Furfural, 5‐hydroxymethyl furfural, and acetoin act as external electron acceptors during anaerobic fermentation of xylose in recombinant <i>Saccharomyces cerevisiae</i>

Wahlbom, C. Fredrik; Hahn‐Hägerdal, Bärbel

doi:10.1002/bit.10188

Cited by 168 publications

(45 citation statements)

References 42 publications

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“…This property helps the biological detoxification process to reserve the glucose sugar for the final fermentation of target products such as ethanol, instead of the consumption on degradation of inhibitor compounds; 6) degradation of furfural and HMF by A. resinae ZN1 may have a strong cofactor preference in its metabolic pathways [38,39]. The reduction of HMF is coupled with the oxidation of nicotinamide adenine dinucleotide phosphate (NADPH) [40], whereas NADPH is mainly produced by pentose phosphate pathway and its concentration level is highly associated with glucose [41,27]. Perhaps there is a similar mechanism; the existence of HMF in A. resinae ZN1 enhances the expression of the related genes, such as ZWF1 , GND1 , and GND2 in glucose metabolism of yeast, and then the concentration of NADPH is elevated, thus, the degradation of HMF is increased [27].…”

Section: Resultsmentioning

confidence: 99%

Analysis of biodegradation performance of furfural and 5-hydroxymethylfurfural by Amorphotheca resinae ZN1

Ran

Zhang

Gao

et al. 2014

Biotechnol Biofuels

109

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BackgroundFurfural and 5-hydroxymethylfurfural (HMF) are the degradation products of lignocellulose during pretreatment operations and significantly inhibit the consequent enzymatic hydrolysis and fermentation processes. The biodetoxification fungus Amorphotheca resinae ZN1 had demonstrated its excellent capacity on degrading lignocellulose derived inhibitors and helped the fermentation processes to achieve high yield of ethanol and biochemicals. Analysis of the biological degradation performance of furfural and HMF by A. resinae ZN1 will provide essential information for their fast and complete removal from the pretreated lignocellulose materials and facilitate the consequent ethanol fermentation.ResultsThe degradation performance of furfural and HMF by A. resinae ZN1 was investigated by capturing intermediate metabolic products at various culture conditions. A. resinae ZN1 converts furfural/HMF into furfuryl/HMF alcohols and furoic/HMF acids simultaneously at aerobic condition, and only the corresponding furfuryl/HMF alcohols are obtained at anaerobic condition. The existence of glucose accelerates the degradation rate of furfural and HMF by A. resinae ZN1 and the cell mass growth rate aerobically. Remarkably, glucose is not consumed before furfural or HMF is degraded to a low threshold concentration. The finding suggests that furfural or HMF has a substrate priority of utilization by A. resinae ZN1 than glucose. This property may help the detoxification of furfural and HMF to be operated without consuming glucose.ConclusionsThe biological degradation performance of furfural and HMF by A. resinae ZN1 was investigated experimentally. Oxygen supply is important on the complete biodegradation of furfural and HMF by A. resinae ZN1. Furfural or HMF has the priority of substrate utilization than glucose by A. resinae ZN1. This study provided important information for detoxification enhancement and strain modification.

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Section: Resultsmentioning

confidence: 99%

Analysis of biodegradation performance of furfural and 5-hydroxymethylfurfural by Amorphotheca resinae ZN1

Ran

Zhang

Gao

et al. 2014

Biotechnol Biofuels

109

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“…Various degradation compounds are released from lignocellulose degradation during the pretreatment and will enter the downstream hydrolysis and fermentation processes. These degradation products in the hydrolysate include sugar degradation products such as furfural from xylose and 5-hydroxymethylfurfural (5-HMF) from glucose [9]; lignin degradation products such as vanillin, syringaldehyde, and 4-hydroxybenzaldehyde [10]; organic acids such as acetic acid from acetyl group, formic acid from xylose oxidation, and levulinic acid from glucose oxidation [11]. The composition of the degradation products depends on the type of lignocellulosic materials used, as well as the chemistry and the nature of the pretreatment process.…”

Section: Introductionmentioning

confidence: 99%

Screening of Oleaginous Yeast Strains Tolerant to Lignocellulose Degradation Compounds

