39results about How to "Improve conversion yield" patented technology

The invention discloses recombinant bacillus subtilis producing micromolecular hyaluronic acid and belongs to the technical field of bioengineering. Hyaluronic synthase hasA originated from streptococcus zooepidemicus is integrated into bacillus subtilis to realize production of hyaluronic acid and meanwhile, overexpression on a synthetic route key gene of HA is carried out to realize high yield of HA in bacillus subtilis. On the basis, hyaluronidase originated from leeches is integrated into a bacillus subtilis genome for secretory expression subjected to a promoter Pgrac under induction control of IPTG (isopropyl-beta-d-thiogalactoside). Different micromolecular hyaluronic acid products with different molecular weights are prepared by controlling the secretory expression amount of hyaluronidase and induction starting time. The prepared products are different in ranges of molecular weights and the recombinant bacillus subtilis has important guiding reference meaning for direct production of micromolecular hyaluronic acid in a special particular range by microorganisms. The recombinant bacillus subtilis disclosed by the invention lays a certain foundation for efficiently preparing the micromolecular hyaluronic acid and is suitable for industrial production and application.

The invention discloses a method for preparing small-molecule oligomeric hyaluronic acid through an enzyme method, belonging to the technical field of bioengineering. According to the invention, by using hirudo-derived hyaluronidase, through hydrolysis of high-molecule hyaluronic acid, oligomeric hyaluronic acid having specific small molecular weights of tetrasaccharide, hexasaccharide, octasaccharide, decasaccharide and the like can be efficiently prepared. The method disclosed by the invention lays a certain foundation for efficient preparation of specific small-molecule oligomeric hyaluronic acid, and is applicable to industrial production.

The invention discloses a recombinant Pichia pastoris for producing small-molecular hyaluronic acids and a construction method thereof, belonging to the technical field of bioengineering. Hyaluronic acid synthase hasA derived from Streptococcus zooepidemicus and UDP-glucose dehydrogenase tuaD derived from Bacillus subtilis are expressed in recombinant Pichia pastoris GS115 host to implement production of hyaluronic acids. Meanwhile, hyaluronidase derived from hirudo is integrated to the Pichia pastoris genome and subjected to secretion expression by constitutive promoters with different intensities; the secretion expression level of the hyaluronidase is controlled to prepare small-molecular hyaluronic acid products with different molecular weights; and the prepared products have different ranges of molecular weight, and have instruction and reference meanings for directly producing small-molecular hyaluronic acids within a specified range from microbes. The recombinant Pichia pastoris lays certain foundation for high-efficiency preparation of small-molecular hyaluronic acids, and is suitable for industrial production.

Organosilicon compounds are prepared by the addition reaction of a gaseous unsaturated hydrocarbon with a silane or siloxane containing at least one silicon-bonded hydrogen atom in the presence of a hydrosilylation catalyst in a liquid reaction medium. In this process the unsaturated hydrocarbon and optionally the silane or siloxane is dispersed into the liquid reaction medium by a jet eductor (also known as a venturi pump) device and the resultant gas-in-liquid dispersion is introduced into a bubble reactor.

The invention discloses L-aspartase recombinant escherichia coli free of malic acid byproducts. The genes fumA, fumB and fumC of encoded fumarase in ammonium-tolerant escherichia coli BEW308 are inactivated, then encoded L-aspartase genes are inserted into the positions of encoded fumarase fumAC genes, and the L-aspartase recombinant escherichia coli free of the malic acid byproducts is obtained. The preservation number of a strain of the ammonium-tolerant escherichia coli BEW308 is CCTCC NO:M2013157. The invention further discloses a construction method and application of the strain. The constitutive high-activity expression of L-aspartase can be achieved, and cells or crude enzyme obtained after fermental cultivation has low fumarase activity.

In an integrated process for urea and melamine production, urea is produced in a urea plant (10) comprising a high pressure urea synthesis section (11) from which an aqueous solution comprising urea, ammonium carbamate and ammonia is obtained and a urea recovery section (21) operating at low pressure, and melamine is produced in a melamine plant (40) wherein off-gases resulting as by-products of the melamine synthesis are discharged from said plant at a medium pressure and recycled to the high-pressure urea synthesis section (11).

The invention relates to a preparation method of a vitamin B12 crude product. A process comprises the following steps: acidifying and hydrolyzing pseudomonas denitrificans, carrying out flocculent precipitation and filtering, and respectively collecting filter residues and filtrate; extracting the filter residues with an acetone composite solvent, mixing the extracted filter residues with the filtrate, and then performing macroporous resin adsorption, acetone aqueous solution desorption and vacuum concentration to obtain a concentrated solution; and performing converting with a cyanamide aqueous solution and crystallizing with acetone to obtain the vitamin B12 crude product. According to the method disclosed by the invention, cobamamide in fungus dregs is extracted by adopting a mixed solution consisting of acetone, isopropanol and water, so that the extraction yield can be effectively improved, the production operation coherence is high, and the generated wastewater amount is small; and cyandiamide is used as a transforming agent to replace sodium cyanide and potassium cyanide, VB12 hydrolysis is not easily caused in the transformation process, the transformation yield is good, the toxicity of the cyanamide is low, the safety and environmental protection pressure is reduced, and enterprises can safely and orderly carry out daily production and operation.

