae NCYC2592 and S. arboricolus 2.3319. The cell number obtained in proline-supplemented medium increased by 8-10% for both S. cerevisiae NCYC2592 and S. arboricolus 2.3319. Cells cultivated on proline medium yielded a higher accumulation of ethanol than the control medium in both strains. These results indicate that modification of growth medium with proline can increase formic acid tolerance and the fermentative ability of yeast cells.

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KW - Formic Acid Stress

KW - Lignocellulosic Biofuel

KW - Proline

KW - Saccharomyces Arboricolus

KW - Saccharomyces Cerevisiae

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M3 - Article

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EP - 216

JO - Industrial Biotechnology

JF - Industrial Biotechnology

SN - 1550-9087

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