16 results about "Xylose Reductase" patented technology

The invention belongs to the technical field of biology, and particularly relates to a method for producing xylitol through two-step enzyme catalysis of hemicellulose hydrolysate, and the method comprises the following steps: taking hemicellulose hydrolysate as a raw material, adding arabinose dehydrogenase, NADH oxidase and coenzyme NADH, and carrying out first-step fermentation until no L-arabinose residue exists in fermentation liquor to obtain fermentation reaction liquor I; and adding xylose reductase and glucose dehydrogenase into the fermentation reaction liquid I, and carrying out second-step fermentation to obtain a fermentation product containing xylitol. According to the two-step enzyme catalysis method provided by the invention, xylitol is prepared, and high-purity xylose does not need to be used as a raw material; according to the present invention, the cheap hemicellulose hydrolysate can be directly adopted as the raw material, the xylose conversion rate and the xylitol yield can exceed 99%, the impurity arabitol content in the product is low, the other impurity saccharic acid is easy to separate, and the problems of complex process, large separation difficulty and high cost in the xylitol refining process are successfully solved.

The invention relates to the technical field of enzyme engineering, in particular to a xylose reductase XR21 mutant and application thereof. Specifically, the invention provides a novel xylose reductase mutant aiming at the defect of poorer thermal stability of the existing wild type xylose reductase, and particularly provides a xylose reductase mutant which is obtained by performing single or multiple site amino acid mutation on the 19th site, the 48th site, the 79th site, the 208th site and the 300th site of a xylose reductase sequence shown as SEQ ID NO: 2, compared with wild type xylose reductase, the obtained xylose reductase mutant has the advantages that the activity of catalyzing an epimer substrate arabinose into arabitol can be obviously reduced, and meanwhile, the selectivity to xylose is improved, so that the operation process of downstream separation and purification is simplified, and the biological catalysis requirement of green industry is met.

The invention relates to the technical field of enzyme engineering, in particular to a xylose reductase XR31 mutant and application thereof. Specifically, the invention provides a novel xylose reductase mutant aiming at the defect of poor thermal stability of the existing wild type xylose reductase (SEQ ID NO: 2), and particularly provides a xylose reductase mutant which is obtained by performing single or multiple site amino acid mutation on the 21st site, the 46th site, the 128th site, the 168th site and the 205th site of a xylose reductase sequence shown as SEQ ID NO: 2, compared with wild type xylose reductase, the obtained xylose reductase mutant has the advantages that the catalytic activity and the thermal stability on substrate xylose are obviously improved, the xylose reductase mutant can stably work under a high-temperature condition, and substrate conversion in industrial application is more efficiently realized.

The invention belongs to the technical field of biology, and particularly relates to a method for producing xylitol by catalyzing hemicellulose hydrolysate through a biological enzyme, which comprises two stages: in the first stage, adding hemicellulose hydrolysate, xylose reductase, arabinose dehydrogenase and glucose dehydrogenase to form a fermentation system, adjusting the pH value of the system to 8.0-9.5, and fermenting, adding L-arabinose until no L-arabinose residue exists in the fermentation liquid to obtain a fermentation reaction liquid I; in the second stage, the pH value of the fermentation reaction liquid I is adjusted to 6.5-7.5, fermentation continues to be conducted, and a fermented product containing xylitol is obtained. According to the method for preparing the xylitol through the biological enzyme catalysis method, cheap hemicellulose hydrolysate can be directly adopted as a raw material, and high-purity xylose does not need to be used as the raw material; the xylose reductase, the arabinose dehydrogenase and the glucose dehydrogenase used in the method are wide in gene source, the three-enzyme one-pot catalytic process is simple and efficient, the conversion rate of xylose and the yield of xylitol both can exceed 99%, the content of impurity arabitol in the product is low, other impurity saccharic acid is easy to separate, and the method is suitable for industrial production. The problems of complex process, high separation difficulty and high cost in the xylitol refining process are successfully solved.

The invention provides a strain for producing beta-carotene as well as a construction method and application of the strain, and belongs to the technical field of synthetic biology and genetic engineering. The construction method of the MYy107 strain disclosed by the invention comprises the following steps: step 1, integrating a mevalonate kinase gene ERG12, a phosphomevalonate kinase gene ERG8, a mevalonate diphosphate decarboxylase gene ERG19 and an isopentene diphosphate isomerase gene IDI1 on an RT08 bacterium, so as to obtain an RT10 strain; 2, a xylose reductase gene XYL1, a xylitol dehydrogenase gene XYL2, a xylose isomerase mutant XylA3 * and a xylulokinase gene Yl.Xk are integrated on the RT10 strain, and the MYy107 strain is obtained. According to the MYy107 strain constructed by the invention, the beta-carotene can be produced by using xylose and acetic acid at the same time, and the yield of the beta-carotene is remarkably improved and reaches 710.01 mg / L.

