U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Main content area

Automated UV-C Mutagenesis of Kluyveromyces marxianus NRRL Y-1109 and Selection for Microaerophilic Growth and Ethanol Production at Elevated Temperature on Biomass Sugars

Stephen R. Hughes, Sookie S. Bang, Elby J. Cox, Andrew Schoepke, Kate Ochwat, Rebecca Pinkelman, Danielle Nelson, Nasib Qureshi, William R. Gibbons, Cletus P. Kurtzman, Kenneth M. Bischoff, Siqing Liu, Gregory L. Cote, Joseph O. Rich, Marjorie A. Jones, David Cedeño, Joy Doran-Peterson, Nestor M. Riaño-Herrera, Nelson Rodríguez-Valencia, Juan C. López-Nuñez
Journal of laboratory automation 2013 v.18 no.4 pp. 276-290
Kluyveromyces marxianus, Saccharomyces cerevisiae, anaerobic conditions, biomass, carbon, ethanol, ethanol fuels, ethanol production, galactose, galacturonic acid, glucose, mutagenesis, mutants, pectins, robots, starch, sucrose, temperature, ultraviolet radiation, xylose, yeasts
The yeast Kluyveromyces marxianus is a potential microbial catalyst for fuel ethanol production from a wide range of biomass substrates. To improve its growth and ethanol yield at elevated temperature under microaerophilic conditions, K. marxianus NRRL Y-1109 was irradiated with UV-C using automated protocols on a robotic platform for picking and spreading irradiated cultures and for processing the resulting plates. The plates were incubated under anaerobic conditions on xylose or glucose for 5 mo at 46 °C. Two K. marxianus mutant strains (designated 7-1 and 8-1) survived and were isolated from the glucose plates. Both mutant strains, but not wild type, grew aerobically on glucose at 47 °C. All strains grew anaerobically at 46 °C on glucose, galactose, galacturonic acid, and pectin; however, only 7-1 grew anaerobically on xylose at 46 °C. Saccharomyces cerevisiae NRRL Y-2403 did not grow at 46 °C on any of these substrates. With glucose as a carbon source, ethanol yield after 3 d at 46 °C was higher for 8-1 than for wild type (0.51 and 0.43 g ethanol/g glucose, respectively). With galacturonic acid as a carbon source, the ethanol yield after 7 d at 46 °C was higher for 7-1 than for wild type (0.48 and 0.34 g ethanol/g galacturonic acid, respectively). These mutant strains have potential application in fuel ethanol production at elevated temperature from sugar constituents of starch, sucrose, pectin, and cellulosic biomass.