83 results about "Exogenous enzymes" patented technology

The invention discloses a yeast beta-glucan preparation method based on high pressure-microjet homogenization treatment, and belongs to the technical field of zymosan extraction. The method comprises the following steps: carrying out high pressure-microjet homogenization pretreatment on active dry yeast, then carrying out autolysis treatment, then extracting beta-glucan by an acid-alkali method, and finally carrying out freeze drying to obtain a high-purity product. The core of the method is that the yeast cell walls are subjected to physical wall breaking by adopting a high pressure-microjet homogenization technology, and the extraction rate and the purity of the beta-glucan are remarkably improved by combining with an optimized acid-alkali treatment process. Compared with a traditional enzymolysis method, the method has the advantages that damage of exogenous enzyme to the beta-glucan structure is avoided, the purity of the obtained product reaches 84% or above, the content of protein impurities is lower than 0.2%, a new way is provided for efficient utilization of yeast cell wall resources, and the method is suitable for the fields of food, medicine and health care products.

The invention relates to a preparation method of a double-bacterium fermented opuntia ficus-indica fermentation extract and application of the double-bacterium fermented opuntia ficus-indica fermentation extract in cosmetics, and belongs to the technical field of cosmetics. The invention provides a preparation method of a double-bacterium fermented opuntia ficus-indica fermentation extract and application of the double-bacterium fermented opuntia ficus-indica fermentation extract to cosmetics, and the preparation method roughly comprises the following steps: preparing opuntia ficus-indica stem slurry and rice milk, mixing the slurry and the rice milk, performing double-bacterium fermentation, centrifuging, retaining residues, and finally enriching supernate. According to the invention, food-grade opuntia ficus stem and rice are used for fermentation, and aspergillus oryzae and saccharomycetes are used for combined fermentation, so that the introduction of exogenous enzyme is avoided, macromolecular substances are fully decomposed through synergistic metabolism, the release rate of micromolecular active ingredients is increased, and finally, the effects of moisturizing, oxidation resistance, wrinkle resistance and the like of the product are further improved through enrichment.

The invention provides a recombinant microorganism with high yield of leucine as well as a construction method and application of the recombinant microorganism, two key exogenous enzymes, namely acetohydroxy acid synthase which is not subjected to feedback inhibition of leucine and an NADH-dependent acetohydroxy acid isoreductase mutant, are introduced to relieve the feedback inhibition effect of the leucine and improve the H balance of coenzyme NAD (P); therefore, the yield of the escherichia coli leucine is improved.

The invention relates to a saccharomycetes strain with high yield of esterifying enzyme and application thereof, the classification name of the saccharomycetes strain is Wickerhamomyces anomalus, the saccharomycetes strain is preserved in China General Microbiological Culture Collection Center on March 21, 2025, the preservation number is CGMCC 33925, and the address of the preservation unit is No.3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The strain screened by the invention has the ability of high yield of esterifying enzyme, and can synchronously catalyze synthesis of a plurality of key esters such as ethyl acetate, ethyl hexanoate, ethyl lactate and the like. Through the synergistic effect of polyesters, the flavor level of the liquor body is richer, and the liquor body is close to the composite aroma characteristic of the traditional solid fen-flavor liquor. The strain is naturally adapted to brewing of fen-flavor liquor and intensified application of medium and low temperature yeast, exogenous enzyme dependence is reduced, and the esterification capacity of yeast is improved.

The application discloses a method for preparing lactic acid by using a combined strain, and belongs to the technical field of microbial fermentation. Bacillus subtilis The combined strain comprises Bacillus subtilis Lactiplantibacillus pentosus LB9.The method for preparing lactic acid comprises the following steps: (1) preparing raw materials and strains, wherein the raw materials are white spirit lees; (2) mixing Bacillus subtilis and Lactobacillus pentosus after being activated respectively to form a combined strain, inoculating the combined strain into a culture medium taking the white spirit lees as the only fermentation substrate and without adding exogenous enzyme preparations and exogenous auxiliary materials, and performing fermentation; in the fermentation process, a staged oxygen supply strategy is adopted, namely, performing aerobic fermentation first and then performing anaerobic fermentation; and (3) collecting lactic acid from a fermentation product.The application realizes high-value utilization of lignocellulose waste, effectively coordinates metabolic conflicts among strains, and solves the problem of efficient conversion of lignocellulose lees into lactic acid.

