Abstract: The present invention relates to a method of preparing a strain of sugar fermenting Saccharomyces cerevisiae with capability to ferment xylose, wherein said method comprises different procedural steps. The method comprises mating a first sporulated Saccharomyces cerevisiae strain with a second Saccharomyces cerevisiae haploid strain. Thereafter, screening for mated cells is performed, growing such mated cells, and verifying that mated cells exhibit basic morphology by microscopic inspection. Thereafter, creation of a mixture of the mated cells is performed, subjecting the mixture to continuous chemostat lignocellulose cultivation and obtaining the sugar fermenting Saccharomyces cerevisiae cells with capability to ferment xylose is performed. The invention also comprises strains obtained by said method.

Abstract: The present invention relates to a method of preparing a strain of sugar fermenting Saccharomyces cerevisiae with capability to ferment xylose, wherein said method comprises different procedural steps. The method comprises mating a first sporulated Saccharomyces cerevisiae strain with a second Saccharomyces cerevisiae haploid strain. Thereafter, screening for mated cells is performed, growing such mated cells, and verifying that mated cells exhibit basic morphology by microscopic inspection. Thereafter, creation of a mixture of the mated cells is performed, subjecting the mixture to continuous chemostat lignocellulose cultivation and obtaining the sugar fermenting Saccharomyces cerevisiae cells with capability to ferment xylose is performed. The invention also comprises strains obtained by said method.

Abstract: The present invention relates to a method of preparing a strain of sugar fermenting Saccharomyces cerevisiae with capability to ferment xylose, wherein said method comprises different procedural steps. The method comprises mating a first sporulated Saccharomyces cerevisiae strain with a second Saccharomyces cerevisiae haploid strain. Thereafter, screening for mated cells is performed, growing such mated cells, and verifying that mated cells exhibit basic morphology by microscopic inspection. Thereafter, creation of a mixture of the mated cells is performed, subjecting the mixture to continuous chemostat cultivation and obtaining the sugar fermenting Saccharomyces cerevisiae cells with capability to ferment xylose is performed. The invention also comprises strains obtained by said method.

Abstract: The present invention relates to a method of preparing a strain of sugar fermenting Saccharomyces cerevisiae with capability to ferment xylose, wherein said method comprises different procedural steps. The method comprises mating a first sporulated Saccharomyces cerevisiae strain with a second Saccharomyces cerevisiae haploid strain. Thereafter, screening for mated cells is performed, growing such mated cells, and verifying that mated cells exhibit basic morphology by microscopic inspection. Thereafter, creation of a mixture of the mated cells is performed, subjecting the mixture to continuous chemostat cultivation and obtaining the sugar fermenting Saccharomyces cerevisiae cells with capability to ferment xylose is performed. The invention also comprises strains obtained by said method.

Abstract: A method for producing a strain of Saccharomyces cerevisiae with introduced genes coding for xylose reductase, xylitol dehydrogenase and xylulokinase and with improved ethanol production, improved xylose conversion and reduced xylitol production is described. The method comprises culturing the cells in a repetitive batch series in a medium at a xylose concentration of about 15-25 g/l and at a temperature of about 28-32° C., and thereafter lowering the xylose concentration in at least one step at a temperature of about 28-32° C. to obtain an increased selection pressure for improved xylose fermentation, improved ethanol production and reduced xylitol production, and continuing the culturing of the cells in said repetitive batch series. Further, strains of Saccharomyces cerevisiae obtained by the method according to the invention are described.

Abstract: A method for producing a strain of Saccharomyces cerevisiae with introduced genes coding for xylose reductase, xylitol dehydrogenase and xylulokinase and with improved ethanol production, improved xylose conversion, reduced xylitol production and improved inhibitor tolerance is described. The method comprises culturing a strain of Saccharomyces cerevisiae at a continuous mode with a medium comprising essentially only xylose as carbon source at a temperature of 25-38° C., preferably 30-35° C., and an airflow of 0.040-0.055 vvm, and increasing the dilution rate to maintain a constant cell level, said cell level being in the range of 1.5-3.0 determined by optical density or equivalent analytical means, and adding at least one inhibitor to the cells and gradually increasing the addition of said inhibitor. Further, strains of Saccharomyces cerevisiae obtained by the method according to the invention are described.

