407 results about "Whole cell" patented technology

The invention discloses a biosynthesis system for high-yield 1, 6-hexamethylenediamine and application of the biosynthesis system, and belongs to the technical field of biology. According to the method, key genes which are excavated and optimized in a 1, 6-hexamethylenediamine biosynthetic pathway are co-expressed in a single cell module or a multi-cell module, and different enzyme elements expressed by the cell module are subjected to enzyme cascade reaction, so that 1, 6-hexamethylenediamine can be efficiently synthesized by taking caprolactam or 6-aminocaproic acid as a substrate; furthermore, after the carboxylic acid reductase MaCAR is mutated, the catalytic activity of the carboxylic acid reductase MaCAR can be remarkably improved, and the yield of the 1, 6-hexamethylenediamine is further improved; in addition, the biosynthesis system disclosed by the invention directly takes the cell module as a whole-cell catalyst, and an enzyme purification step is avoided, so that the biosynthesis system has the advantage of low cost.

The invention discloses a method for efficiently synthesizing epiinositol by using a heat-resistant myo-inositol dehydrogenase mutant cascade system, and belongs to the field of biocatalysis engineering. Whole cells for expressing a scyllo-inositol dehydrogenase mutant and a heat-resistant scyllo-inositol dehydrogenase mutant are utilized to catalyze the scyllo-inositol to synthesize the epiinositol in a two-step cascade manner, and different from reported scyllo-inositol and D-chiral inositol synthesis methods, in the process of synthesizing the epiinositol by taking the scyllo-inositol as a substrate, the C4 position of the scyllo-inositol is dehydrogenated firstly, then the C4 position of the scyllo-inositol is dehydrogenated, and the C4 position of the D-chiral inositol According to the present invention, the structure of the substrate and the structure of the product are symmetric, and the enzyme is difficult to specifically recognize during the catalysis process, such that the synthesis of the different chiral compounds of the inositol is the important problem in the biological catalysis field. The invention provides a brand-new way for biocatalytically synthesizing the epiinositol, the yield of the epiinositol is increased to 1.89 g / L through enzyme modification, the conversion rate is 52.6%, and the yield and the conversion rate are the highest level reported publicly at present.

The invention discloses an arginine decarboxylase diaA enzyme mutant and application thereof in preparation of butanediamine, and belongs to the field of bioengineering. According to the invention, rational charge overturning transformation is simultaneously carried out on a pentamer meridian oligomeric interface and a dimer latitudinal oligomeric interface, so that stable assembly and efficient catalysis of the decamer under the condition of neutral to alkaline pH (7.0-9.0) are realized. Wherein positive charges are introduced into a meridian interface to weaken electrostatic repulsion, and negative charges are introduced into a latitudinal interface to enhance dimer compactness and substrate transfer efficiency. The specific enzyme activity of the representative double mutant AdiAD110K / H736E at pH 8.0 is about 35 times that of a wild type, and the representative double mutant AdiAD110K / H736E keeps a complete decamer state in a pH range of 7.0-9.0. The yield of butanediamine is up to 145.9 g / L under the whole-cell catalysis of the mutant.

The invention relates to a photovoltaic module, the photovoltaic module comprises three battery string groups which are connected in series, each battery string group comprises four battery strings which are connected in parallel, each battery string comprises a plurality of fragmented battery pieces, and each fragmented battery piece is a quarter piece formed by cutting a whole battery piece; the three battery string groups which are connected in series are distributed along a first direction, and a plurality of fragmented battery pieces in the battery strings are distributed along a second direction; the heads and the tails of the battery strings are connected with the bus bars, the bus bars comprise first bus bars located at the two ends of the photovoltaic module in the second direction and second bus bars located in the middle of the photovoltaic module in the second direction, and the first bus bars are located on the back face of the photovoltaic module. According to the photovoltaic module, on one hand, one half of the fragmented battery piece in the battery string is replaced by one fourth of the fragmented battery piece, and on the other hand, the photoelectric conversion efficiency of the photovoltaic module is relatively high by enabling the first bus bar to be located on the back surface of the photovoltaic module.

