73 results about "Xylitol dehydrogenase" patented technology

Described are recombinant yeast which ferment xylose to ethanol and which maintain their ability to do so when cultured for numerous generations in non-selective media. The preferred yeast contain multiple copies of integrated genes encoding xylose reductase, xylitol dehydrogenase, and xylulokinase fused to promoters which are non-glucose inhibited and which do not require xylose for induction. Also described are preferred methods for integrating multiple copies of exogenous DNA into host cells by transforming cells with replicative/integrative vectors, and then replicating the cells a number of times under selective pressure to promote retention of the vector in subsequent generations. The replicated vectors thus serve to integrate multiple copies of the exogenous DNA into the host cells throughout the replication/selection phase. Thereafter the selective pressure can be removed to promote loss of the vector in subsequent generations, leaving stable integrants of the exogenous DNA.

The present invention relates to a method for preparing an ethanol producing, xylose utilizing strain of Saccharomyces cerevisiae comprising genes for overexpression of xylose reductase, xylitol dehydrogenase and xylulokinase, wherein in addition to said genes for production o phosphoacetyltransferase, and acetaldehyde dehydrogenase are introduced and optionally overexpressed.

The present invention relates to DNA encoding novel xylitol dehydrogenase and a method for using the same. Specifically, the present invention comprises providing the nucleic acid sequence of a xylitol dehydrogenase gene from Candida shehatae and introducing this gene into a host organism, thereby producing a microorganism having the ability to utilize xylose.

Disclosed are xylose-fermenting recombinant yeast strains expressing xylose reductase, xylitol dehydrogenase, and xylulokinase and having reduced expression of PHO13 or a PHO13 ortholog, as well as methods of fermenting xylose to obtain ethanol using the recombinant yeast strains.

The present invention relates to the field of the methods for obtaining yeast strains producing ethanol, of the thereby produced strains, and of the industrial production of ethanol from said strains.

More particularly, the present invention describes in its most general aspect, a method for preparing yeasts from Saccharomyces cerevisiae strains by integration into the genome of the yeast of at least one gene coding for xylose isomerase and of at least one gene coding for xylitol dehydrogenase.

The strain of the invention is useful for producing ethanol from a medium comprising at least one pentose, preferably xylose or a xylose and arabinose mixture.

The invention discloses recombinant saccharomyces cerevisiae for producing dammarenediol and protopanoxadiol using xylose and a construction method. The construction method comprises the steps of replacing a promoter of a saccharomyces cerevisiae xylulokinase gene XKS1 with a promoter PFBA1 by virtue of a homologous recombination method, introducing xylose reductase XYL1 and a xylitol dehydrogenase XYL2 expression cassette, increasing the activities of transketolase TKL1 and transaldolase TAL1 so as to obtain recombinant bacteria 1, introducing a farnesyl-diphosphate farnesyltransferase gene ERG9, a squalene monooxygenase gene ERG1 and a dammarenediol synthase gene DS into the recombinant bacteria 1 so as to obtain recombinant bacteria 2, and introducing a nicotinamide adenine dinucleotide-hydroxymethylglutaryl coenzyme A reductase gene NADH-HMGr, farnesyl diphosphatesynthase ERG20 and a protopanoxadiol synthase-cytochrome P450 reductase fusion protein gene PPDS-ATR1 into the recombinant bacteria 2, so as to obtain recombinant bacteria 3. According to the recombinant saccharomyces cerevisiae, dammarenediol and protopanoxadiol can be artificially synthesized by virtue of xylose.

The invention discloses a method for producing D-1,2,4-butantriol through bio-converting cellulosic hydrolyzate. The method comprises the steps of constructing genes for cloning and expressing 2-keto acid decarboxylase, D-xylitol dehydrogenase, D-xylonic acid dehydrase and D-alcohol dehydrogenase, shifting the constructed genes into cells of host bacteria for knocking out xylose isomerase so as to obtain genetic engineering strains, culturing the genetic engineering strains, inoculating the genetic engineering strains to the cellulosic hydrolyzate, and carrying out fermentation so as to produce the D-1,2,4-butantriol. The method disclosed by the invention is easy and feasible, is high in yield and is applicable to industrialization.

The invention discloses a recombinant saccharomyces cerevisiae engineering strain and application thereof. GAP gene fragments are cloned from Pichiapastoris GS115, and induced promoters of a PYES2 carrier are replaced by constitutive GAP promoters. Then an xylose reductase gene xyl1 fragment and an xylitol dehydrogenase gene xyl2 fragment are connected together and introduced into a PYES2 carrier containing constitutive GAP promoters to constitute a PYES2- GAP-xyl1-xyl2 plasmid. The plasmid is introduced into saccharomyces cerevisiae. The engineering strain of the present invention can co-express xylose reductase and xylitol dehydrogenase, has a high activity and high expression level of xylose reductase and xylitol dehydrogenase. In addition, the invention can efficiently utilize pentose and hexose degraded from cellulose and hemicellulose in straws, so as to increase output of fuel ethanol, reduce production costs and reduce environmental pollution. Therefore, the engineering strain can be used for producing fuel ethanol.