Abstract: The present invention relates to a method for producing a L-arabinose utilizing yeast strain for the production of ethanol, whereby a yeast strain is modified by introducing and expressing araA gene (L-arabinose isomerase), araB gene (L-ribulokinase D121-N) and araD gene (L-ribulose-5-P 4-epimerase) and carrying additional mutations in its genome or overexpressing a TAL1 (transaldolase) gene, enabling it to consume L-arabinose, to use it as the only carbon source, and to produce ethanol, as well as a method for producing ethanol using such a modified strain.

Abstract: A method for producing a strain of Saccharomyces cerevisiae with introduced genes coding for xylose reductase, xylitol dehydrogenase and xylulokinase and with improved ethanol production, improved xylose conversion and reduced xylitol production is described. The method comprises culturing the cells in a repetitive batch series in a medium at a xylose concentration of about 15-25 g/l and at a temperature of about 28-32° C., and thereafter lowering the xylose concentration in at least one step at a temperature of about 28-32° C. to obtain an increased selection pressure for improved xylose fermentation,improved ethanol production and reduced xylitol production, and continuing the culturing of the cells in said repetitive batch series. Further, strains of Saccharomyces cerevisiae obtained by the method according to the invention are described.

Abstract: A method for producing a strain of Saccharomyces cerevisiae with introduced genes coding for xylose reductase, xylitol dehydrogenase and xylulokinase and with improved ethanol production, improved xylose conversion, reduced xylitol production and improved inhibitor tolerance is described. The method comprises culturing a strain of Saccharomyces cerevisiae at a continuous mode with a medium comprising essentially only xylose as carbon source at a temperature of 25-38° C., preferably 30-35° C., and an airflow of 0.040-0.055 vvm, and increasing the dilution rate to maintain a constant cell level, said cell level being in the range of 1.5-3.0 determined by optical density or equivalent analytical means, and adding at least one inhibitor to the cells and gradually increasing the addition of said inhibitor. Further, strains of Saccharomyces cerevisiae obtained by the method according to the invention are described.

Abstract: The present invention relates to an ethanol producing microbial strain, such as Saccharomyces cerevisiae strain, being able to grow and produce ethanol from lignocellulosic hydrolysates comprising growth inhibiting compounds of the group furfural and 5-hydroxy-methyl furfural, in a batch, fed-batch or continuous fermentation, said microbial strain being tolerant to such inhibiting compounds, which strain is upregulated and/or over expressed with regard to one or more of the following genes: LAT1, ALD6, ADH5, ADH6, GDH3, OYE3, SER3, GND2, MDH2, IDP3, ADH7, AAD15, ERG27, HMG1, LYS5, SPS19, SGE1.

Abstract: The present invention relates to an ethanol producing microbial strain, such as Saccharomyces cerevisiae strain, being able to grow and produce ethanol from lignocellulosic hydrolysates comprising growth inhibiting compounds of the group furfural and 5-hydroxy-methyl furfural, in a batch, fed-batch or continuous fermentation, said microbial strain being tolerant to such inhibiting compounds, which strain is upregulated and/or over expressed with regard to one or more of the following genes: LAT1, ALD6, ADH5, ADH6, GDH3, OYE3, SER3, GND2, MDH2, IDP3, ADH7, AAD15, ERG27, HMG1, LYS5, SPS19, SGE1.

Abstract: A S. cerevisiae strain expressing both arabinose and xylose utilization pathways, and in particular to a S. cerevisiae strain fermenting both arabinose and xylose to ethanol, and more particularly a S. cerevisiae strain with overexpression or upregulation of xylose- or aldose reductase (XR, AR) with xylitol dehydrogenase (XDH) together with overexpression or upregulation of genes forming an arabinose utilization pathway. The invention encompasses both laboratory and industrial strain having these properties.

Abstract: The present invention relates to a method for producing a L-arabinose utilizing yeast strain for the production of ethanol, whereby a yeast strain is modified by introducing and expressing araA gene (L-arabinose isomerase), araB gene (L-ribulokinase D121-N) and araD gene (L-ribulose-5-P 4-epimerase) and carrying additional mutations in its genome or overexpressing a TAL1 (transaldolase) gene, enabling it to consume L-arabinose, to use it as the only carbon source, and to produce ethanol, as well as a method for producing ethanol using such a modified strain.

Abstract: The present invention relates to a method for obtaining a recombinant yeast of Saccharomyces cerevisiae, which ferments lignocellulose raw materials to ethanol, including introducing DNA into a yeast so as to cause the yeast to have introduced genes encoding xylose reductase, xylitol dehydrogenase and xylulokinase.