The invention discloses a method for enzymatically preparing galacto-mannan-oligosaccharides from sesbania cannabina. Directly mechanically crushed sesbania cannabina seeds are taken as enzymolysis substrates. The method specifically comprises the following steps of (1) air-drying the sesbania cannabina seeds, and crushing the sesbania cannabina seeds into 20 to 100 meshes; (2) mixing the crushed sesbania cannabina seeds and beta-mannase with low beta-mannase activity, adding water, adding a pH buffer solution or acid and alkali, mixing until the solid-liquid weight rate is 1:(3-50), controlling the pH value to be 4 to 6, and performing reaction for more than 12h under the condition of 45 to 55 DEG C, wherein the using amount of the beta-mannase for every gram of galactomannan in a reaction system is 10 to 100U; (3) treating a hydrolysate for 10min at 100 DEG C to deactivate the beta-mannase after enzymatic hydrolysis reaction is finished; (4) performing solid and liquid separation on the hydrolysate to obtain clear liquid which is a galacto-mannan-oligosaccharide solution. The method has the advantages of simple process, favourability for increasing the concentrations of the substrates and a product of enzymatic reaction and reducing the stirring energy consumption of the enzymatic hydrolysis reaction, and the like.

Method for enzymatically preparing galacto-mannan-oligosaccharides from sesbania cannabina

The invention discloses a leucine dehydrogenase mutant, a coding gene, a recombinant vector, a gene engineering bacterium and application thereof. The recombinant Escherichia coli strain with efficiently expressed leucine dehydrogenase has the advantages of high yield, simple technique and the like, is convenient for industrialized application, and can be directly used for producing L-2-aminobutyric acid. After the LeuDH-Q358T mutant fermentation finishes, the total enzyme activity for 2-ketobutyric acid at 35 DEG C is up to 965.7 U/g, and the conversion rate of 2-ketobutyric acid is up to 99%, thereby providing favorable technical supports for large-scale production of L-2-aminobutyric acid.

Leucine dehydrogenase mutant, coding gene, vector, engineering bacterium and application thereof

The invention discloses a method for preparing nano cellulose by utilizing plant fibers pretreated by neutral sulfite The method comprises the following steps: pre-treating the crushed plant fibers with a neutral bisulfite solution, reserving the plant fibers via solid-liquid separation, washing and removing degradation products of the plant fibers in the pretreatment process; performing oxidation treatment on the plant fibers with an oxidation system, then repeatedly centrifuging and washing to obtain oxidized plant fibers; performing cyclic homogenate treatment and ultrasonic treatment on the oxidized plant fibers, centrifuging and collecting an supernatant, namely nano fiber dispersion liquid; performing freezing and drying treatment on the nano fiber dispersion liquid to obtain the nano cellulose The method disclosed by the invention has the benefits that the nano cellulose is prepared by utilizing the plant fibers pretreated by the neutral sulfite, raw materials are not required to remove hemi-cellulose and lignin step by step, the production process is simple, the cost is low, the environment is protected, the cellulose purity of the pretreated plant fibers is high, and the prepared nano cellulose is high in stability and modulus; therefore, the industrial application prospect is huger

Method for preparing nano cellulose by utilizing neutral sulfite pretreatment plant fibers

The invention discloses one group of leucine dehydrogenase as well as encoding gene and application thereof. According to the invention, one group of mutant protein is provided firstly, and is any one of the following (a1) to (a8): (a) a mutant protein 3 shown in a sequence 5; (a2) a mutant protein 11 shown in a sequence 7; (a3) a mutant protein 14 shown in a sequence 9; (a4) a mutant protein 15 shown in a sequence 11; (a5) a mutant protein 19 shown in a sequence 13; (a6) a mutant protein 20 shown in a sequence 15; (a7) a mutant protein 25 shown in a sequence 17; (a8) a mutant protein 26 shown in a sequence 19. According to the mutant proteins provided by the invention, the catalytic efficiency is obviously higher than that of the existing leucine dehydrogenase, and the reaction time under a condition that TMP consumption rate is equal to 99% is shorter than that of the existing leucine dehydrogenase, particularly the mutant protein 3. The mutant protein has a great application value in production of L-tertiary leucine, and very considerable economic benefit can be produced.

