| Poly-gamma glutamic acid is a new type of biological macromolecule material, it is made up of glutamic acid monomer which is connected by alpha amino and gamma carboxyl,it has excellent water absorption performance, its maximum water absorption ratio can reach1:3500, this nature has wide range of applications In additionin of the cosmetics,pharmaceutical excipients, penetration and other fields. The gamma poly glutamic acid also has good biocompatibility, ductility, plasticity and other characteristics, Which has development and application potential. But now its strains still have lower production rate and high production cost, and all of this limit its application in various fields and development.This experiment aims to establish a sensitive, simple gamma poly glutamic acid content detection method, mutation breeding a high yield strains of gamma- poly glutamic acid strains, and through optimizing the culture medium and culture conditions, to achieve the purpose of reduce the production cost.Based on the cetyl trimethyl ammonium bromide and poly gamma acid can form the theoretical basis of complex compound in alkaline conditions, to investigating its complexation time, concentration of complexing and the concentration of sodium hydroxide,ultimately determine the turbidimetric method to detect gamma- the best conditions for poly glutamic acid concentration: the hexadecyl trimethyl ammonium bromide concentration of 6g/L, the sodium hydroxide concentration is 4%, the optimal complexing time is 3 min, the detection wavelength is 250 nm. On this condition, make the establishment of standard curve,the equation for it is: y = 0.03245 x- 0.12367, theR2 is 0.9977, and it is with good reproducibility.Using soybean meal as basic medium, change the type of carbon source, carbon nitrogen ratio, amino acid and amino acid, inorganic salt ion salt, inoculation quantity, PH value and other factors in single factor experiment, the screen has obvious effects of gamma- poly glutamic acid production of the four factors respectively, amino acids and amino acids,inorganic salt ion salt, PH value and quantity. By four factors and three levels orthogonal experiment, fanily reslut is :the optimal combination of glutamic acid is 6%, inorganic salt ion content is 0.2%, the PH value is 7.2, the inoculated quantity is 5%. Test this combination for validation, get a gamma- poly glutamic acid production is 62.40 mg/g, increased by32.18%.more than 47.21 mg/g before.Chemistry mutagenesis and composite mutagenesis induced means is carried out on laboratory preservation strains HG- 009 physical mutagenesis, to increase the production of gamma- poly glutamic acid. With ultraviolet 20 w, the conditions of 10 cm, mutagenesis 60 s,the gamma poly glutamic acid production by 61.31 mg/g up to 69.04 mg/g. Then through 15 min 2% of DES mutagenesis, gamma, poly glutamic acid production fuon 61.90 mg/g up to71.39 mg/g. After the 800 w microwave mutagenesis 25 s, make gamma poly glutamic acid production from 62.22 mg/g up to 71.88 mg/g. Finally based on the best condition of each single factor for compound mutagenesis, the gamma poly glutamic acid production from62.40 mg/g up to 72.87 mg/g. Overall, by mutagenic factors and medium optimization,gamma, poly glutamic acid in total increased by 54.35%.Using phenol- sulfuric acid method to determine the gamma- poly glutamic acid content of polysaccharide in yeast, it is concluded that the change of its content and the proportion trend, namely as the gamma- poly glutamic acid the breeding of high yield strain,polysaccharide content increased from 81.2 mg/g to 87.3 mg/g, which is a 7.5% increase. This change may be related to strain increases metabolism of mutation breeding in the process of growth, the study, for the gamma poly glutamic acid in removing impurity in the actual production, purification, offer reference for gamma- poly glutamic acid fermentation product composition and its content analysis provides a new train of thought. |
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