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.

Provided herein are recombinant microorganisms having two or more copies of a nucleic acid sequence encoding xylose isomerase, wherein the nucleic acid encoding the xylose isomerase is an exogenous nucleic acid. Optionally, the recombinant microorganisms include at least one nucleic acid sequence encoding a xylulose kinase and/or at least one nucleic acid sequence encoding a xylose transporter. The provided recombinant microorganisms are capable of growing on xylose as a carbon source.

One aspect of the invention relates to industrial bioconversion of the xylose portion of biomass materials into fuels and chemicals. Another aspect of the invention relates to industrial bioconversion of the xylan portion of biomass materials into fuels and chemicals. In one embodiment, the invention is directed to the bacterium Clostridium thermocellum, a highly cellulolytic organism that has much potential as a biocatalyst in a consolidated bioprocess configuration. In some embodiments, the invention is a genetic modification that confers the ability to ferment xylose to C. thermocellum and the strains created with this modification. In some embodiments, the genetic modification is composed of two genes contained in an operon from T. saccharolyticum. The genes express proteins with xylose isomerase (XI) and xylulokinase activites (XK). In other embodiments, the invention relates to a recombinant Clostridium thermocellum host cell capable of fermenting xylan.

Provided are microorganisms, e.g., the Saccharomyces yeast, that have been made able to co-ferment xylose sugar-obtained from hydrolyzing plant cellulosic biomass form trees, grasses, straws, etc., with glucose that can be obtained from hydrolyzing either edible feedstocks such as starch, cane sugar, etc. or from hydrolyzing cellulose from various types of non-edible cellulosic biomass. The microorganisms are also capable of expressing an amylase, e.g., glucoamylase, having nonnegligible enzymatic activity, capable of producing glucose from oligo- or polysaccharides obtained by treating soluble starch with -amylase. In some embodiments, nucleotidic material is provided comprising genes actively expressing xylose reductase, xylitol dehydrogenase and xylulokinase as well as an active gene expressing glucoamylase. Vectors and other compositions of matter are provided as.

Recombinant yeasts comprising recombinant xylose reductase, xylitol dehydrogenase, and/or xylulokinase genes and methods of using same, such as for producing ethanol from xylose-containing feedstocks.

An engineered yeast strain capable of efficient fermentation of xylose to ethanol, and methods of making and using the strain, are provided.

Provided herein are methods of making microorganisms modified for increased xylose consumption as compared to unmodified microorganisms. The methods include providing xylose-consuming microorganisms comprising two or more copies of a nucleic acid sequence encoding xylose isomerase and two or more copies of a nucleic acid sequence encoding a xylose kinase, culturing the microorganisms in medium containing xylose and harvesting a portion of the microorganisms. These steps are repeated multiple times. The microorganisms are then isolated. The isolated microorganisms have increased xylose consumption rates compared to control xylose-consuming microorganisms. Also provided are a population of microorganisms made by the provided methods. Methods of culturing the population of microorganisms and methods of reducing xylitol production in cultures comprising the population of microorganisms are provided.

Provided herein are compositions and methods for the fermentative production of 2,3-butanediol (2,3-BDO), compositions and methods for making methyl ethyl ketone (MEK), and methods of inducing drought tolerance in plants.

The present invention relates to the preparation of ortho-aminobenzoic acid by means of microbial fermentation, wherein mixtures of glucose and xylose are used as fermentable substrates.