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dc.creatorLee, Sun-Mien
dc.creatorJellison, Tayloren
dc.creatorAlper, Hal S.en
dc.date.accessioned2015-09-09T15:50:18Zen
dc.date.available2015-09-09T15:50:18Zen
dc.date.issued2012-08en
dc.identifier.citationLee, Sun-Mi, Jellison, Taylor, Alper, Hal S., >Directed Evolution of Xylose Isomerase for Improved Xylose Catabolism and Fermentation in the Yeast Saccharomyces cerevisiae,> Appl. Environ. Microbiol. August 2012 vol. 78 no. 16 5708-5716. doi: 10.1128/AEM.01419-12.en
dc.identifier.issn0099-2240en
dc.identifier.urihttp://hdl.handle.net/2152/31070en
dc.description.abstractThe heterologous expression of a highly functional xylose isomerase pathway in Saccharomyces cerevisiae would have significant advantages for ethanol yield, since the pathway bypasses cofactor requirements found in the traditionally used oxidoreductase pathways. However, nearly all reported xylose isomerase-based pathways in S. cerevisiae suffer from poor ethanol productivity, low xylose consumption rates, and poor cell growth compared with an oxidoreductase pathway and, additionally, often require adaptive strain evolution. Here, we report on the directed evolution of the Piromyces sp. xylose isomerase (encoded by xylA) for use in yeast. After three rounds of mutagenesis and growth-based screening, we isolated a variant containing six mutations (E15D, E114G, E129D, T142S, A177T, and V433I) that exhibited a 77% increase in enzymatic activity. When expressed in a minimally engineered yeast host containing a gre3 knockout and tall and XKS1 overexpression, the strain expressing this mutant enzyme improved its aerobic growth rate by 61-fold and both ethanol production and xylose consumption rates by nearly 8-fold. Moreover, the mutant enzyme enabled ethanol production by these yeasts under oxygen-limited fermentation conditions, unlike the wild-type enzyme. Under microaerobic conditions, the ethanol production rates of the strain expressing the mutant xylose isomerase were considerably higher than previously reported values for yeast harboring a xylose isomerase pathway and were also comparable to those of the strains harboring an oxidoreductase pathway. Consequently, this study shows the potential to evolve a xylose isomerase pathway for more efficient xylose utilization.en
dc.description.sponsorshipUniversity of Texas at Austin Research Grant Programen
dc.language.isoEnglishen
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en
dc.subjectethanol-productionen
dc.subjectglucose-isomeraseen
dc.subjectpichia-stipitisen
dc.subjectexpressionen
dc.subjectreductaseen
dc.subjectstrainen
dc.subjectgenesen
dc.subjectdehydrogenaseen
dc.subjectmutagenesisen
dc.subjectpathwaysen
dc.subjectbiotechnology & applied microbiologyen
dc.subjectmicrobiologyen
dc.titleDirected Evolution Of Xylose Isomerase For Improved Xylose Catabolism And Fermentation In The Yeast Saccharomyces Cerevisiaeen
dc.typeArticleen
dc.rights.holderen
dc.description.departmentCivil, Architectural, and Environmental Engineeringen
dc.description.departmentChemical Engineeringen
dc.identifier.doi10.1128/aem.01419-12en
dc.identifier.urlen
dc.contributor.utaustinauthorLee, Sun-Mien
dc.contributor.utaustinauthorJellison, Tayloren
dc.contributor.utaustinauthorAlper, Hal S.en
dc.relation.ispartofserialApplied and Environmental Microbiologyen


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