One group of leucine dehydrogenase as well as encoding gene and application thereof

The invention provides a method for preparing furfural and xylose. The method comprises the steps that a xylogen raw material is subjected to acidolysis under the action of a catalyzer, so that liquid glucose is obtained, wherein the catalyzer comprises non-oxidized acid and sulfite, the non-oxidized acid comprises first non-oxidized acid and second non-oxidized acid, and the first non-oxidized acid is sulphurous acid; the dehydration reaction is conducted on the liquid glucose, so that furfural is obtained. According to the method for preparing furfural and xylose, the compatibility of the specific non-oxidized acid and the sulfite is taken as the catalyzer, in this way, hydrolyzation can be conducted on the xylogen raw material more sufficiently, post-hydrolyzation is not needed in the whole furfural preparing process, the reaction steps are simpler, and scaling is avoided.

Method for preparing furfural and xylose

Method for preparing xylooligosaccharide by treating plant fibers via neutral sulfite

The invention discloses high-temperature resistant recombined beta-mannase and the application of the high-temperature resistant recombined beta-mannase. A beta-mannase gene from aspergillus niger is cloned to a pichia pastoris expression vector pPICZ alpha A and converted into pichia pastoris KM71H so that the recombined beta-mannase with high expression quantity can be obtained, wherein the beta-mannase gene is optimized according to the preference of the pichia pastoris codon. The optimum temperature of the recombined beta-mannase is 80 DEG C. The beta-mannase is applied to enzymolysis konjac powder for producing mannan oligosaccharide, the concentration of a substrate is high, the yield of products is high, the reaction time is short, the conversion rate is high and the high-temperature resistant recombined beta-mannase has high industrial potential productivity and application value.

High-temperature resistant recombined beta-mannase and application thereof

The invention discloses a leucine dehydrogenase with an amino acid sequence shown in SEQ ID No.2 and a gene for coding the leucine dehydrogenase, and provides a novel dehydrogenase with a source different from that of a currently known leucine dehydrogenase. A leucine dehydrogenase gene ldh is cloned on the basis of a bacillus coagulans genome, has an amino acid sequence shown in SEQ ID No.1, and is used for coding the leucine dehydrogenase. The leucine dehydrogenase has very large advantages in preparation of optical pure amino acid and derivatives of the optical pure amino acid by catalytic asymmetric reduction of carbonyl. Meanwhile, the invention further provides a method for preparing, separating and purifying recombinant plasmids and recombinant bacteria with heat-resistant leucine dehydrogenase activity.

Leucine dehydrogenase and gene for coding same

The invention discloses corn phenylalanine ammonia enzyme. The amino acid sequence of the corn phenylalanine ammonia enzyme is shown as SEQ ID NO:2, and the nucleotide sequence of the corn phenylalanine ammonia enzyme is shown as SEQ ID NO:1. The invention further discloses the application of the corn phenylalanine ammonia enzyme in synthesis of cinnamic acid through a biological method. A corn phenylalanine ammonia enzyme ZmPAL gene is constructed to an escherichia coli expression vector and converted to escherichia coli cells to carry out prokaryotic expression, and can be used for production of high-specific-activity plant phenylalnine ammonialyase. The obtained recombined corn phenylalanine ammonia enzyme can catalyze L-phenylalanine to remove amidogens to produce the cinnamic acid, provide the possibility of preparing the cinnamic acid through biosynthesis, and have high industrial application value.

Corn phenylalanine ammonia enzyme and application thereof

The invention discloses a method for selectively utilizing cinnamic acid in phenylalanine bioconversion broth and cyclically utilizing conversion broth. The method comprises the following steps: performing solid-liquid separation on a phenylalanine bioconversion broth to respectively obtain a clear liquid I and cell thallus; regulating the pH value of the clear liquid I to 4.5 with acid, and stirring the clear liquid I at room temperature until white precipitate is separated; performing solid-liquid separation on the mixed system to obtain a clear liquid II and precipitation, and performing washing and freeze-drying on the precipitation to obtain a cinnamic acid sample; and regulating the pH value of the clear liquid II to the value required by bioconversion with alkali, mixing the clear liquid II with the cell thallus, and continuously performing bioconversion to prepare the cinnamic acid. By adopting the method, the method can be used for reducing the inhibition effect of a primer and cyclically utilizing the conversion broth and cells, the yield is up to 95 percent, and the product purity is up to over 98 percent. The method is simple and easy in process, and can be used for greatly reducing the extraction cost and realizing multiple times of cyclic utilization of resting cells and conversion broth.

Method for selectively separating cinnamic acid in phenylalanine bioconversion broth and cyclically utilizing conversion broth

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