A multi-part processed human amniotic composition configured to treat Peyronie's disease in a subject in need thereof by intracorporeal injection of the composition into the corpus cavernosum of the subject to reduce plaque size associated with Peyronie's disease. The multi-part processed human amniotic composition includes a micronized human amnion composition; and an aqueous human amniotic fluid filtrate configured to reconstitute and suspend the micronized human amnion composition therein. In certain aspects, the multi-part processed human amniotic compositions are not processed with exogenous enzymes during production thereof and do not include exogenous enzymes, such as collagenase, added thereto.

The application discloses a high-activity UGT1A1 enzyme based on tree shrew and a feed composition for enhancing alcohol metabolism. The catalytic efficiency of the recombinant tree shrew UGT1A1 enzyme on ethanol is significantly higher than that of human isozyme. The core of the application is to provide a complex feed system containing the enzyme, which solves the key bottleneck of poor stability and low delivery efficiency of exogenous enzymes in application through the synergistic effect of enzyme stabilizers, cell penetration enhancers, enteric coatings and coenzyme supply agents. Animal experiments show that the composition can safely and effectively accelerate in vivo alcohol elimination and reduce blood ethanol concentration, and can be used for developing alcoholism products, acute alcoholism treatment drugs and alcoholic liver disease prevention preparations.

The utility model relates to the field of oolong tea rocking barrels, and discloses an oolong tea adding external source enzymolysis rocking barrel which comprises a barrel body, a gear ring is arranged on the outer wall of the right end of the barrel body, the left side and the right side of the barrel body are both rotationally connected with fixing discs, a motor is installed on the right side of the fixing disc on the right side, and the driving end of the motor is fixedly connected with a rotating rod. A stirring rod is arranged in the barrel body, connecting buckles are arranged on the left side of a rotating rod and the right side of the stirring rod, a first belt wheel is arranged on the outer wall of the rotating rod, a fixing frame is fixedly connected to the front side of a fixing disc on the right side, a connecting rod is rotatably connected to the interior of the fixing frame, and a gear is fixedly connected to the left side of the connecting rod; the right side of the connecting rod is fixedly connected with a second belt wheel. According to the oolong tea enzymolysis device disclosed by the utility model, the motor, the belt pulley I, the gear, the gear ring and the stirring rod are matched with one another, so that the box body and the stirring rod rotate in opposite directions, and oolong tea is subjected to more comprehensive enzymolysis, so that the working efficiency is improved.

The invention relates to a method for improving the quality of oolong tea by using an exogenous enzyme, and belongs to the technical field of deep processing of tea leaves. The method comprises the following steps: mixing an exogenous enzyme solution with oolong tea leaves, adjusting the pH value, sealing, carrying out constant-temperature and constant-humidity treatment, and drying, the exogenous enzyme is one or more of tannase, protease and cellulase; the mass ratio of the oolong tea leaves to the exogenous enzyme solution is (20: 1)-(5: 2); the temperature of the constant temperature and humidity treatment is 45-55 DEG C, and the humidity of the constant temperature and humidity treatment is 75-90%. According to the method, the oolong tea leaves are treated by using exogenous enzyme, so that ester type catechin with relatively heavy bitter taste can be reduced by 4%, non-ester type catechin can be reduced by 9%, the content of soluble sugar is increased by 0.7%, the content of total amino acid is increased by 0.06%, and the quality of the oolong tea is improved; the method is green and environment-friendly, the treatment cost is low, and the shape of the tea leaves is kept.

This invention discloses a method for improving the flavor of sweet rice wine through low-temperature fermentation and its brewing technique, relating to the field of winemaking technology. First, a short-term temperature increase (28-30℃) is implemented in the early stages of fermentation to create an optimal environment for efficient saccharification and flavor precursor accumulation in Rhizopus. Subsequently, a low-temperature stage (15-20℃) is initiated, under which slow primary fermentation and flavor maturation, primarily driven by yeast, take place. The "staged temperature-increase saccharification + low-temperature fermentation" process provided by this invention does not rely on psychrophilic strains or exogenous enzyme additives; it can be achieved through optimization of process parameters. This method not only successfully solves the core problem of insufficient saccharification kinetics at low temperatures, ensuring the smooth progress of the fermentation process, but also significantly improves the sensory quality of the final sweet rice wine (more complex and harmonious flavor), as well as the content of umami and sweet amino acids. Furthermore, this process is highly controllable and suitable for large-scale production, providing a novel technological path for the green and efficient brewing of high-quality sweet rice wine.