The invention discloses recombinant escherichia coli for producing D-tagatose by using redox enzyme driven by cofactor regeneration as well as a construction method and application of the recombinant escherichia coli, and belongs to the technical field of biological engineering. The method comprises the following steps: introducing xylose reductase xyrB, glucose dehydrogenase Gox2015, galactitol dehydrogenase RlGDH mutant T193G / G98C and water-producing NADH oxidase SpNox into escherichia coli, so as to construct recombinant escherichia coli; according to the method disclosed by the invention, a way for synthesizing the D-tagatose by regenerating and driving oxidoreductase through cofactors is designed and constructed, and lactose in whey can be completely converted into the D-tagatose and sodium gluconate by combining the way with beta-galactosidase, so that high-valued utilization of a dairy product processing by-product whey is realized.

The present invention belongs to the field of genetic engineering technology, specifically relating to genetically engineered bacteria and their use in xylitol production. The genetically engineered bacteria include a host cell and a xylose reductase gene and a xylose transporter gene inserted into the host cell. The present invention introduces the xylose transporter gene and the xylose reductase gene into Vibrio natriuresis. The resulting genetically engineered bacteria can functionally express and obtain a recombinant xylose transporter, thereby transporting extracellular xylose into the cell and converting the xylose into xylitol using the xylose reductase. This invention is the first to construct a genetically engineered Vibrio natriuresis bacterium capable of utilizing xylose and producing xylitol, which is of great significance for subsequent research on the use of Vibrio natriuresis in xylitol production.

The present invention relates to a genetically engineered erythritol strain and a construction method thereof, as well as application of the strain in preparing erythritol by microbial fermentation. The present invention introduces xylose reductase, xylitol dehydrogenase and xylitol kinase into Yarrowia lipolytica to reshape the xylose metabolic pathway, strengthens the expression of transketolase TKL1, transaldolase TAL and erythrose reductase ER in the erythritol bioproduction pathway, reduces the production of byproducts mannitol and arabitol by knocking out mannitol dehydrogenase MDH and arabitol dehydrogenase ArDH, reduces the conversion of erythritol into other substances by knocking out erythritol dehydrogenase EYD, weakens the accumulation of erythritol, strengthens the expression of sugar uptake pathway genes hexokinase HK and transporters Stp1 and Stp2, and finally produces a high-yield erythritol bacterium that can utilize a mixed carbon source of glucose and xylose, with the yield increased from 50.17 g / L to 195.56 g / L. This provides an excellent strain source for the industrial production of erythritol synthesized using xylose as a substrate, and has great industrial application potential.

The application discloses a genetically engineered bacillus subtilis for producing porphyra-334, a kind of bacteriosporin amino acid, and a construction method and application thereof, and belongs to the field of microbial metabolic engineering and synthetic biology.The strain takes bacillus subtilis WB600 as a starting bacterium: 1) a competitive pathway gene ywjH is knocked out to strengthen precursor supply;2) a gene cluster NlmysABCD derived from a porphea lincolnii is integrated in multiple copies to enhance pathway flux;3) sporulation genes spo0A and spoIIIE and threonine degradation gene tdh are knocked out to block byproduct generation and redistribute metabolic resources;4) xylose metabolism genes xylAB are introduced.The yield of porphyra-334 of the engineered bacterium reaches 3.38 g / L in shake flask fermentation, and the yield is increased to 15.1 g / L in 50 L fermenter fed-batch culture.

This invention discloses a strain for the efficient synthesis of D-tagatose, its preparation method, and its applications. Through strategies such as the discovery of novel galactitol dehydrogenase and promoter engineering, this invention initially increased tagatose yield by 28.48%. Simultaneously, a highly efficient and sensitive tagatose biosensor was developed, which was used as a screening tool for xylose reductase. Ss XR molecularly modified the strain to obtain the F128M-Q219K double mutant, which achieved a tagatose yield of 5.39 g / L in the producing strain. Based on this, amino acid complementation optimization was performed on the high-yielding strain, and the final engineered strain achieved a tagatose yield of 44.61 g / L in a 5 L bioreactor. This study provides a new strategy and core technology support for the efficient biosynthesis of tagatose.