Disclosed is a method for producing ethanol from xylose using recombinant Saccharomyces cerevisiae. In accordance with the method, NADH as a cofactor of xylose reductase required for the ethanol production, and NAD⁺ as a cofactor of xylitol dehydrogenase are coupled with each other and utilized, and acetaldehyde dehydrogenase mediating production of acetic acid as a byproduct is removed, and ethanol can thus be produced at a high yield and high production efficiency.

The invention discloses a method for producing xylitol through using xylose mother liquor or xylitol mother liquor depleted during the production of xylitol. The method comprises the following: 1 a step of adding hydrogen into arabinose separated from the xylose mother liquor to obtain D-arabitol or separating after adding hydrogen to obtain the D-arabitol; 2 a step of converting the D-arabitol obtained during the step 1 or the D-arabitol in the xylitol mother liquor into xylitol through making use of a strain simultaneously containing D-arabitol dehydrogenase and xylitol dehydrogenase; 3 a step of concentrating and crystallizing the xylitol conversion liquor obtained during the step 2 to obtain an xylitol product after removing thallus cells. The method which makes full use of the xylose mother liquor and xylitol mother liquor produced by a traditional method with simple and reasonable process can improve the utilization factor of raw materials such as corn cob and bagasse by about 9 to 14 percent, thereby greatly reducing the total production cost and consequently improving the economic efficiency of xylitol production.

The invention discloses a Saccharomyces cerevisiae engineering bacterium for performing alcohol fermentation by using xylose, and a preparation method and application thereof. The strain contains the following nucleotide sequences: xylose reductase gene, xylitol dehydrogenase gene and xylulokinase gene; and the xylulokinase gene is overexpressed. The preparation method comprises the following steps: integrating a constitutive strong promoter to the upstream of the xylulokinase gene of the Saccharomyces cerevisiae initial strain genome by homologous recombination to obtain a xylulokinase-overexpressed strain; and transforming into Candida lusitaniae to obtain xylose reductase gene and xylitol dehydrogenase gene, thereby obtaining the Saccharomyces cerevisiae engineering bacterium for performing alcohol fermentation by using xylose. The Saccharomyces cerevisiae engineering bacterium can grow by using the xylose as the unique carbon source, and lays foundation for the subsequent construction of alcohol production by xylose/glucose co-fermentation. The engineering strain can be further screened and transformed to produce alcohol from lignocellulose, thereby greatly lowering the alcohol production cost.

The invention relates to the field of microorganisms and molecular biology and in particular relates to a strain, a construction method thereof and fermentation application thereof. By taking a high-copy free type plasmid pYX212 as a carrier, xylose reductase (XR) and xylitol dehydrogenase (XDH) from candida pseudotropicalis are over-expressed in a saccharomyces cerevisiae strain, and the enzyme activity of the XDH is regulated through saccharomyces cerevisiae endogenous promoters TEF1 and PGK1, so that a recombinant saccharomyces cerevisiae strain capable of improving the consumption speed of xylose in joint utilization of the xylose and glucose can be obtained. According to the strain, the construction method thereof and the fermentation application thereof, molecular manipulation is simple and the joint utilization of the xylose and the glucose can be primarily realized without the need of a site-directed mutation or long-period evolution process.

Disclosed is a yeast strain of Candida utilis, wherein the yeast strain has been transformed with at least one of three genes that are operatively linked to a promoter sequence and encode polypeptides having activities of xylose reductase, xylitol dehydrogenase, and xylulose kinase. The yeast strain is useful for producing a metabolic product from xylose with high efficiency.

The invention discloses a yarrowia lipolytica genetically engineered bacterium for producing limonene. A method comprises the following steps: introducing an optimized xylose reductase gene XR, an optimized xylitol dehydrogenase gene XDH and an optimized xylose assimilation enzyme gene XK into chromosomes of uracil and leucine auxotrophic yarrowia lipolytica to construct a yarrowia lipolytica genetically engineered bacterium YBX06; transforming a recombinant vector containing two copy-optimized limonene synthase genes LS and one copy-optimized neroli diphosphate synthase 1 gene NDPS1 into theyarrowia lipolytica genetically engineered bacterium YBX06, and performing construction to obtain the yarrowia lipolytica genetically engineered bacterium YBX07. The yarrowia lipolytica genetically engineered bacterium constructed by the invention can utilize lignocellulose hydrolysate as a raw material and synchronously utilize xylose and glucose as a mixed carbon source to produce the limonene through biological fermentation, so that the yarrowia lipolytica genetically engineered bacterium has a good application prospect.

The present disclosure relates to host cells containing a recombinant xylose reductase, a recombinant cellodextrin transporter, a recombinant intracellular β-glucosidase, and lacking xylitol dehydrogenase and xylulokinase, and to methods of using such cells for producing xylitol from cellulosic biomass containing cellodextrin and xylose.