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Automated UV-C Mutagenesis of Kluyveromyces marxianus NRRL Y-1109 and Selection for Microaerophilic Growth and Ethanol Production at Elevated Temperature on Biomass Sugars
- Hughes, Stephen R., Bang, Sookie S., Cox, Elby J., Schoepke, Andrew, Ochwat, Kate, Pinkelman, Rebecca, Nelson, Danielle, Qureshi, Nasib, Gibbons, William R., Kurtzman, Cletus P., Bischoff, Kenneth M., Liu, Siqing, Cote, Gregory L., Rich, Joseph O., Jones, Marjorie A., Cedeño, David, Doran-Peterson, Joy, Riaño-Herrera, Nestor M., Rodríguez-Valencia, Nelson, López-Nuñez, Juan C.
- Journal of laboratory automation 2013 v.18 no.4 pp. 276
- 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.