Chen

Zhang³

et al. 2009

Appl Biochem Biotechnol

206

105

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High cost of triacylglycerol lipid feedstock is the major barrier for commercial production of biodiesel. The fermentation of oleaginous yeasts for lipid production using lignocellulose biomass provides a practical option with high economic competitiveness. In this paper, the typical oleaginous yeast strains were screened under the pressure of lignocellulose degradation compounds for selection of the optimal strains tolerant to lignocellulose. The inhibitory effect of lignocellulose degradation products on the oleaginous yeast fermentation was carefully investigated. Preliminary screening was carried out in the minimum nutritious medium without adding any expensive complex ingredients then was carried out in the lignocellulosic hydrolysate pretreated by dilute sulfuric acid. Seven typical lignocellulose degradation products formed in various pretreatment and hydrolysis processing were selected as the model inhibitors, including three organic acids, two furan compounds, and two phenol derivatives. The inhibition of the degradation compounds on the cell growth and lipid productivity of the selected oleaginous yeasts were examined. Acetic acid, formic acid, furfural, and vanillin were found to be the strong inhibitors for the fermentation of oleaginous yeasts, while levulinic acid, 5-hydroxymethylfurfural, and hydroxybenzaldehyde were relatively weak inhibitors. Trichosporon cutaneum 2.1374 was found to be the most adopted strain to the lignocellulose degradation compounds.

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“…Therefore, compared to strain D5A +H on xylose as carbon source, the presence of inhibitors appeared to have a less drastic effect on strain TMB3400, possibly attributable to the presence of XR. Furfural was shown to serve as an effective electron acceptor for XR, as evident from decreased xylitol formation, resulting in an improved ethanol yield [42], although no ethanol production by strain TMB3400 on xylose was observed in the present study (Table 3). Furthermore, strain D5A +H exhibited a much shorter lag phase than strain TMB3400, where the lag phase for the latter strain lasted up to 30 h (Figure 2A, C and E).…”

Section: Discussionmentioning

confidence: 60%

“…Simultaneously, selective pressure through xylose as carbon source was imposed during both steps to enhance the metabolism of this pentose sugar via the XI pathway. Xylose isomerase represents the advantage of avoiding co-factor imbalances in the microbial metabolism at low oxygen tension, as opposed to the XR/XDH pathway, where XR was found to prefer NADPH as co-factor [11,24,42]. Furthermore, during evolutionary engineering, Koppram et al .…”

Section: Discussionmentioning

confidence: 99%

Simultaneously improving xylose fermentation and tolerance to lignocellulosic inhibitors through evolutionary engineering of recombinant Saccharomyces cerevisiaeharbouring xylose isomerase

2014

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BackgroundYeasts tolerant to toxic inhibitors from steam-pretreated lignocellulose with xylose co-fermentation capability represent an appealing approach for 2nd generation ethanol production. Whereas rational engineering, mutagenesis and evolutionary engineering are established techniques for either improved xylose utilisation or enhancing yeast tolerance, this report focuses on the simultaneous enhancement of these attributes through mutagenesis and evolutionary engineering of Saccharomyces cerevisiae harbouring xylose isomerase in anoxic chemostat culture using non-detoxified pretreatment liquor from triticale straw.ResultsFollowing ethyl methanesulfonate (EMS) mutagenesis, Saccharomyces cerevisiae strain D5A+ (ATCC 200062 strain platform), harbouring the xylose isomerase (XI) gene for pentose co-fermentation was grown in anoxic chemostat culture for 100 generations at a dilution rate of 0.10 h-1 in a medium consisting of 60% (v/v) non-detoxified hydrolysate liquor from steam-pretreated triticale straw, supplemented with 20 g/L xylose as carbon source. In semi-aerobic batch cultures in the same medium, the isolated strain D5A+H exhibited a slightly lower maximum specific growth rate (μmax = 0.12 ± 0.01 h-1) than strain TMB3400, with no ethanol production observed by the latter strain. Strain D5A+H also exhibited a shorter lag phase (4 h vs. 30 h) and complete removal of HMF, furfural and acetic acid from the fermentation broth within 24 h, reaching an ethanol concentration of 1.54 g/L at a yield (Yp/s) of 0.06 g/g xylose and a specific productivity of 2.08 g/gh. Evolutionary engineering profoundly affected the yeast metabolism, given that parental strain D5A+ exhibited an oxidative metabolism on xylose prior to strain development.ConclusionsPhysiological adaptations confirm improvements in the resistance to and conversion of inhibitors from pretreatment liquor with simultaneous enhancement of xylose to ethanol fermentation. These data support the sequential application of random mutagenesis followed by continuous culture under simultaneous selective pressure from inhibitors and xylose as primary carbon source.

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Furfural, 5‐hydroxymethyl furfural, and acetoin act as external electron acceptors during anaerobic fermentation of xylose in recombinant Saccharomyces cerevisiae

Cited by 168 publications

References 42 publications

Analysis of biodegradation performance of furfural and 5-hydroxymethylfurfural by Amorphotheca resinae ZN1

Analysis of biodegradation performance of furfural and 5-hydroxymethylfurfural by Amorphotheca resinae ZN1

Screening of Oleaginous Yeast Strains Tolerant to Lignocellulose Degradation Compounds

Simultaneously improving xylose fermentation and tolerance to lignocellulosic inhibitors through evolutionary engineering of recombinant Saccharomyces cerevisiaeharbouring xylose isomerase

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