yeasts with fil phenotype, stress resistant under growth and/or nutritional conditions

摘要

New stress resistant eukaryotic strains (preferably yeast strains, especially Saccharomyces cerevisiae strains) in the presence of fermentable sugar are prepared by: (1) conventional mutagenic treatment of the cells of the initial strain; (2) cultivating the cells to obtain a stationary phase; (3) incubating the cells in the stationary phase in the presence of at least one fermentable sugar to obtain the cells in their active metabolic state; (4) subjecting the cells, in their active metabolic state, to obtain a death rate of at least 99 %; (5) isolating the surviving cells; and (6) selecting the surviving cells with a specific phenotype. New stress resistant eukaryotic strains (preferably yeast strains, especially Saccharomyces cerevisiae strains) in the presence of fermentable sugar (e.g. glucose) are prepared by: (1) conventional mutagenic treatment of the cells of the initial strain; (2) cultivating the cells from the previous treatment to obtain a stationary phase; (3) incubating the cells in the stationary phase in the presence of at least one fermentable sugar (e.g. glucose, maltose, saccharose) to obtain the cells in their active metabolic state (e.g. fermentation and/or growth); (4) subjecting the cells to stress, in their active metabolic state, to obtain a death rate of at least 99 % (compared to the inoculum); (5) isolating the surviving cells; and (6) selecting the surviving cells with a characteristic phenotype comprising: (a) a growth (evaluated by a production or production yield of biomass on sugar during a period of time or by a growth rate under identical culture conditions) of at least 80 (especially 90) % of the inoculum; (b) a carbon dioxide release or metabolite production of at least 80 (especially 90) % of the inoculum; (c) a stress resistant property corresponding to a survival rate of at least 2 (especially 10) times higher than the survival rate of the inoculum under same growth conditions followed by thermal shock at 52 degrees C for 20 minutes, or at least 1.5 (especially 5) times higher than the survival rate of the inoculum under the same growth conditions followed by freezing at -20 degrees C for 24 hours. Independent claims are also included for: (1) a new industrial eukaryotic strain (preferably yeast strains, especially Saccharomyces cerevisiae strains) comprising a phenotype (as above); (2) a mutated gene comprising the specific phenotype; and (3) a eukaryotic strain transformed to obtain alleles of the mutated gene or analogs of these genes with a mutation conferring the specific phenotype.