Journal of Pure and Applied MicrobiologyVol. 8 No. 2

A Thermostable Candida molischiana Mutant Capable of Ethanol Production at Elevated Temperatures

Melanie R. Geiger, William R. Gibbons and Thomas P. West*

Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.

Received on 21 June 2013 and accepted on 14 August 2013

 

ABSTRACT

The isolation of a mutant strain of Candida molischiana ATCC 2516 with increased thermotolerance compared to its parent strain was accomplished using nitrous acid mutagenesis and resistance to the glucose analogue 2-deoxy-D-glucose. Mutagenized ATCC 2516 cells were spread on a minimal medium containing raffinose and 2-deoxy-D-glucose with the resistant colonies being subsequently screened for thermotolerance at 45oC. A thermotolerant mutant strain was identified and its ability to utilize glucose at selected temperatures was compared to its parent strain. The mutant strain was capable of increased ethanol production using 20 g l-1 glucose as a carbon source at 35oC compared to the wild strain. The mutant strain also produced ethanol from glucose at 45oC while the parent strain did not. The isolation procedure involving 2-deoxy-D-glucose described in this study could provide a rapid method for the isolation of thermotolerant mutants from other yeast species with an increased ability to produce ethanol at higher temperatures.

Keywords : Thermostable, Mutant, Glucose, Utilization, Ethanol fermentation, Candida.