Provided are S-adenosylmethionine synthetase mutants and the use thereof, belonging to the technical field of biological enzyme engineering. Site-directed combinatorial mutations are performed on positions 189, 200, 234, 266 and 371 of S-adenosylmethionine synthetase MAT to obtain a series of mutants with improved enzyme activity, wherein the specific enzyme activity of I189V / V266H and V266H / N371R is increased by more than 10 times relative to the parent. The yields of S-adenosylmethionine synthesized by whole cells of recombinant bacteria expressing mutants I189V / V266H / N371R, V266H / Q234N / N371R and I189V / V266H / Q234N / N371R all reach 1550 mg / L or more. The provided enzyme mutants have broad application prospects in the production of S-adenosylmethionine and the construction of genetically engineered microorganisms for S-adenosylmethionine.

The invention discloses a high-efficiency lysine decarboxylase mutant and an application of the high-efficiency lysine decarboxylase mutant in synthesis of pentamethylene diamine. A series of mutants including a single mutant (such as N218G, T222V, C244P and the like), a double mutant and a three mutant are obtained by carrying out multi-site mutation on wild type lysine decarboxylase (SEQ ID NO.2) from Klebsiella grimontii. The catalytic efficiency of the mutant is remarkably improved, and the activity of the mutant is improved by 5.0-10.2 times compared with that of a wild type enzyme. According to the method disclosed by the invention, the substrate conversion rate of 99% or above can be realized within 2 hours through an optimized process of constructing an expression vector and a genetically engineered bacterium, inducing expression of lysine decarboxylase and synthesizing 1, 5-pentanediamine by utilizing a whole-cell catalysis technology. Compared with a traditional chemical method and a natural enzyme method, the method disclosed by the invention has the advantages of simplified process, high catalytic efficiency, low production cost and the like, and is suitable for producing bio-based 1, 5-pentamethylene diamine and nylon 56 salt.

The invention discloses a magnetic hydrogel coated bacterial biosensor platform and application, and belongs to the field of synthetic biology and clinical diagnosis. The hydrogel delivery and recovery system comprises a hydrogel-coated whole-cell biosensor and magnetic particles, the hydrogel is constructed by sodium alginate and calcium chloride, and the biosensor is a bacterium for sensing heme. More specifically, engineering bacteria YES601 and magnetic Fe3O4 particles are packaged by sodium alginate hydrogel to form magnetic hydrogel microspheres, the magnetic hydrogel microspheres are delivered to intestinal tracts as a biosensor and can sense heme to emit light, and then complete microspheres are efficiently recovered from excrement in a magnetic adsorption mode for detection. The intestinal bleeding detection efficiency and safety of the whole-cell biosensor are improved. According to the overall design optimization strategy of the hydrogel delivery and recovery system, the diagnosis efficiency and the practical application value can be improved.

The invention discloses a 4-hydroxyphenylacetic acid-3-hydroxylase mutant with improved activity and application thereof, the 4-hydroxyphenylacetic acid-3-hydroxylase mutant is obtained by mutating wild type 4HPA3H enzyme from Escherichia coli, the amino acid sequence of the wild type 4HPA3H enzyme is as shown in SEQ ID No.1, and the amino acid sequence is specifically mutated into any one of the following: (1) M205F; and (2) T398S. According to the present invention, the whole-cell catalysis activity of the 4-hydroxyphenylacetic acid-3-hydroxylase mutant, the M205F mutant and the T398S mutant on the p-hydroxyphenyllactic acid is improved by 1.70 times and 1.24 times compared with the WT;

A method of in situ point spread function (PSF) retrieval is disclosed which includes encoding 3D location of molecules into PSFs, receiving molecule-generated images containing PSFs, segmenting the images into sub-PSF, initializing template PSFs from a pupil function, determining a statistical measure of a predetermined function between the sub- and template PSFs, associating each of the sub-PSFs with a template PSF, aligning and averaging the sub-PSF, applying a phase retrieval algorithm to the averaged sub-PSFs to update the pupil function, regenerating the template PSFs, repeating until a difference between a new and a prior generation pupil function is below a predetermined threshold, generating in situ PSFs from the last pupil function, and applying a maximum likelihood estimation algorithm based on the in situ PSFs and the sub-PSF to thereby generate lateral and axial locations of molecules.

