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Synergetic effect of yeast cell-surface expression of cellulase and expansin-like protein on direct ethanol production from cellulose.

Nakatani Y, Yamada R, Ogino C, Kondo A - Microb. Cell Fact. (2013)

Bottom Line: Here, to improve the direct conversion of cellulose to ethanol, yeast Saccharomyces cerevisiae co-displaying cellulase and expansin-like protein on the cell surface were constructed and examined for direct ethanol fermentation performance.This result clearly demonstrated that yeast cell-surface expressed cellulase and expansin-like protein act synergistically to breakdown cellulose.To our knowledge, this is the first report to demonstrate the synergetic effect of co-expressing cellulase and expansin-like protein on a yeast cell surface, which may be a promising strategy for constructing direct ethanol fermenting yeast from cellulose.

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ABSTRACT

Background: Numerous studies have examined the direct fermentation of cellulosic materials by cellulase-expressing yeast; however, ethanol productivity in these systems has not yet reached an industrial level. Certain microorganisms, such as the cellulolytic fungus Trichoderma reesei, produce expansin-like proteins, which have a cellulose-loosening effect that may increase the breakdown of cellulose. Here, to improve the direct conversion of cellulose to ethanol, yeast Saccharomyces cerevisiae co-displaying cellulase and expansin-like protein on the cell surface were constructed and examined for direct ethanol fermentation performance.

Results: The cellulase and expansin-like protein co-expressing strain showed 246 mU/g-wet cell of phosphoric acid swollen cellulose (PASC) degradation activity, which corresponded to 2.9-fold higher activity than that of a cellulase-expressing strain. This result clearly demonstrated that yeast cell-surface expressed cellulase and expansin-like protein act synergistically to breakdown cellulose. In fermentation experiments examining direct ethanol production from PASC, the cellulase and expansin-like protein co-expressing strain produced 3.4 g/L ethanol after 96 h of fermentation, a concentration that was 1.4-fold higher than that achieved by the cellulase-expressing strain (2.5 g/L).

Conclusions: The PASC degradation and fermentation ability of an engineered yeast strain was markedly improved by co-expressing cellulase and expansin-like protein on the cell surface. To our knowledge, this is the first report to demonstrate the synergetic effect of co-expressing cellulase and expansin-like protein on a yeast cell surface, which may be a promising strategy for constructing direct ethanol fermenting yeast from cellulose.

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PASCase activity of cellulase and expansin-like protein co-expressing strain. Data are averages from three independent experiments (error bars represent SE).
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Figure 2: PASCase activity of cellulase and expansin-like protein co-expressing strain. Data are averages from three independent experiments (error bars represent SE).

Mentions: To confirm the synergistic effect of cell-surface expressed cellulase and expansin-like protein on the degradation of PASC, the PASCase activity of a cellulase and expansin-like protein co-expressing strain was examined (Figure 2). The PASCase activities of strains co-expressing AoelpI and cellulase, and SWOI and cellulase were 246 and 229 mU/g-wet cell, respectively, which corresponded to 2.9- and 2.3-fold higher PASCase activity, respectively, than the cellulase-expressing strain MT8-1/cocδBEC1.


Synergetic effect of yeast cell-surface expression of cellulase and expansin-like protein on direct ethanol production from cellulose.

Nakatani Y, Yamada R, Ogino C, Kondo A - Microb. Cell Fact. (2013)

PASCase activity of cellulase and expansin-like protein co-expressing strain. Data are averages from three independent experiments (error bars represent SE).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3716962&req=5

Figure 2: PASCase activity of cellulase and expansin-like protein co-expressing strain. Data are averages from three independent experiments (error bars represent SE).
Mentions: To confirm the synergistic effect of cell-surface expressed cellulase and expansin-like protein on the degradation of PASC, the PASCase activity of a cellulase and expansin-like protein co-expressing strain was examined (Figure 2). The PASCase activities of strains co-expressing AoelpI and cellulase, and SWOI and cellulase were 246 and 229 mU/g-wet cell, respectively, which corresponded to 2.9- and 2.3-fold higher PASCase activity, respectively, than the cellulase-expressing strain MT8-1/cocδBEC1.

Bottom Line: Here, to improve the direct conversion of cellulose to ethanol, yeast Saccharomyces cerevisiae co-displaying cellulase and expansin-like protein on the cell surface were constructed and examined for direct ethanol fermentation performance.This result clearly demonstrated that yeast cell-surface expressed cellulase and expansin-like protein act synergistically to breakdown cellulose.To our knowledge, this is the first report to demonstrate the synergetic effect of co-expressing cellulase and expansin-like protein on a yeast cell surface, which may be a promising strategy for constructing direct ethanol fermenting yeast from cellulose.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Numerous studies have examined the direct fermentation of cellulosic materials by cellulase-expressing yeast; however, ethanol productivity in these systems has not yet reached an industrial level. Certain microorganisms, such as the cellulolytic fungus Trichoderma reesei, produce expansin-like proteins, which have a cellulose-loosening effect that may increase the breakdown of cellulose. Here, to improve the direct conversion of cellulose to ethanol, yeast Saccharomyces cerevisiae co-displaying cellulase and expansin-like protein on the cell surface were constructed and examined for direct ethanol fermentation performance.

Results: The cellulase and expansin-like protein co-expressing strain showed 246 mU/g-wet cell of phosphoric acid swollen cellulose (PASC) degradation activity, which corresponded to 2.9-fold higher activity than that of a cellulase-expressing strain. This result clearly demonstrated that yeast cell-surface expressed cellulase and expansin-like protein act synergistically to breakdown cellulose. In fermentation experiments examining direct ethanol production from PASC, the cellulase and expansin-like protein co-expressing strain produced 3.4 g/L ethanol after 96 h of fermentation, a concentration that was 1.4-fold higher than that achieved by the cellulase-expressing strain (2.5 g/L).

Conclusions: The PASC degradation and fermentation ability of an engineered yeast strain was markedly improved by co-expressing cellulase and expansin-like protein on the cell surface. To our knowledge, this is the first report to demonstrate the synergetic effect of co-expressing cellulase and expansin-like protein on a yeast cell surface, which may be a promising strategy for constructing direct ethanol fermenting yeast from cellulose.

Show MeSH
Related in: MedlinePlus