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

This invention discloses a genetically engineered Bacillus subtilis strain for producing Mycosporine-glycine, its construction method, and its applications. Starting with Bacillus subtilis WB600, this strain significantly enhances Mycosporine-glycine synthesis by knocking out the competing pathway gene ywjH and expressing the AvmysABC gene cluster from Anabaena polymorpha at multiple sites. Further knocking out the sporulation genes spo0A and spoIIIE and introducing the xylose metabolism gene clusters xylA-xylB, combined with a mixed carbon source fermentation strategy, significantly increased the yield. The engineered strain achieved a Mycosporine-glycine yield of 3.64 g / L in shake-flask fermentation and 15.8 g / L in a 50 L fed-batch fermenter.

The present invention belongs to the field of biocatalysis, specifically relating to genetically engineered bacteria and their use in whole-cell catalysis of xylose to produce xylitol. The genetically engineered bacteria comprise a host cell, Vibrio natriuresis, and target genes inserted into the host cell. The host cell is Vibrio natriuresis; the target genes include xylose reductase and glucose dehydrogenase genes. The present invention introduces heterologous xylose reductase and glucose dehydrogenase genes into Vibrio natriuresis, and adjusts the gene dosage ratio of xylose reductase and glucose dehydrogenase through genomic integration to construct a genetically engineered Vibrio natriuresis. Compared to Escherichia coli, the whole-cell biocatalyst of the present invention has a shorter preparation cycle, higher catalytic activity, and higher production efficiency.

The application discloses a method for synchronously and efficiently metabolizing mixed sugar based on a Pichia pastoris mixed flora and application thereof. The Pichia pastoris mixed flora comprises at least one Pichia pastoris engineering strain for xylose metabolism and one Pichia pastoris engineering strain for oligosaccharide metabolism. By means of functional division of the strains, the interference of glucose signal on the xylose metabolic pathway is physically and genetically isolated, and the synchronous metabolism of xylose and cellulosic oligosaccharide is realized. The metabolic burden of each strain is reduced, the exclusive pathway of each strain can be optimized, the pathway competition and the imbalance of auxiliary factors are avoided, the overall fermentation rate and the sugar conversion rate are improved. The mixed flora system has a certain buffering capacity to environmental fluctuations and is more stable than a single strain. The strategy is particularly suitable for complex lignocellulose hydrolysate, and can effectively solve the problem of asynchronous utilization of multiple fermentable sugars in the lignocellulose hydrolysate and improve the total utilization rate of raw materials. In the process of simultaneous saccharification and fermentation of the mixed flora, the utilization rate of xylose and cellulosic oligosaccharide is improved, and the integrated biorefinery cycle is shortened.

The invention belongs to the technical field of microbial genetic engineering and industrial fermentation, and discloses an aspergillus niger engineering strain for producing L-malic acid by using xylose and a construction method and application of the aspergillus niger engineering strain. A three-gene recombination strain of an XR gene for coding xylose reductase, an XDH gene for coding xylitol dehydrogenase and an XK gene for coding xylulokinase through simultaneous overexpression is obtained through directional construction. Through synergistic overexpression of the XR gene, the XDH gene and the XK gene, the limitation that the starting strain LH-1 cannot utilize the xylose is successfully broken through, and effective utilization and directional conversion of the xylose are realized. The strain can be used for producing L-malic acid by using a low-cost xylose raw material, so that the production cost is remarkably reduced, a new technical path is provided for industrial production of organic acid, and the strain has a wide industrial application prospect.

The invention relates to the technical field of enzyme engineering, in particular to a xylose reductase XR34 mutant and application thereof. Specifically, the invention provides a novel xylose reductase mutant aiming at the defect of low enzyme activity of the existing wild type xylose reductase, and particularly provides a xylose reductase mutant which is obtained by carrying out single or multiple site amino acid mutation on the 48th site, the 111st site, the 219th site, the 306th site and the 309th site of the xylose reductase sequence shown as the amino acid sequence SEQ ID NO: 2, compared with wild type xylose reductase, the obtained xylose reductase mutant has remarkably improved catalytic activity on substrate xylose, so that the production cost of xylitol can be reduced, and a new strategy and a new method are provided for efficient production of xylitol.