The invention discloses an ecDNA (ectodeoxyribonucleic acid) identification method based on scATAC-seq (scATAC-Seq) data. The ecDNA recognition method provided by the invention can be used for accurately detecting copy number amplification, breakpoint quantity and ecDNA feature quantity on the whole cell level. According to the method provided by the invention, the specific carried annular oncogene in the tumor can be identified, the distribution characteristics of the annular oncogene in the genome can be analyzed, and the overall composition of all annular DNAs in a single cell and the specific composition of the single annular DNA can be disclosed. In addition, according to the method, the existence of the circular DNA can be verified through a dyeing experiment, and the reliability of a detection result is ensured.

The invention relates to the technical field of bioengineering, and discloses a genetically engineered bacterium and a method for producing icaritin through whole-cell catalysis. By constructing double plasmids, choline kinase, isopentenyl phosphokinase, flavonoid 3-hydroxylase, flavonol synthase, isopentenyl transferase and oxymethyltransferase are simultaneously overexpressed in escherichia coli, so that a genetically engineered bacterium is constructed, and the engineering bacterium is used as a whole-cell catalyst to prepare a whole-cell engineering bacterium. The naringenin and the 3-methyl-2-butene-1-ol are used as substrates to be converted into the icaritin in a whole-cell catalysis mode, only one-step reaction is needed, the method is simple, rapid and high in efficiency, other chemical substances do not need to be additionally added in the conversion process, the cost is reduced, pollution to the environment is relieved, and the method is suitable for industrial production. And the biological production from low-price naringenin to high-added-value icaritin is realized.

The invention discloses a mutant with improved catalytic activity of S-adenosylmethionine synthetase and application of the mutant, and belongs to the technical field of biological enzyme engineering. According to the present invention, the site 189, the site 234, the site 266 and the site 371 of the S-adenosylmethionine synthetase MAT are subjected to site-specific combinatorial mutation to obtain a series of mutants with improved enzyme activity, the I189V / V266H improvement is the most obvious, and the specific enzyme activity is 3.5833 + / -0.1373 U.mg <-1 >, which is improved by 1353.08% compared to the parent WT; and for a whole-cell catalysis system, the yield of S-ademetionine synthesized by the mutant I189V / V266H / Q234N / N371R reaches 1751.01 mg / L, and the increase is most obvious. The enzyme mutant provided by the invention has a wide application prospect in the production of S-adenosylmethionine and the construction of genetic engineering microorganisms of S-adenosylmethionine.

The invention relates to the technical field of biological computing, in particular to a single-cell Hi-C atlas interpolation method and device, and the method comprises the steps: obtaining single-cell sequencing library data and a reference genome, determining the position of the sequencing data in the genome, and carrying out the statistics of the interaction frequency to obtain a Hi-C contact matrix; performing interpolation on the Hi-C contact matrix of any chromatin of the single cell according to similarity of adjacent nodes to obtain an adjacent node interpolation map of the single chromatin of the single cell; calculating an interpolation map of each chromatin of each cell, performing representation learning by taking the interpolation map as an adjacent matrix, splicing vectors to obtain a cell pre-embedded vector, and performing dimensionality reduction to obtain a whole cell embedded vector matrix; a cellular level similarity matrix is calculated by using a single cell embedded vector matrix and converted into a Markov probability transfer matrix, and the Markov probability transfer matrix is used for correcting an adjacent node interpolation map to obtain a Hi-C interpolation map, so that the interpolation accuracy is improved.

