47 results about "Xylose metabolism" patented technology

A strain of xylose-utilizing Zymomonas was engineered with a genetic modification to the glucose-fructose oxidoreductase gene resulting in reduced expression of GFOR enzyme activity. The engineered strain exhibits reduced production of xylitol, a detrimental by-product of xylose metabolism. It also consumes more xylose and produces more ethanol during mixed sugar fermentation under process-relevant conditions.

The invention discloses recombinant zymomonas mobilis capable of producing ethanol by using xylose and a fermentation method thereof. The recombinant zymomonas mobilis GX1 capable of producing the ethanol by using the xylose is preserved in China General Microbiological Culture Collection Center, and has a preservation number of CGMCC 3438. The controlling elements of Escherichia coli rrnB and related genes of xylose metabolism are fused to build plasmids with artificially fused operons for the first time; and recombinant zymomonas mobilis strains capable of producing the ethanol by using the xylose are obtained through a method of electrotransformation and acclimatization. The recombinant zymomonas mobilis can efficiently express exogenous genes, can efficiently produce the ethanol by using glucose and the xylose to ferment together at the temperature of between 30 and 34 DEG C, and can produce the ethanol by using corncob hydrolysate containing the xylose and the glucose. The strains have important significance for producing clean energy by effectively using waste lignocellulose and solving the current energy crisis.

Provided is a construction method of an escherichia coli genetically engineered bacteria producing succinic acid by xylose metabolism and the method for producing succinic acid by fermentation using the bacteria. The ATP biosynthesis pathway of escherichia coli is modified by means of molecular biology and the enzyme activity related to the pathway is over-expressed; thus the total ATP amount within escherichia coli cells is effectively increased such that the recombinant escherichia coli is able to grow using xylose metabolism, and the succinic acid synthesis efficiency is thereby significantly improved.

The invention utilizes cloning and transformation techniques in combination with mutation and strain taming techniques to obtain yeasts having high xylose consumption rate and ethanol yield. The cloning and transformation used in the invention are to transform xylose metabolism genes to yeasts to solve the problem that some yeast strains cannot utilize xylose to produce ethanol. The mutation and strain taming used in the invention are to increase xylose consumption rate and ethanol yield to solve the problem of low rate and yield. By combining the above-mentioned technical means, the invention unexpectedly obtain a mutant having high xylose consumption rate and ethanol yield.

The invention relates to a method for the biotechnological production of xylitol, in which micro-organisms capable of metabolizing xylose to xylitol are used by modifying micro-organisms such that oxidation of NADH by enzymes other than the xylose reductase is reduced or excluded, cultivating the micro-organisms in a substrate containing xylose and 10-40 grams per liter of sulfite salt, and enriching the xylitol and recovering it from the substrate.

The invention discloses a wide host plasmid carrying xylose metabolism related genes and construction method thereof, belonging to the field of molecular biology techniques. The plasmid contains four xylose metabolism related enzyme genes, xylose isomerase (xylA), xylulokinase (xylB), transaldolase (talA) and transketolase (tktA), which are derived from E.coli DH5alpaha strain. The plasmid construction method uses the Gateway technology, to respectively design specific primers of four target genes xylA, xylB, talA and tktA, takes the E.coli DH5alpaha strain as the origin stain of the target genes to amplify the corresponding gene through the PCR; the PCR product performs BP recombination with the corresponding pDONR vector, and then the obtained Entry clones perform LR recombination with the pDEST14, to obtain the pDEST14-ABAT plasmid; the pDEST14-ABAT plasmid is connected to the Xha I single zyme cutting vector pBBR1MCS2 through the Xba I and Nhe I double zyme cutting product to obtained the recombinant plasmid pBBR1MCS2-ABAT. The superior strain shifted in the plasmid can greatly reduce production costs of cellulosic ethanol.

The invention uses Kluyveromyces marxianus yeast as a platform to construct a strain of knockout pyruvate decarboxylase and glycerol-3-phosphate dehydrogenase by means of genetic engineering, metabolic engineering, molecular biology and synthetic biology. The strain's growth is restored by metabolic regulation in order to improve the yield and production rate of pyruvate, and then the strain's xylose metabolism is improved, so that it has the ability to produce pyruvate with xylose. Eventually the glucose effect of the engineering strain is removed so that the engineered strain is capable of simultaneously saccharifying lignocellulose, using glucose and xylose and fermenting at high temperature to produce pyruvate. The Kluyveromyces marxianus strain YZB058 obtained by the present invention can produce pyruvate at the same time using glucose and xylose at 42 DEG C. At 42 DEG C, YZB058 is able to produce 29.21 g/l of pyruvate with 40.97 g/l of glucose and 20.37 g/l of xylose for 36 h, the production rate is at a rate of 0.81 g/l/h, and the total yield is at 0.48 g/g.

