Background technology
(γ-PGA) is the outer polypeptide of a kind of born of the same parents that is produced by multiple bacillus to gamma-polyglutamic acid-, and it is the main ingredient of certain micro-organisms pod membrane, is a kind of water-soluble and biodegradable polymer substance.It is to be formed by connecting by the γ amido linkage by D-type or L-type L-glutamic acid.γ-PGA is found in nineteen thirty-seven the earliest, and the researchist has found γ-PGA in the cell pod membrane of Bacillus anthracis and in the cell pod membrane of amylomyces, and proves that it is one of main component of certain micro-organisms pod membrane.In subtilis and bacillus natto, also find γ-PGA afterwards.γ-PGA is a kind of peptide molecule that is formed with the form condensation of peptide bond with γ-carboxyl and alpha-amino group by D-L-glutamic acid (D-GLu) and L-L-glutamic acid (L-GLu) monomer.Have the higher side chain carboxyl group of a large amount of activity on the molecular chain of γ-PGA, have high moisture retention and water-absorbent (1: 3500, m/v).Be easy to some medicines in conjunction with generating stabilized complex, be the biodegradable pharmaceutical macromolecular material of a class ideal.γ-PGA environmentally safe is the green bio product.The nineties in 20th century, some developed countries such as Japan, the U.S. were very active to its preparation and the research of using, and carried out the research that utilizes liquid submerged fermentation to produce γ-PGA.The γ of Japan-PGA research and development are positioned at prostatitis, the world, and Ajincomoto Co., Inc has successfully developed the biological production technology of γ-PGA.At present, the method for extraction mainly contains: organic solvent precipitation method, chemical precipitation method or the membrane sepn precipitator method obtain γ-PGA.But the method that prior art is extracted exists production cost height, extraction process complicated technology problem.
Summary of the invention
The purpose of this invention is to provide the novel technology for extracting polyglutamic acid that a kind of technology is simple, production cost is low.
The present invention operates by following processing step:
(1) detects γ-PGA content, pH, soluble protein content in the fermented liquid;
(2) open stirring, slowly transfer fermented liquid pH to 3.0-5.0 with 1-15% dilute hydrochloric acid;
(3) carrying out thalline with the pump delivery fermented liquid to supercentrifuge separates, separating clear liquid goes in the enzymatic vessel, open the sodium hydroxide solution that stirs with 1-20% and transfer fermented liquid pH to 6.0-8.0, opening steam slowly heats up, the fermented liquid temperature is remained between 30 ℃-50 ℃,, add proteolytic enzyme in the ratio of 0.1%-10% according to soluble protein content in the fermented liquid, open and stir insulation 5-7 hour, make protein hydrolysis thorough;
(4) remove behind the albumen clear liquid once more high speed centrifugation remove insolubles, slowly transfer centrifugal stillness of night pH to 3.0-5.0 behind the enzymolysis with 1-15% dilute hydrochloric acid, dialyse concentrated to ultra-filtration membrane with pump delivery;
(5) through ultrafiltration and concentration, remove small molecular weight impurities such as pigment and salt, other amino acid, ultrafiltration and concentration liquid goes in extractor;
(6) open stirring and slowly transfer ultrafiltration and concentration liquid pH to 6.0-8.0 or 2.0-4.0 with the alkali lye of 1-20%, slowly stream adds the ethanol of 60-90 degree, makes fermented liquid form milky suspension liquid, has grey or xanchromatic glue slag to occur simultaneously;
(7) suspension liquid and glue slag go to whizzer with pump, and the centrifugal slag that removes photoresist that removes obtains pure emulsion;
(8) emulsion goes in the second extraction jar, opens an amount of solid salt of the slow adding of stirring and separates out colloid, separates out fully until colloid, stops stirring the sedimentation colloid 1-5 hour, shifts top ethanol;
(9) open stirring and repeatedly added an amount of 80-100 degree alcohol immersion colloid 1-3 hour, reduce colloid viscosity) go to whizzer with pump and carry out solid-liquid separation, the colloid after the separation carries out vacuum lyophilization or vacuum dehydrating at lower temperature, makes the gamma-polyglutamic acid-finished product.
Gamma-polyglutamic acid-novel technology for extracting of the present invention adopts multiple effective means to remove impurity in the fermented liquid, has promoted end product quality, has following outstanding advantage:
1, transfer fermented liquid pH to 3.0-5.0 to reduce fermentation broth viscosity with diluted acid, the high speed centrifugation fermented liquid is removed thalline, the simple efficient large-scale production that is fit to of technology;
2, centrifugal clear liquid adds protein hydrolysis and is further purified feed liquid;
3, the centrifugal clear liquid acid adjustment behind the enzymolysis is dialysed through ultrafiltration and concentration, removes small molecular weight impurities such as pigment, salt, other hydrolysis amino acid, has effectively saved steam, ethanol consumption simultaneously;
4, add salt and cooperate the extraction using alcohol colloid, compare with independent use ethanol to extract and saved the ethanol consumption;
5, lyophilize or vacuum dehydrating at lower temperature have guaranteed quality product;
Embodiment
With tank body volume 100L fermentor tank is example, adopts the present invention to extract γ-PGA technology, and step is as follows:
(1) detects fermentation sol content 4.6g/100ml, pH6.6 5, soluble protein content 0.54g/L, volume 50L;
(2) open stirring, slowly transfer fermented liquid pH to 3.0 with 10% dilute hydrochloric acid;
(3) carry out 13000r/min high-speed separation thalline with the pump delivery fermented liquid to supercentrifuge, separating clear liquid goes in the enzymatic vessel, open the sodium hydroxide lye that stirs with 10% and transfer fermented liquid pH to 6.6, opening steam slowly heats up, make the fermented liquid temperature remain on 40 ℃, add 1.4g proteolytic enzyme according to fermented liquid soluble protein content, open and stirred insulation effect 6 hours, make the enzyme effect thorough;
(4) carry out 13000r/min high-speed separation insolubles with pump delivery enzymatic hydrolysis and fermentation liquid to supercentrifuge, centrifugal clear liquid is slowly transferred pH to 3.0 with 1-15% dilute hydrochloric acid behind the enzymolysis, dialyses concentrated to ultra-filtration membrane with pump delivery;
(5) concentrate through ultrafiltration dialysis, remove wherein pigment and salt. small molecular weight impurities such as total free aminoacids, concentrate back material liquid volume 40L, ultrafiltration and concentration liquid goes in extractor;
(6) open stirring and slowly transfer ultrafiltration and concentration liquid pH6.0 with 10% sodium hydroxide lye, slowly stream adds the ethanol of 80 degree, and making fermented liquid form milky suspension liquid has the glue slag of grey or yellow-gray to occur simultaneously again;
(7) suspension liquid and glue slag go to whizzer with pump, and the centrifugal slag that removes photoresist that removes of 4000r/min obtains pure emulsion;
(8) emulsion goes in the second extraction jar, opens the slow solid food level salt that adds of stirring and separates out colloid, separates out fully until colloid, stops stirring the sedimentation colloid 1 hour, shifts top ethanol;
(9) open stirring and repeatedly added an amount of 95 degree alcohol immersion colloids 3 hours, go to whizzer 500r/min with pump and carry out solid-liquid separation, the colloid after the separation carries out lyophilize or vacuum-drying, makes 1.35Kg finished product γ-PGA.