The invention provides an alpha-glucosidase mutant and application thereof in synthesis of alpha-arbutin, and the alpha-glucosidase mutant comprises the following steps: maltose and hydroquinone are taken as substrates, the recombinant bacteria are taken as a catalyst, catalytic reaction is carried out under a heating condition, and the alpha-arbutin is obtained. According to the synthesis method, maltose and hydroquinone are used as reaction substrates, and alpha-arbutin is generated through whole-cell catalysis; meanwhile, the sequence of the alpha-glucosidase mutant is integrated onto a pRSEDuet-1 expression vector and transferred into escherichia coli BL21 (DE3) for expression, a reaction system of recombinant bacteria is optimized, the optimal catalytic condition is determined, the yield of alpha-arbutin under the optimal condition is 24.8 g / L, the yield can reach 95.6% and is improved by 1.2 times compared with that of an original strain, and the alpha-glucosidase mutant has a good application prospect.

The invention discloses a method for separating and purifying gamma-aminobutyric acid from whole cells or enzymatic conversion liquid. The method comprises the following steps: removing thalli and large-particle impurities, denaturating, decolorizing and removing impurities, crystallizing for the first time, washing for the first time, crystallizing for the second time, washing for the second time and drying. According to the present invention, the thermal denaturation of the protein, the active carbon decoloration and the flocculation impurity removal are integrated, such that the solid-liquid separation frequency is reduced, the problems of difficult filtration and easy leakage of the powdered active carbon are solved, and the purity and the yield of the gamma-aminobutyric acid are significantly improved. In the whole separation and purification process, the pH value is not adjusted, the cost is saved, impurities are reduced, and the ion removal process is omitted. And collecting the primary crystallization mother liquor and washing liquor for secondary crystallization, so that the yield of the final product is greatly improved. According to the separation and purification method, the purity of the obtained gamma-aminobutyric acid is greater than 99%, the yield is greater than 92%, and the crystal light transmittance is greater than 99%. The method provided by the invention is simple, efficient and low in cost, and has a wide application prospect.

The invention relates to the technical field of gene engineering and recombinase catalysis engineering, in particular to a recombinant strain for expressing phenolic acid decarboxylase as well as a construction method and application of the recombinant strain. According to the invention, a recombinant strain for expressing the phenolic acid decarboxylase PADCs is constructed by heterologous expression of a coding gene PADCs of the phenolic acid decarboxylase. The enzyme liquid of the recombinant strain for expressing the phenolic acid decarboxylase has remarkable catalytic performance, p-coumaric acid can be used as a substrate, the recombinant strain is used for inducing expression, the purified enzyme liquid is used for catalyzing decarboxylation reaction of p-coumaric acid, and p-hydroxystyrene is synthesized; meanwhile, the phenolic acid decarboxylase PADCs has a wide substrate spectrum, the 4-vinylphenol compound can be used as a substrate, bicarbonate is used as a carboxyl source, the freeze-dried whole cell of the recombinant strain is utilized to catalyze the 4-vinylphenol compound to carry out regioselective beta-carboxylation reaction, a series of phenolic acids with biological activity are synthesized by an enzymic method, and meanwhile CO2 is immobilized; and a huge application potential is provided for the utilization of CO2.

The invention relates to L-threonine aldolase, in particular to an L-threonine aldolase mutant R318L / H128N / N90Q and application of the L-threonine aldolase mutant R318L / H128N / N90Q. The amino acid sequence of the L-threonine aldolase mutant is shown as SEQ ID NO: 3, and the L-threonine aldolase mutant is obtained by changing the 318th amino acid of L-threonine aldolase of which the amino acid sequence is SEQ ID NO: 1 into Leu from Arg, changing the 128th amino acid into Asn from His and changing the 90th amino acid into Gln from Asn. The mutant has high catalytic activity in a reaction of catalyzing benzaldehyde and derivatives thereof and glycine to synthesize beta-hydroxyl-alpha-amino acid, when a whole cell expressing R318L / H128N / N90Q is used for catalysis, the diastereoselectivity (de) of benzaldehyde and glycine to synthesize benzene serine is 65.8%, and the yield is 67.7%; the diastereoselectivity (de) of p-fluorobenzene serine synthesized from p-fluorobenzaldehyde and glycine is 77.5%, and the yield of p-fluorobenzene serine is 80.3%. The mutant has application potential in biosynthesis of beta-hydroxyl-alpha-amino acid.