Provided in the present disclosure are a yeast protein having an antibacterial function and a preparation method therefor. The method includes: S1, performing liquid fermentation on a Saccharomyces cerevisiae strain, and then performing separation to obtain a yeast milk; S2, acidifying the yeast milk to obtain an acidified yeast milk; and optionally performing autolysis, or exogenous enzyme catalytic hydrolysis, or mechanical crushing on the yeast milk to obtain a cell wall emulsion; S3, mixing the acidified yeast milk and the optional cell wall emulsion and performing autolysis to obtain an autolysis mixed solution; S4, performing first enzymolysis with compound protease; S5, performing second enzymolysis with seminase; and performing third enzymolysis with β-glucanase and cellulase to obtain a yeast protein emulsion; and S6, evaporating and concentrating the yeast protein emulsion to obtain the yeast protein. According to the method, a yeast protein having a broad-spectrum antibacterial function can be prepared.

The invention discloses an enzyme-activated fluorescent molecular precursor as well as a preparation method and application thereof. The enzyme-activated fluorescent molecular precursor has a chemical structure as shown in a formula I which is described in the specification. The invention develops an enzyme-activated fluorescent molecular precursor which can be used for real-time imaging of tumors by targeting exogenous enzyme to the tumors and specifically activating a probe at the tumors; according to the invention, the exogenous enzyme is introduced as an activation trigger, and normal cells do not have the exogenous enzyme, so that the problem of co-expression of the endogenous enzyme in non-tumor tissues can be avoided, background fluorescence signals can be reduced to the greatest extent, and the imaging specificity and accuracy are remarkably improved.

The present disclosure concerns a process for fermenting a biomass with a reduced dose of a purified exogenous enzyme (which can be, for example a purified exogenous glucoamylase). The process comprises contacting a biomass (which may comprise starch) with a recombinant yeast host cell. The recombinant yeast host cell has a genetic modification for expressing a heterologous polypeptide having starch or dextrin hydrolase activity (which may be, for example, from a glucoamylase). The nucleic acid molecule encoding the heterologous polypeptide having starch or dextrin hydrolase activity comprises allowing the secretion of the heterologous polypeptide.

The present invention is directed to a yeast strain, or strains, secreting a full suite, or any subset of that full suite, of enzymes to hydrolyze corn starch, corn fiber, lignocellulose, (including enzymes that hydrolyze linkages in cellulose, hemicellulose, and between lignin and carbohydrates) and to utilize pentose sugars (xylose and arabinose). The invention is also directed to the set of proteins that are well expressed in yeast for each category of enzymatic activity. The resulting strain, or strains can be used to hydrolyze starch and cellulose simultaneously. The resulting strain, or strains can be also metabolically engineered to produce less glycerol and uptake acetate. The resulting strain, or strains can also be used to produce ethanol from granular starch without liquefaction. The resulting strain, or strains, can be further used to reduce the amount of external enzyme needed to hydrolyze a biomass feedstock during an Simultaneous Saccharification and Fermentation (SSF) process, or to increase the yield of ethanol during SSF at current saccharolytic enzyme loadings. In addition, multiple enzymes of the present invention can be co-expressed in cells of the invention to provide synergistic digestive action on biomass feedstock. In some aspects, host cells expressing different heterologous saccharolytic enzymes can also be co-cultured together and used to produce ethanol from biomass feedstock.

The invention provides non-sugar-tolerant beta-glucosidase, an expression vector and application of the non-sugar-tolerant beta-glucosidase in improvement of cellulose degradation capacity, and belongs to the technical field of genetic engineering. According to the invention, the non-sugar tolerance type beta-glucosidase BGLC27 is obtained from streptomyces decomposer C27, and the amino acid sequence of the BGLC27 is as shown in SEQ ID No. 1. According to the invention, the BGLC27 is used as an exogenous enzyme and is added into a degradation system of cellulose degradation bacteria, and research finds that after the BLGC27 is exogenously added into the compound bacteria system, the cellulose degradation capability can be obviously improved.

