Abstract

Saccharomyces cerevisiae, ATCC 76740 was mutated after treatment with diethyl sulfate (DES) in the paper. Successive mutants showed high tolerance against both higher concentrations of ethanol and furfural and higher temperature. In addition, the mutant 4D-6 showed 2.2 fold in ethanol yield to the wild type at 37°C in shake culture. Furthermore, in order to improve the ethanol production of 4D-6, the sequential statistical approach was applied to optimize compositions of the medium, which the optimal medium was comprised 29 g/L glucose, 10 g/L yeast extract, 20 g/L peptone, 1.5 g/L KH₂PO₄, 1.81 g/L KNO₃ and 0.078 g/L ZnCl₂. In a word, the maximum ethanol production of fermentation 4D-6 in optimal medium was 11.2 g/L, which was about 1.6-fold to the original medium and 3.6-fold to the wild type stain in the original medium. The relative error between expected value and validation experimental value was 2.3%.

Key words: High tolerance, high yield of ethanol, mutation breeding, Plackett-Burman experimental design, artificial neural network, genetic algorithm.