The invention relates to the technical field of bioengineering, in particular to a system for producing valerolactam through whole-cell catalysis and application of the system. The system provided by the invention comprises L-lysine, and also comprises halomonas with the functions of synthesizing 5-aminovaleric acid, inhibiting GabT protein and enhancing beta-alanine coenzyme A transferase. According to the method, L-lysine is taken as a substrate, halomonas is utilized, 5-aminovaleric acid is synthesized firstly, degradation of the 5-aminovaleric acid is reduced by inhibiting the function of GabT protein in the halomonas, the function of beta-alanine coenzyme A transferase is enhanced, the metabolic flux from the 5-aminovaleric acid to the valerolactam is increased, and finally the valerolactam is efficiently produced.

The invention discloses a power semiconductor chip with a deep-energy-level acceptor impurity p base region and a manufacturing method, and belongs to the field of power semiconductor preparation. According to the power semiconductor device chip, deep energy level acceptor impurities are adopted in a p base region to form a p + base region covered by a whole cell, or additional deep energy level acceptor impurities are added on the basis of traditional p + base region doping to form the p + + base region covered by the whole cell; wherein the distance between the energy level position of the deep-energy-level acceptor impurity in silicon and the valence band top EV is more than 0.1 eV. Compared with a traditional power semiconductor device structure, the current turn-off capability of the IGCT device can be effectively improved, and the conduction voltage drop is obviously reduced compared with a traditional structure; the contradiction between the p + base region doping concentration of the IGCT and the current turn-off capability and the conduction voltage drop of the device can be improved.

The invention provides a plasmid, an alpha-ketoglutaric acid engineering strain and a construction method and application of the alpha-ketoglutaric acid engineering strain, the strain is obtained by adopting a directional transformation method, transcriptional levels of katE, katG, sodB and grxA genes are up-regulated, a catR gene and a katA gene are heterologously expressed, a high-copy plasmid pETKG is carried, and the plasmid simultaneously expresses L-glutamate oxidase LGOX genes from Streptomyces sp and Chain A; the strain self-synthesized catalase eliminates H2O2 generated in the process of producing alpha-ketoglutaric acid through enzyme catalysis, engineering bacteria of L-glutamate oxidase LGOX expressed by pETKG plasmids are used for performing whole-cell catalysis on L-sodium glutamate to synthesize alpha-ketoglutaric acid, and the engineering strain is a high-level engineering strain capable of industrially and stably producing alpha-ketoglutaric acid.

The invention provides an application of inositol monophosphate in an enzyme catalysis reaction system for preparing inositol. The invention also provides a preparation method of the inositol, the starch is used as a substrate, glucan phosphorylase, glucose phosphate mutase, inositol-3-phosphate synthase and inositol monophosphate are added as enzyme catalysts to catalyze the substrate to generate the inositol, the inositol monophosphate is derived from Archaeoglobus fulgidus, the amino acid sequence is shown as SEQ ID NO: 12, or the amino acid sequence is shown as SEQ ID NO: 1, or the amino acid sequence is shown as SEQ ID NO: 2, or the amino acid sequence is shown as SEQ ID NO: 3, or the amino acid sequence is shown as SEQ ID NO: 4, or the amino acid sequence is shown as SEQ ID NO: 5, or the amino acid sequence is shown as SEQ ID NO: 6. The inositol monophosphate is derived from Thermococcus kodakarensis, and the amino acid sequence of the inositol monophosphate is as shown in SEQ ID NO: 13; or the inositol monophosphate is derived from Pseudothermotoga lettinae, and the amino acid sequence of the inositol monophosphate is as shown in SEQ ID NO: 14. Inositol-3-phosphate synthetase and inositol monophosphate with good performance are screened, high-concentration starch is efficiently catalyzed to be converted into inositol by a one-pot method in a whole-cell feeding mode, and NAD < + > and other coenzymes do not need to be used. Under a 60L reaction system, 200g / L of corn starch is catalyzed, the unit yield of the prepared inositol reaches 161g / L, and the method has a good industrial application prospect.