The invention relates to a genetic engineering strain for regulating expression activity of GRE3 genes in saccharomyces cerevisiae 1308-P. According to the invention, it discovers that the GRE3 genes in the saccharomyces cerevisiae can induce the generation of a by-product, namely xylitol, from xylose metabolism, and the generation of the xylitol is related to tolerance in a xylose fermenting process. It also discovers that the GRE3 genes, which are although negative regulator genes, cannot be completely knocked out. Experiments prove that the engineering strain, which is obtained by knocking out one of the GRE3 genes in the 1308-P, can improve the efficiency of fermenting ethanol by virtue of the xylose and reduce the generation of the by-product, namely the xylitol. Moreover, the modified bacterium also has the advantages that the original glucose utilization rate of an original strain, an inhibitor is high in tolerance and the like.

The invention discloses a method for promoting microbial cells to transport and / or hydrolyze xylo oligosaccharides and application thereof. Experiments prove that cello-oligosaccharide transport protein CDT-2 also has xylo-oligosaccharide transport capacity, beta xylosidase GH43-2 has hydrolysis effect on the xylo-oligosaccharides, according to the method, cdt-2 gene and / or gh43-2 gene are/ is introduced into a microbial strain to obtain a recombinant microbial strain, and compared with a starting strain, the recombinant microbial strain acquires or improves the capability for transporting the xylo-oligosaccharides from extracellular to intracellular and / or hydrolyzing the xylo-oligosaccharides into xylose. By discovery of the xylo-oligosaccharide transport protein CDT-2 and application of the beta xylosidase GH43-2, an idea using modified yeast to directly use the xylo-oligosaccharides derived from hemicellulose degradation for producing biological chemicals is provided, co-fermentation of glucose, xylose, cello-oligosaccharide and xylo-oligosaccharide mixed sugar can be realized by co expression of cdt-2 and gh43-2 and cdt-1 and gh43-1 in brewer's yeast containing xylose metabolic pathway to produce the biological chemicals, and the production cost is greatly saved.

The invention provides a breeding method specific to lactobacillus capable of utilizing xylose. In the method, according to the characteristic that mesophilic lactobacillus with xylose metabolism capability can utilize the xylose but is not resistant to high temperature, the characteristic, of which utilizes the xylose, of the mesophilic lactobacillus is used as a genetic marker. Lactobacillus capable of tolerating high temperature but not utilizing the xylose is selected, and the high-temperature tolerance of the lactobacillus is utilized to serve as the genetic marker for the lactobacillus. Under an appropriate condition, protoplasts of two parents are prepared and fused. High temperature and the xylose are utilized as screening pressure so as to regenerate a fusant of the two parents under the appropriate condition, and thus, a fusant capable of utilizing the xylose and resisting certain high temperature is obtained finally. The fusant obtained by using the method can utilize 40g/l glucose and xylose at the temperature of 45 DEG C respectively, and the yield of the lactic acid can reach 25.14g/l and 20.96g/l.

The invention discloses a brewing yeast strain capable of metabolizing xylose. The strain is a brewing yeast (Saccharomyces cerevisiae) BSHH02B, and is preserved in the China General Microbiological Culture Collection Center (CGMCC) on Feb. 8th, 2012, wherein the preservation number is CGMCC No. 5747. The strain carries a unique xylose metabolizing way, i.e. a molecular xylose generates a molecular pyruvic acid and a molecular glycolaldehyde through two mesostate, i.e. xylonic acid and 3-deoxyl-D-glycerol-ketopentose acid. By the xylose metabolizing way, the brewing yeast BSHH02B can quickly grow by using the xylose under an aerobic condition, and can be applied to the production of chemical products by using xylose-containing raw materials, wherein the chemical products include ethanol, glycol, carboxylic acid and the like.

The invention relates to the field of biological preparation of ethanol, in particular to an industrial strain and a method for efficient xylose metabolism based ethanol production. The preservation number of the industrial strain is CGMCC No.15568. The gene expression clusters of an XR gene of xylose reductase, an XDH gene of xylitol dehydrogenase, an XK gene of xylulokinase, two copies of xylose transporter genes mgt05196, TAL1 and 2 copies of PYK1 genes are integrated into Saccharomyces cerevisiae by a constitutive strong promoter, and accordingly, glucose metabolism and xylose metabolismof Saccharomyces cerevisiae are improved, and ethanol production is increased.

Provided herein are non-naturally occurring microbial organisms having increased xylose metabolism and increased production of ethanol using xylose as a substrate, as well as methods to make and use these microbial organisms to produce ethanol.