Isolation and evaluation of xylose-fermenting thermotolerant yeasts for bioethanol production

Nweze, Julius Eyiuche; Ndubuisi, Ifeanyi A.; Murata, Yoshinori; Omae, Hide; Ogbonna, James C.

doi:10.1080/17597269.2018.1564480

Cited by 21 publications

(16 citation statements)

References 47 publications

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“…The best reported industrial S. cerevisiae yeast strain was able to consume both glucose and xylose with an ethanol yield of 0.46 at 32 °C, however, the fermentation rate was significantly reduced at 39 °C [19,20]. The thermotolerant isolates of Pichia kudriavzevii and Candida tropicalis fermented a mixture of glucose and xylose (6:4) with ethanol yield 0.33 and 0.36 g ethanol/g sugar, respectively, at 42 °C [21]. Spathaspora passalidarum that is capable of co-fermenting xylose and cellobiose in the presence of glucose under oxygen-limiting conditions was able to produce 0.33 g/L ethanol/g sugar at 40 °C during mixed sugar fermentation [22].…”

Section: Discussionmentioning

confidence: 99%

Engineering of sugar transporters for improvement of xylose utilization during high-temperature alcoholic fermentation in Ogataea polymorpha yeast

et al. 2020

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Background: Xylose transport is one of the bottlenecks in the conversion of lignocellulosic biomass to ethanol. Xylose consumption by the wild-type strains of xylose-utilizing yeasts occurs once glucose is depleted resulting in a long fermentation process and overall slow and incomplete conversion of sugars liberated from lignocellulosic hydrolysates. Therefore, the engineering of endogenous transporters for the facilitation of glucose-xylose co-consumption is an important prerequisite for efficient ethanol production from lignocellulosic hydrolysates. Results: In this study, several engineering approaches formerly used for the low-affinity glucose transporters in Saccharomyces cerevisiae, were successfully applied for earlier identified transporter Hxt1 in Ogataea polymorpha to improve xylose consumption (engineering involved asparagine substitution to alanine at position 358 and replacement of N-terminal lysine residues predicted to be the target of ubiquitination for arginine residues). Moreover, the modified versions of S. cerevisiae Hxt7 and Gal2 transporters also led to improved xylose fermentation when expressed in O. polymorpha. Conclusions: The O. polymorpha strains with modified Hxt1 were characterized by simultaneous utilization of both glucose and xylose, in contrast to the wild-type and parental strain with elevated ethanol production from xylose. When the engineered Hxt1 transporter was introduced into constructed earlier advanced ethanol producer form xylose, the resulting strain showed further increase in ethanol accumulation during xylose fermentation. The overexpression of heterologous S. cerevisiae Gal2 had a less profound positive effects on sugars uptake rate, while overexpression of Hxt7 revealed the least impact on sugars consumption.

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Section: Discussionmentioning

confidence: 99%

Engineering of sugar transporters for improvement of xylose utilization during high-temperature alcoholic fermentation in Ogataea polymorpha yeast

et al. 2020

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“…is yeast was investigated by several authors for its ability to produce ethanol from D-xylose [24][25][26][27].…”

Section: Discussionmentioning

confidence: 99%

“…Molelekoa et al [ 23 ] isolated non- Saccharomyces yeast from marula fruit and found Pichia kudriavzevii, a yeast known for its pentose-fermenting ability. This yeast was investigated by several authors for its ability to produce ethanol from D-xylose [ 24 – 27 ].…”

Section: Discussionmentioning

confidence: 99%

“…The application of thermotolerant pentose-fermenting yeasts for bioethanol production possesses advantages over low-temperature ethanol fermentation. These include a higher hydrolysis rate for enzymes, ethanol yield, lower contamination risk, and lower cooling costs [ 27 ]. In this study, five strains of M. caribbica (D14W2, D14YE6, D28L3, D28L3, and Mu 2.2f) grew at 40°C on agar plates using L-arabinose as carbon source, and these strains were included in the adaptation process ( Table 4 ).…”