A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the step of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section.

Provided is a process for the preparation of certain 1,4-bicyclo[2.2.2]octane derivatives. The new synthetic procedure involves treating 1,4-dimethylene cyclohexane with an oxidizing agent in the presence of a transition metal catalyst to afford an oxo-substituted bicyclo[2.2.2]octane species. This intermediate structure can then be further derivatized. The processes of this disclosure thus affords a novel and simplified means for the commercial production of a wide variety of bicyclo[2.2.2]octane derivatives.

The invention discloses a method for preparing an aluminum scandium alloy through thermal reduction of scandium fluoride. The method comprises the following steps: filling the raw material scandium fluoride and the aluminum into a graphite crucible, putting in a vacuum reactor, vacuumizing to -0.1 MPa, degassing under a low temperature, keeping the vacuum degree, warming and melting the aluminum, heating to the temperature of 1100-1350 DEG C, continuously stirring, controlling the temperature till the surface of the melt is clear, reducing the temperature and casting to obtain the aluminum scandium alloy. The method for preparing the aluminum scandium alloy is a scandium fluoride vacuum aluminothermic reduction method; the prepared aluminum scandium alloy is high in scandium content, controllable in scandium element, high in scandium converting yield of greater than 95%, and low in fluorine content of less than 200 ppm and the byproduct can be comprehensively recovered.

The invention discloses a mycobacterium parafortuitum bacterial strain for efficient production of 4-HP. One classification of the mycobacterium parafortuitum bacterial strain is named as Mycobacterium parafortuitum BK12, and is deposited with the China Center for Type Culture Collection and assigned the accession number CCTCC No. M2017084. The bacterial strain is a new bacterial strain which is obtained through mutagenesis screening and can be efficiently converted to sterol for 4-HP production, a fermentation liquid taking 4-HP as a main product, subsequent separation and extraction steps are simplified, and good production stability is achieved. The invention further discloses a preparation method of high-yield 4-HP from the mycobacterium parafortuitum bacterial strain. According to the preparation method, as high as 3 parts of sterol in a fermentation medium is converted to 4-HP. When 3 parts of sterol is put in, the conversion rate reaches 90%, so that based on the guarantee of the single conversion rate, the single production yield is increased.

The invention belongs to the technical field of biomass utilization, energy and chemical engineering, and particularly relates to a multistage conversion process for inferior oil products. The multistage conversion process has the advantages that at least one type of iron oxide, desulfurization waste agents of the iron oxide or regeneration substances of the desulfurization waste agents of the iron oxide is used as catalysts, water-containing slurry is adopted, molar ratios of iron elements to sulfur elements in reaction systems are controlled, the fact that free radical condensation polymerization of the inferior oil products in pyrolysis procedures can be effectively blocked by means of carbonylation in the presence of CO is discovered, the CO and water can be converted and can be hydrogenated by active hydrogen, conversion reaction can be directly carried out on the inferior oil products during conversion reaction on the CO and the water, the liquefaction yield can be increased, anda large quantity of wastewater can be prevented after the conversion reaction is completely carried out.

A process for selective removal of a gaseous product (P) from a gaseous system comprising said product and other components (R1, R2), wherein the gaseous system is admitted to a first environment, which is separated from a second environment by a boundary wall, and a permeation membrane (3, 300) forms at least part of said boundary wall; a spatially non-uniform electric field (4) is generated between a first electrode or first plurality of electrodes (1, 301) located in the first environment and a second electrode or second plurality of electrodes (2, 302) located in the second environment, so that field lines of said non-uniform electric field cross said membrane, and a dielectrophoretic force generated on particles of said gaseous component (P) is at least part of a driving force of the permeation through said membrane, an amount of said product (P) being selectively removed from the first environment and collected in the second environment.

The invention discloses a conversion and separation method for cis-trans mixture of 4-isopropyl cyclohexanecarboxylic acid, and belongs to the technical field of chemical separation of fine chemical industry. The method includes the following process steps: mixing 4-isopropyl sodium cyclohexanecarboxylate hygrogenation liquid and an auxiliary agent; replacing nitrogen gas with air for a system, and holding the temperature and pressure after the temperature and pressure are raised to obtain conversion liquid; and extracting and crystallizing the conversion liquid. A cis-form is converted into atrans-form by the principle of chemical thermal stability under the action of the auxiliary agent. The conversion yield is high, more than 99% of the trans-form product is obtain after post-treatment, the operation is simple, the environmental pollution is less, and the conversion and separation method for cis-trans mixture of the 4-isopropyl cyclohexanecarboxylic acid is suitable for industrialproduction. Moreover, the cis-form in crystallization mother liquor is recycled and reused by the conversion reaction, the product yield is improved, and the production of ''three wastes'' is reduced.

The invention discloses a small molecule hyaluronic acid purification method. Small molecule hyaluronic acid is obtained by activated carbon treatment, tertiary alcohol precipitation, activated carbontreatment, centrifugation, rotary evaporation and freeze drying in order. The method is simple in reaction conditions. Furthermore, the method can further improve product purity, reduce impurities inproducts, and is suitable for industrial production.