The present application relates to the field of food technology, and discloses a low-bitterness wolfberry original syrup and a preparation process thereof. The original syrup is prepared from the following raw materials in parts by weight: 80-90 parts of fresh wolfberry fruit, 5-10 parts of germinated fava, 5-10 parts of germinated barley, 0.3-0.6 parts of medium-chain triglyceride, 1.0-2.0 parts of concentrated red date juice, 0.05-0.1 parts of ascorbic acid, 0.02-0.05 parts of citric acid, and 0.01-0.05 parts of saltwort extract. The present application efficiently reduces the bitterness of the wolfberry original syrup through a full natural biological transformation pathway without adding exogenous enzyme preparations or introducing chemical adsorbents, fundamentally avoiding chemical addition and clean label problems, and simultaneously achieving the synchronous transformation of various types of bitter substances in wolfberry. The preparation process of the present application completely retains the heat-sensitive functional factors and fresh fruit aroma of wolfberry, and the nutritional integrity and flavor reduction degree of the product are significantly better than those of similar products on the market.

The invention discloses a multifunctional active peptide from mackerel viscera and application of the multifunctional active peptide. The mackerel viscera extract is prepared by adopting a single exogenous enzyme hydrolysis method, the extract has small molecule peptides with ACE inhibitory activity, three ACE inhibitory peptides are obtained by further identification and screening, the amino acid sequences are respectively GPPVPGP, GPMGPMGP and SPGPVGMP, and the half inhibitory concentration IC50 values of the ACE inhibitory peptides are respectively 80.84 + / -1.12 mu g / mL, 177.41 + / -3.26 mu g / mL and 163.25 + / -3.46 mu g / mL. Wherein the heptapeptide GPPVPGP with the optimal activity also has the function of removing DPPH free radicals and hydroxyl free radicals, and can be used for adjuvant therapy for reducing hypertension or applied to other fields.

The invention discloses a black tea processing method for directionally releasing sweet flower fragrance characteristic components based on exogenous enzyme targeted regulation and control of glucoside hydrolysis. The black tea processing method comprises the following steps: withering fresh leaves, performing enzymatic treatment, performing gradient rolling, performing temperature-controlled humidity-controlled fermentation, and performing gross fire-spreading airing-complete fire staged drying on the fermented tea leaves, an enzyme solution sprayed for enzymatic treatment comprises one or more of an alpha-galactosidase solution with the activity being 0.5 to 0.6 U / mL, a beta-glucosidase solution with the activity being 0.6 to 0.7 U / mL, a cellulase solution with the activity being 200 to 210 U / mL and a papain solution with the activity being 1600 to 1700 U / mL; the sweet flower fragrance characteristic components comprise at least one of beta-myrcene, junifolene, citral, linalool, methyl salicylate, geraniol and nerol. The method solves the industrial problems of insufficient release of sweet flower fragrance characteristics, poor process stability and high dependence degree of raw materials in traditional black tea processing.

The invention discloses a cell-free protein expression system which comprises nucleic acid for coding target protein, a cell extract and a supplement system, and the supplement system comprises a nucleotide mixture, an amino acid mixture, a buffer solution, magnesium salt, potassium salt, L-glutamate and oxalate. Wherein the expression system contains an exogenous enzyme for converting L-glutamic acid into alpha-ketoglutaric acid. The invention also discloses a kit for cell-free protein expression and a method for expressing a target protein.

The invention provides a biosynthesis method for efficiently producing aromatic non-natural amino acid and site-specific modified recombinant protein, an engineering strain and application of the engineering strain. Specifically, the invention provides an engineering bacterium, and genes of one or more exogenous enzymes selected from the following groups are introduced into the engineering bacterium: threonine aldolase, threonine deaminase and transaminase; and threonine aldolase, threonine deaminase and transaminase are simultaneously expressed in the engineering bacterium. The engineering bacterium disclosed by the invention can be used for efficiently synthesizing aromatic non-natural amino acid through whole-cell catalysis or fermentation conversion. More importantly, the synthetic route provided by the invention can be synergistically coupled with a gene codon extension technology in the same engineering bacterium, and is used for high-efficiency expression of recombinant target protein modified by aromatic non-natural amino acid at a fixed point.

The invention discloses a method for increasing the content of sulforaphane in broccoli through magnetic field assisted blanching, and belongs to the technical field of food processing. The method for improving the content of sulforaphane in broccoli through magnetic field assisted blanching comprises the following steps: (1) preparing raw materials; (2) magnetic field assisted blanching pretreatment; (3) cooling and structure keeping treatment; (4) carrying out enzymatic incubation based on a magnetic field-assisted blanching regulation state; and (5) obtaining the broccoli product with high sulforaphane content. Exogenous enzymes, chemical reagents or additives are not introduced in the process, and the activity of endogenous myrosinase and the catalytic hydrolysis path of the endogenous myrosinase are regulated by synchronously applying a physical regulation means in the blanching pretreatment process, so that the generation level of sulforaphane in a treated sample is improved. The method is suitable for a food processing system, has the advantages of mild process conditions, strong controllability, high safety and easiness in industrial amplification, and has a wide application prospect in the field of food processing.

The invention discloses a method for degrading vomitoxin in coconut meal through microbial fermentation, and belongs to the technical field of coconut meal fermentation. In order to solve the problems of limitation of microbial strain screening culture, insufficient vomitoxin degradation efficiency and inaccurate fermentation process control, by screening and domesticating microbial strains, the specific enzyme activity is remarkably improved, efficient degradation of vomitoxin is realized, an environment suitable for microbial growth and metabolism is provided, and the vomitoxin degradation efficiency is improved. By combining the synergistic effect of microbial fermentation and an exogenous enzyme preparation, the vomitoxin degradation efficiency is improved to the greatest extent, the limitation of single microbial metabolism is broken through, particularly, remarkable advantages are shown in a high-mycin-polluted complex matrix, the vomitoxin content is remarkably reduced, and the vomitoxin degradation efficiency is improved to the greatest extent. The substrate quality of the coconut meal is maintained, and the efficient, safe and controllable vomitoxin degradation method is constructed through optimization treatment of the coconut meal substrate, microbial screening and domestication and the synergistic effect of exogenous enzymes.

The invention discloses a method for fermenting cigar core tobacco leaves by adding an exogenous enzyme preparation. The method comprises the following steps: uniformly spraying distilled water to the tobacco leaves for moisture regaining; placing the dampened tobacco leaves in a constant-temperature and constant-humidity box, and balancing moisture for 24 hours under the conditions that the temperature is 25 DEG C and the humidity is 80% until the moisture content of the tobacco leaves is 22%; diluting the exogenous enzyme preparation to a required concentration by using distilled water to prepare an exogenous enzyme solution; uniformly spraying an exogenous enzyme preparation solution on the surfaces of the tobacco leaves subjected to moisture balancing, and balancing moisture for 24 hours in a constant-temperature and constant-humidity box under the conditions that the moisture regaining moisture content of the tobacco leaves is 26%, the temperature is 25 DEG C and the humidity is 80%; and putting the tobacco leaves subjected to moisture balance into a constant-temperature and constant-humidity box under the conditions that the temperature is 42 DEG C and the humidity is 80%, and fermenting for 7 days. According to the fermented tobacco leaves treated by the exogenous enzyme preparation, the quality characteristics of the tobacco leaves are improved, the aroma is richer, the aroma amount is increased, the aroma permeability is better, and offensive odor and irritation are reduced; the method plays an important role in improving the industrial availability of cigar core tobacco leaves.

The invention belongs to the field of agriculture, and particularly discloses a biostimulant compound fertilizer containing sea cucumber peptide and a preparation method thereof, the biostimulant compound fertilizer containing sea cucumber peptide comprises the following components by weight: 5-15 parts of a sea cucumber peptide compound metabolite, 10-20 parts of humic acid, 10-15 parts of potassium fulvate, 40-60 parts of a nitrogen-phosphorus-potassium compound fertilizer, 1-5 parts of trace elements, 5-10 parts of alginic acid, and 5-10 parts of chitosan, the sea cucumber peptide composite metabolite is prepared through microbial fermentation and comprises antibacterial peptide, polyglutamic acid and oligosaccharide. The sea cucumber peptide composite metabolite rich in antibacterial peptide-polyglutamic acid-oligosaccharide is efficiently prepared through a three-stage synergistic enzymolysis process and a microbial symbiotic fermentation technology, a functional synergistic system is formed by combining components such as humic acid and chitosan, the enzymolysis efficiency is remarkably improved, an exogenous enzyme is replaced with a viscera natural enzyme source, the production cost is reduced, and the method is suitable for industrial production. And the enzymolysis efficiency is improved by combining a body wall pretreatment technology.

This invention discloses a fully solid-state fermentation process for Astragalus membranaceus vinegar, specifically relating to the field of solid-state vinegar brewing technology. The process uses sorghum, rice husks, rice bran, wheat bran, Astragalus membranaceus, and Daqu (a type of starter culture) as raw materials, without adding any exogenous enzymes or chemical products. The process includes the following steps: S1. Astragalus membranaceus slices are diagonally sliced ​​and drained to a moisture content of 18%-22%; S2. Sorghum is steamed at normal pressure, with Astragalus membranaceus slices added after 20-25 minutes of steaming, and steaming continues for a total time of 40-60 minutes; S3. Sorghum undergoes variable-temperature alcoholic fermentation with rice bran, first-grain rice husks, and a portion of Daqu, without Astragalus membranaceus slices participating in this stage; S4. The mash is mixed with the remaining Daqu, wheat bran, second-grain rice husks, and softened Astragalus membranaceus slices under moist heat, and the moisture content is adjusted to 60%-65% before acetic acid fermentation, with the main fermentation temperature at 39℃-41℃; S5. The mash is aged in a sealed container with intermittent aeration; S6. Vinegar is obtained by gradient temperature leaching. This invention achieves simultaneous fermentation and self-degradation of Astragalus membranaceus fiber and in-situ conversion of its functional components through process timing control and physical parameter optimization.

The invention discloses a processing method for improving clarity of instant tea, and belongs to the technical field of deep processing of tea leaves, the method mainly comprises the following steps: extracting and roughly filtering tea leaves to obtain primary tea soup; adding a compound enzyme into the primary tea soup, carrying out enzymolysis treatment, and then carrying out enzyme deactivation; sequentially performing ceramic membrane microfiltration, ultrafiltration membrane fine filtration and nanofiltration membrane concentration on the treated tea soup; quickly cooling the obtained concentrated solution, standing and aging at low temperature, and centrifuging at high speed to obtain supernatant liquid; and finally, drying to obtain the instant tea powder. According to the method, various substances causing turbidity in tea soup are systematically removed through the synergistic effect of exogenous enzymolysis, three-stage membrane integrated purification and low-temperature physical coagulation acceleration, and the method has the beneficial effects that the final clarity and cold water solubility of an instant tea product can be effectively improved, and the storage stability of the product is improved.

The application provides a vinegar residue-based single-cell protein feed and a preparation method and application thereof, and belongs to the technical field of feed preparation.The application uses vinegar residue as raw material, adopts solid-state fermentation of Aspergillus, Candida utilis and Saccharomyces cerevisiae in combination with composite enzymes, utilizes the synergistic effect among the strains and the enzymolysis effect of the exogenous enzymes, efficiently degrades the fibrous substances in the vinegar residue, and converts the fibrous substances into microbial proteins, so that the crude protein content of the prepared vinegar residue-based single-cell protein feed is increased from 5% to 8% of the raw material to 20% to 25%, and the total fibrous substance degradation rate is greater than or equal to 60%. The vinegar residue-based single-cell protein feed produced by the application has good feeding value, can effectively replace part of the protein raw materials such as soybean meal, improves the production performance of beef cattle, reduces the breeding cost, realizes high-value utilization of vinegar residue resources, and has good popularization and application prospect.

The present invention relates to the field of genetic engineering technology, and discloses a plasmid-free genetically engineered bacterium with high yield of L-2-amino butyric acid and its application. The plasmid-free genetically engineered bacterium for producing L-2-amino butyric acid provided by the present invention is obtained by modifying Escherichia coli THR as a chassis cell through metabolic engineering and gene editing technology. This genetically engineered bacterium strain can use glucose as a raw material and obtain L-2-amino butyric acid through fermentation culture. Without adding exogenous enzyme activity by plasmids, the batch-fed fermentation yield in a 5L fermenter reaches 13.81 g / L. It has low fermentation cost, high product concentration, no by-products affecting, and the product is easy to purify, and is suitable for industrial applications.

Provided in the present invention are a biosynthesis method for efficiently producing aromatic unnatural amino acids and site-specifically modified recombinant proteins, an engineered strain, and use thereof. Specifically, the present invention provides an engineered bacterium. Genes of exogenous enzymes, threonine aldolase and threonine deaminase, are introduced into the engineered bacterium, and the engineered bacterium expresses both the threonine aldolase and the threonine deaminase. The engineered bacterium of the present invention enables efficient synthesis of aromatic unnatural amino acids by means of whole-cell catalysis or fermentation transformation. The synthetic route of the present invention can be synergistically coupled with gene codon extension technology in the same engineered bacterium for efficient expression of recombinant target proteins site-specifically modified with aromatic unnatural amino acids.

A subject-matter of the present invention is a method for the dyeing of keratin fibres employing a composition C comprising: (i) indican of formula (I) and / or a powder containing it; (ii) at least one exogenous enzyme of hydrolase type; (iii) at least one exogenous enzyme of oxidase type; and (iv) water.