The invention is based on the deletion of 21 amino acids from the C-terminal region of the S2 subunit of SARS-CoV2-S protein and transporting the Si subunit, which is fused to S2 to the cell membranes. In this way, the presentation of the antigenic S1 subunit of SARS-CoV2-S protein in large amounts and in its natural structure in the cell membrane and its use as a whole cell or cell membrane has been determined as a new vaccination protocol for the SARS-CoV-2. Designing the S2 subunit of SARS-CoV2-S protein as a carrier, fusing any bacterial, viral, and tumor proteins with antigenic properties and transporting it to the cell membrane will be a comprehensive vaccination protocol that will cover all bacteria, viruses and even tumors.

The invention relates to the technical field of agricultural biology, in particular to a fusion P450 enzyme mutant, a method for improving VD3 catalytic activity and a method for generating 25 (OH) VD3 through whole cells. The invention constructs a fusion P450 enzyme VK1-CYP116B46-L21 and a self-sufficiency fusion P450 enzyme mutant with improved activity, wherein the self-sufficiency fusion P450 enzyme mutant is used for catalyzing vitamin D3 to synthesize calcifediol; vD3 is taken as a substrate, glucose, a cosolvent and a wet thallus induced by recombinant escherichia coli for simultaneously expressing fusion P450 enzyme and glucose dehydrogenase are added, and the highest yield of 25 (OH) VD3 within 24 hours after catalytic reaction can reach 3.26 g / L; whole cells are directly used as a catalyst, enzyme purification is not needed, glucose dehydrogenase is introduced, and glucose is used as a substrate to regenerate a cofactor NAD (P) H, so that addition of expensive cofactors is avoided, the production cost is reduced, and industrial production is facilitated.

The invention discloses ethanol dehydrogenase, recombinant genetically engineered bacteria and application of the ethanol dehydrogenase in asymmetric reduction of prochiral carbonyl compounds, the ethanol dehydrogenase has good biological performance, heterologous expression in Escherichia coli engineering bacteria is achieved, intracellular coenzyme can be directly utilized when whole cells are adopted as a catalyst, and the catalyst has a good application prospect. Zero addition of the coenzyme is realized, the enzyme has the advantages of high activity, high stereoselectivity, wider substrate spectrum and the like, prochiral ketone compounds can be greenly and efficiently catalyzed to be converted into corresponding chiral alcohols, and the problems of low conversion rate, low yield, low e.e. Value, complex reaction process, more byproducts and the like in a traditional chemical method are solved. The ethanol dehydrogenase has good tolerance to isopropanol, and the isopropanol can be used as a hydrogen source to realize the circulation of coenzyme. And the byproduct acetone generated by the enzyme catalytic reaction and the isopropanol remaining in the reaction can be separated and recovered by a technical means, so that the production cost is greatly reduced.

The invention provides a photovoltaic module and a photovoltaic system. The photovoltaic module comprises a first bypass module, and a first battery string group and a second battery string group which are connected in parallel; each of the first battery string group and the second battery string group comprises two battery strings which are connected in parallel, each battery string comprises a plurality of quartered battery pieces which are connected in series, and each quartered battery piece is a quarter battery piece formed by cutting a whole battery piece; the photovoltaic module also comprises a second bypass module, and a first battery unit and a second battery unit which are connected in parallel. The first end of the first battery unit and the first end of the second battery unit are both connected with the output end of the second bypass module, and the second end of the first battery unit and the second end of the second battery unit are both connected with the input end of the second bypass module. According to the photovoltaic module provided by the embodiment of the invention, the battery piece is arranged to be the quarter battery piece formed by cutting the whole battery piece, so that the internal power loss of the battery piece can be reduced, and the output power of the photovoltaic module can be improved.

