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

dc.contributor.authorSmith, Justin
dc.contributor.authorVan Rensburg, Eugene
dc.contributor.authorGorgens, Johann F.
dc.date.accessioned2014-05-29T09:10:06Z
dc.date.available2014-05-29T09:10:06Z
dc.date.issued2014-05
dc.descriptionPublication of this article was funded by the Stellenbosch University Open Access Fund.en_ZA
dc.descriptionThe original publication is available at http://www.biomedcentral.com/1472-6750/14/41en_ZA
dc.descriptionPlease site as follows:en_ZA
dc.descriptionSmith, J., Van Rensburg, E., & Gorgens, J. F. 2014. Simultaneously improving xylose fermentation and tolerance to lignocellulosic inhibitors through evolutionary engineering of recombinant Saccharomyces cerevisiae harbouring xylose isomerase. BMC Biotechnology, 14:41, doi:10.1186/1472-6750-14-41.en_ZA
dc.description.abstractBackground: Yeasts 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. Results: Following 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. Conclusions: Physiological 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.en_ZA
dc.description.sponsorshipStellenbosch Universityen_ZA
dc.description.versionPublishers' Versionen_ZA
dc.identifier.citationSmith, J., Van Rensburg, E., & Gorgens, J. F. 2014. Simultaneously improving xylose fermentation and tolerance to lignocellulosic inhibitors through evolutionary engineering of recombinant Saccharomyces cerevisiae harbouring xylose isomerase. BMC Biotechnology, 14:41, doi:10.1186/1472-6750-14-41.en_ZA
dc.identifier.issn1472-6750 (Online)
dc.identifier.otherdoi:10.1186/1472-6750-14-41
dc.identifier.urihttp://hdl.handle.net/10019.1/86852
dc.language.isoen_ZAen_ZA
dc.publisherBioMed Centralen_ZA
dc.rights.holderAuthors retain copyrighten_ZA
dc.subjectSaccharomyces cerevisiaeen_ZA
dc.subjectYeast hardeningen_ZA
dc.subjectEvolutionary engineeringen_ZA
dc.titleSimultaneously improving xylose fermentation and tolerance to lignocellulosic inhibitors through evolutionary engineering of recombinant Saccharomyces cerevisiae harbouring xylose isomeraseen_ZA
dc.typeArticleen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
smith_simultaneously_2014.pdf
Size:
843.33 KB
Format:
Adobe Portable Document Format
Description:
Publisher's Version
License bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
1.95 KB
Format:
Item-specific license agreed upon to submission
Description: