Main and interaction effects of acetic acid, furfural, andp-hydroxybenzoic acid on growth and ethanol productivity of yeasts

Palmqvist, Eva; Grage, Halfdan; Meinander, Nina Q.; Hahn-H�gerdal, B.

doi:10.1002/(sici)1097-0290(19990405)63:1<46::aid-bit5>3.0.co;2-j

Cited by 365 publications

(98 citation statements)

References 27 publications

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“…This would be of direct relevance to the application of S. cerevisiae for the production of fuels and chemicals from lignocellulosic hydrolysates. These feedstocks contain complex mixtures of sugars (including galactose) but also high concentrations of acetic acid and other weak organic acids (Klinke et al, 2002;Palmqvist et al, 1999;Rabelo et al, 2008;Sun & Cheng, 2002). Research into the energetic aspects of metabolic flexibility and strategies to buffer cellular energy status [e.g.…”

Section: Discussionmentioning

confidence: 99%

Energetic limits to metabolic flexibility: responses of Saccharomyces cerevisiae to glucose–galactose transitions

et al. 2009

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Glucose is the favoured carbon source for Saccharomyces cerevisiae, and the Leloir pathway for galactose utilization is only induced in the presence of galactose during glucose-derepressed conditions. The goal of this study was to investigate the dynamics of glucose-galactose transitions. To this end, well-controlled, glucose-limited chemostat cultures were switched to galactose-excess conditions. Surprisingly, galactose was not consumed upon a switch to galactose excess under anaerobic conditions. However, the transcripts of the Leloir pathway were highly increased upon galactose excess under both aerobic and anaerobic conditions. Protein and enzyme-activity assays showed that impaired galactose consumption under anaerobiosis coincided with the absence of the Leloir-pathway proteins. Further results showed that absence of protein synthesis was not caused by glucose-mediated translation inhibition. Analysis of adenosine nucleotide pools revealed a fast decrease of the energy charge after the switch from glucose to galactose under anaerobic conditions. Similar results were obtained when glucosegalactose transitions were analysed under aerobic conditions with a respiratory-deficient strain. It is concluded that under fermentative conditions, the energy charge was too low to allow synthesis of the Leloir proteins. Hence, this study conclusively shows that the intracellular energy status is an important factor in the metabolic flexibility of S. cerevisiae upon changes in its environment. INTRODUCTIONGlucose and fructose are preferred sugars for Saccharomyces cerevisiae. Apparently, evolution of this yeast in natural environments that are rich in these sugars (e.g. fruit and nectar) has led to a complicated, multilayered regulatory programme that only enables metabolism of alternative carbon sources (e.g. maltose, ethanol and galactose) when these preferred carbon sources are dwindling.In the case of galactose, a four-enzyme metabolic route, the Leloir pathway, has to be expressed to enable its catabolism. The structural genes for galactose permease (GAL2), galactokinase (GAL1), galactose-1-phosphate uridylyltransferase (GAL7) and uridine-diphosphoglucose 4-epimerase (GAL10) all belong to the GAL regulon, which is subject to tight transcriptional regulation. Glucose causes a nearly complete transcriptional repression of the GAL genes, mediated by the non-phosphorylated form of Mig1, and thereby effectively shuts down galactose utilization (Johnston et al., 1994). Induction of the GAL genes is initiated by interaction of galactose and ATP with Gal3, which then forms a complex with the negative regulator Gal80 (Platt & Reece, 1998). This releases the positive transcriptional regulator Gal4 from Gal80 control and allows it to activate transcription of the GAL1, GAL2, GAL7 and GAL10 genes, which contain upstream activation sequences (UAS GAL ) in their promoter regions (Leuther & Johnston, 1992; Wu et al., 1996). Consequently, S. cerevisiae cells grown in batch cultures on glucose/galactose mixtures show diauxic utilizat...

