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Expression of Mitochondrial Cytochrome C Oxidase Chaperone Gene (COX20) Improves Tolerance to Weak Acid and Oxidative Stress during Yeast Fermentation.

Kumar V, Hart AJ, Keerthiraju ER, Waldron PR, Tucker GA, Greetham D - PLoS ONE (2015)

Bottom Line: Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol.Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid.This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress.

View Article: PubMed Central - PubMed

Affiliation: University of Nottingham, School of Biosciences, Sutton Bonington Campus, Loughborough, LE12 5RD, United Kingdom.

ABSTRACT

Introduction: Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol. Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid.

Results: A Δcox20 strain was sensitive to the presence of acetic acid compared with the background strain. Overexpressing COX20 using a tetracycline-regulatable expression vector system in a Δcox20 strain, resulted in tolerance to the presence of acetic acid and tolerance could be ablated with addition of tetracycline. Assays also revealed that overexpression improved tolerance to the presence of hydrogen peroxide-induced oxidative stress.

Conclusion: This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress.

No MeSH data available.


Related in: MedlinePlus

Metabolic activity (redox signal intensity) of WT, Δcox20, Δcox20 pCM173, and pCM173(COX20) on hydrolysates derived from an acid pre-treatment of wheat.Results presented are a representative of triplicate values (Mean +/- SD n = 3).
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pone.0139129.g007: Metabolic activity (redox signal intensity) of WT, Δcox20, Δcox20 pCM173, and pCM173(COX20) on hydrolysates derived from an acid pre-treatment of wheat.Results presented are a representative of triplicate values (Mean +/- SD n = 3).

Mentions: We assessed for the importance of overexpressing COX20 when utilising hydrolysates derived from the acid pre-treatment of wheat, hydrolysates with glucose added were assessed using a phenotypic microarray assay. It was observed that there was an improvement in metabolic output in a strain expressing COX20 when compared with the empty vector control (Fig 7), however, when comparing a strain expressing COX20 with the basal wild-type strain there was an initial improvement but that improvement was soon lost and the wild-type strain eventually outperforms the strain which overexpresses COX20 (Fig 7). These strains overexpress COX20 using a tryptophan auxotrophy as a selection requirement, these hydrolysates do contain tryptophan (data not shown) so the selection pressure for maintain strains containing the vector would be lost. This was proven in growth studies on SD-trp which after growth on hydrolysates there was no growth observed indicating a loss of vector in the system.


Expression of Mitochondrial Cytochrome C Oxidase Chaperone Gene (COX20) Improves Tolerance to Weak Acid and Oxidative Stress during Yeast Fermentation.

Kumar V, Hart AJ, Keerthiraju ER, Waldron PR, Tucker GA, Greetham D - PLoS ONE (2015)

Metabolic activity (redox signal intensity) of WT, Δcox20, Δcox20 pCM173, and pCM173(COX20) on hydrolysates derived from an acid pre-treatment of wheat.Results presented are a representative of triplicate values (Mean +/- SD n = 3).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591339&req=5

pone.0139129.g007: Metabolic activity (redox signal intensity) of WT, Δcox20, Δcox20 pCM173, and pCM173(COX20) on hydrolysates derived from an acid pre-treatment of wheat.Results presented are a representative of triplicate values (Mean +/- SD n = 3).
Mentions: We assessed for the importance of overexpressing COX20 when utilising hydrolysates derived from the acid pre-treatment of wheat, hydrolysates with glucose added were assessed using a phenotypic microarray assay. It was observed that there was an improvement in metabolic output in a strain expressing COX20 when compared with the empty vector control (Fig 7), however, when comparing a strain expressing COX20 with the basal wild-type strain there was an initial improvement but that improvement was soon lost and the wild-type strain eventually outperforms the strain which overexpresses COX20 (Fig 7). These strains overexpress COX20 using a tryptophan auxotrophy as a selection requirement, these hydrolysates do contain tryptophan (data not shown) so the selection pressure for maintain strains containing the vector would be lost. This was proven in growth studies on SD-trp which after growth on hydrolysates there was no growth observed indicating a loss of vector in the system.

Bottom Line: Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol.Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid.This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress.

View Article: PubMed Central - PubMed

Affiliation: University of Nottingham, School of Biosciences, Sutton Bonington Campus, Loughborough, LE12 5RD, United Kingdom.

ABSTRACT

Introduction: Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol. Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid.

Results: A Δcox20 strain was sensitive to the presence of acetic acid compared with the background strain. Overexpressing COX20 using a tetracycline-regulatable expression vector system in a Δcox20 strain, resulted in tolerance to the presence of acetic acid and tolerance could be ablated with addition of tetracycline. Assays also revealed that overexpression improved tolerance to the presence of hydrogen peroxide-induced oxidative stress.

Conclusion: This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress.

No MeSH data available.


Related in: MedlinePlus