The utility model discloses a liquid circulation module to solve the problems that an existing cell culture device cannot accurately simulate an in-vivo dynamic circulation process, cross contamination occurs in a conventional cell culture experiment process, and an experiment result is inaccurate. The system comprises two liquid storage tanks, two pressure pumps and a cell culture device which is matched with the two liquid storage tanks for use, during use, liquid is driven by the pressure pump to flow, so that the liquid flows from the first liquid storage tank to the second liquid storage tank after passing through the flowmeter, the cell culture device and the one-way valve according to a set flow rate, liquid is quickly supplemented from the second liquid storage tank to the first liquid storage tank after being cultured for a period of time, and the process is repeated, so that the long-term dynamic circulating culture process of cells is realized; the device is simple in overall structure and convenient to use, the in-vivo dynamic circulation process can be accurately simulated in the cell culture process, cross contamination in the conventional cell culture experiment process is avoided, and therefore the accuracy of the experiment result is improved; the whole cell culture process is in a sealed state, so that the pollution problem is avoided.

The invention discloses a method for producing MK-7 through whole-cell regulation and control by using different time sequence type promoters, recombinant escherichia coli and application. According to the method, the time sequence type promoters are used for regulating and controlling expression of different key genes related to MK-7 synthesis. According to the invention, the time sequence promoter is used for whole-cell regulation and control to produce the vitamin MK-7 for the first time, dynamic regulation of the MK-7 is realized, and the production efficiency of the MK-7 can be remarkably improved by accurately regulating and controlling expression of key genes in a synthesis route of the MK-7 and optimizing an intracellular metabolic process. The promoter disclosed by the invention can regulate cell metabolism and enhance synthesis of MK-7 in different growth stages or under different environmental conditions by controlling the time and strength of gene expression. The MK-7 is produced by adopting the constructed recombinant escherichia coli obtained based on whole-cell regulation of the sequential promoter, and the yield of 14 g / L can be finally achieved in a 5L fermentation tank.

The invention discloses a method for preparing butanediamine and spermidine from whole cells, and belongs to the field of bioengineering. According to a rational copolymerization modification strategy, a meridian interface and a latitudinal channel interface of arginine decarboxylase are subjected to rational modification respectively or simultaneously, and a series of mutants are obtained. The optimal mutant AdiA H729D / E467K / H736E, which is subjected to double-interface synergistic modification, disclosed by the invention, keeps high activity in the whole neutral-alkaline range of pH (Potential of Hydrogen) of 7.0 to 9.0. The optimal pH of the arginine decarboxylase mutant is increased, the enzyme activity stability in a neutral pH range is improved, the arginine decarboxylase mutant is more suitable for the condition requirements of industrial microbial fermentation, and a foundation is laid for efficient synthesis of butanediamine. The spermidine yield is up to 153.3 mg / L by using the mutant to catalyze the whole cell.

The invention discloses a screening method for a riboswitch capable of specifically recognizing doxycycline as well as rational transformation and application of the riboswitch, and belongs to the field of gene expression regulation and control. The invention provides a doxycycline specific riboswitch, establishes a high-throughput screening method based on a flow cytometry, and obtains the doxycycline riboswitch with further improved activation multiple by means of computer-aided prediction of binding sites of the riboswitch and calculation of mutation sites. According to a dose reaction curve, the riboswitch shows linear correlation at 40-100 [mu] g / L, and meanwhile, the constructed whole-cell sensor is low in price, high in stability and simple to operate, and can be used for on-site rapid detection.

The invention discloses a separation and preparation method of scyllo-inositol, and relates to the technical field of scyllo-inositol production, myo-inositol solution is added into whole-cell wet thalli containing inositol dehydrogenase and scyllo-inositol dehydrogenase, conversion is carried out in PBS buffer solution to obtain conversion liquid, the conversion liquid is filtered and decolorized by a ceramic membrane and an ultrafiltration membrane, and the scyllo-inositol is obtained. Then concentrating and centrifuging to obtain a mixed crude product of scyllo-inositol and inositol, pulping and washing with purified water, and drying a wet product to obtain scyllo-inositol. In the separation and preparation process, boric acid, strong acid, strong alkali and organic solvent are not used, precipitation of composite salt is not needed, the process steps are reduced, the environment is not polluted, the operation is safe, the recovery cost is low, materials are recycled, a complex recovery system is not needed, the cost can be better reduced, and the method is environment-friendly.