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Section: Discussionmentioning

confidence: 99%

Energetic limits to metabolic flexibility: responses of Saccharomyces cerevisiae to glucose–galactose transitions

et al. 2009

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“…The concentrations of acetic acid were relatively low, which had no significant effect on the pH. Although acetic acid, which had a concentration range of 100 mM to 170 mM, was more inhibitory to ethanol production by yeast than lactic acid, low concentrations of acetic acid stimulated the ethanol production rate by the yeast (Taherzadeh et al 1997;Palmqvist et al 1999;Pampulha and Loureiro-Dias 2000;Thomas et al 2002;Garay-Arroyo et al 2004).…”

Section: Effect Of Tsc Dosage On Byproducts During Ssf Processmentioning

confidence: 98%

Enhancement of Bioethanol Production Using a Blend of Furfural Production Residue and Tea-seed Cake

Zheng¹,

Xing²,

Zhou³

et al. 2016

BioResources

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The price of raw material, energy demand in the pretreatment step, and enzyme usage rate are the major cost factors in the process of converting biomass to bioethanol. Unwashed furfural residues (FRs) possess great potential for application in bioethanol production. Surfactant addition is an effective method to enhance the fermentation rate. In this study, unwashed FRs were used directly as raw materials to produce bioethanol. Tea-seed cake (TSC), tea seed residues that contained protein and saponin, was added in the simultaneous saccharification and fermentation (SSF) process. The effect of TSC dosage on SSF was compared. TSC was added at the dosage of 10 g/L, which resulted in a final ethanol yield of 87.2%. However, a high concentration of TSC could induce cytotoxicity in yeast. The surface tension (approximately 33.92 mM/m) at SSF using TSC-medium was much lower than that of other fermentation systems (about 64.67 mN/m). Further contact angle testing showed that TSC-medium (21.7°) had better wetting capacity than FRs (45.6°). This study provided a proposed process strategy that SSF with the addition of TSC could be a minimum consumption of chemicals and enzymes for future cellulosic ethanol production process.

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“…Undissociated weak acid was liposoluble and diffused into cells across the plasma membrane (Palmqvist and Hahn-Hägerdal 2000). Acetic acid could then dissociate due to the neutral intracellular pH, decreasing the intracellular pH (Palmqvist et al 1999). A decrease in intracellular pH could cause cell death (Jönsson et al 2013).…”

Section: Itaconic Acid Production From the Undetoxified Enzymatic Hydmentioning

confidence: 99%

Improved Itaconic Acid Production from Undetoxified Enzymatic Hydrolysate of Steam-Exploded Corn Stover using an Aspergillus terreus Mutant Generated by Atmospheric and Room Temperature Plasma

Li¹,

Zheng²,

Lai³

et al. 2016

BioResources

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Itaconic acid production by Aspergillus terreus (A. terreus) was investigated using the undetoxified enzymatic hydrolysate of steamexploded corn stover as the sole carbon source. The fermentation conditions for A. terreus were optimized based on glucose as the carbon source. Unfortunately, wild-type A. terreus did not grow in the undetoxified enzymatic hydrolysate. Therefore, atmospheric and room temperature plasma (ARTP) mutagenesis was applied to obtain A. terreus mutant AT-90. A. terreus mutant AT-90 grew and secreted itaconic acid in the undetoxified enzymatic hydrolysate. The highest itaconic acid concentration (19.30 g/L) with a yield of 36.01% was obtained from the undetoxified enzymatic hydrolysate of 10% (w/v) steam-exploded corn stover. This work demonstrated that the A. terreus mutant generated by ARTP efficiently improved itaconic acid production from lignocellulosebased carbon source.

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Main and interaction effects of acetic acid, furfural, andp-hydroxybenzoic acid on growth and ethanol productivity of yeasts

Cited by 365 publications

References 27 publications

Energetic limits to metabolic flexibility: responses of Saccharomyces cerevisiae to glucose–galactose transitions

Energetic limits to metabolic flexibility: responses of Saccharomyces cerevisiae to glucose–galactose transitions

Enhancement of Bioethanol Production Using a Blend of Furfural Production Residue and Tea-seed Cake

Improved Itaconic Acid Production from Undetoxified Enzymatic Hydrolysate of Steam-Exploded Corn Stover using an Aspergillus terreus Mutant Generated by Atmospheric and Room Temperature Plasma

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