Section: Discussionmentioning

confidence: 99%

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The Improvement of Bioethanol Production by Pentose-Fermenting Yeasts Isolated from Herbal Preparations, the Gut of Dung Beetles, and Marula Wine

Moremi

Rensburg

Grange

2020

International Journal of Microbiology

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Efficient conversion of pentose sugars to ethanol is important for an economically viable lignocellulosic bioethanol process. Ten yeasts fermenting both D-xylose and L-arabinose were subjected to an adaptation process with L-arabinose as carbon source in a medium containing acetic acid. Four Meyerozyma caribbica-adapted strains were able to ferment L-arabinose to ethanol in the presence of 3 g/L acetic acid at 35°C. Meyerozyma caribbica Mu 2.2f fermented L-arabinose to produce 3.0 g/L ethanol compared to the parental strain with 1.0 g/L ethanol in the absence of acetic acid. The adapted M. caribbica Mu 2.2f strain produced 3.6 and 0.8 g/L ethanol on L-arabinose and D-xylose, respectively, in the presence of acetic acid while the parental strain failed to grow. In a bioreactor, the adapted M. caribbica Mu 2.2f strain produced 5.7 g/L ethanol in the presence of 3 g/L acetic acid with an ethanol yield and productivity of 0.338 g/g and 0.158 g/L/h, respectively, at a KLa value of 3.3 h−1. The adapted strain produced 26.7 g/L L-arabitol with a yield of 0.900 g/g at a KLa value of 4.9 h−1.

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“…In recent years, increasing interest has been shown in lignocellulose biomass as renewable and sustainable energy resources. Bioethanol, a biofuel from lignocellulosic biomass, is gaining increasing attention as an alternative fuel due to fluctuations in oil prices, reduced oil reserves, and important environmental issues associated with greenhouse gas emissions [8][9][10][11][12][13]. Lignocellulose is composed of three major carbohydrate polymers: cellulose, hemicelluloses and lignin [1,8,9].…”

Section: Introductionmentioning

confidence: 99%

Adaptive Laboratory Evolution for Multistress Tolerance, including Fermentability at High Glucose Concentrations in Thermotolerant Candida tropicalis

et al. 2022

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Candida tropicalis, a xylose-fermenting yeast, has the potential for converting cellulosic biomass to ethanol. Thermotolerant C. tropicalis X-17, which was isolated in Laos, was subjected to repetitive long-term cultivation with a gradual increase in temperature (RLCGT) in the presence of a high concentration of glucose, which exposed cells to various stresses in addition to the high concentration of glucose and high temperatures. The resultant adapted strain demonstrated increased tolerance to ethanol, furfural and hydroxymethylfurfural at high temperatures and displayed improvement in fermentation ability at high glucose concentrations and xylose-fermenting ability. Transcriptome analysis revealed the up-regulation of a gene for a glucose transporter of the major facilitator superfamily and genes for stress response and cell wall proteins. Additionally, hydropathy analysis revealed that three genes for putative membrane proteins with multiple membrane-spanning segments were also up-regulated. From these findings, it can be inferred that the up-regulation of genes, including the gene for a glucose transporter, is responsible for the phenotype of the adaptive strain. This study revealed part of the mechanisms of fermentability at high glucose concentrations in C. tropicalis and the results of this study suggest that RLCGT is an effective procedure for improving multistress tolerance.

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Isolation and evaluation of xylose-fermenting thermotolerant yeasts for bioethanol production

Cited by 21 publications

References 47 publications

Engineering of sugar transporters for improvement of xylose utilization during high-temperature alcoholic fermentation in Ogataea polymorpha yeast

Engineering of sugar transporters for improvement of xylose utilization during high-temperature alcoholic fermentation in Ogataea polymorpha yeast

The Improvement of Bioethanol Production by Pentose-Fermenting Yeasts Isolated from Herbal Preparations, the Gut of Dung Beetles, and Marula Wine

Adaptive Laboratory Evolution for Multistress Tolerance, including Fermentability at High Glucose Concentrations in Thermotolerant Candida tropicalis

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