Mutation Breeding Of Productive Strain Of γ-Poly(glutamic Acid) And Applied Study On Absorption Of Cu～(2+) By γ-Poly Glutamic Acid

γ-Poly (glutamic acid) (γ-PGA) is a water-soluble and biodegradable polyamino acid with a high relative molecular mass, and it was produced by microbiology outside of the cells. And it is water soluble, biodegradable, edible, and non-toxic toward humens and the environment. Therefore, potential applications of γ-PGA and its derivatives have been of interes in the past few years in a broad range of industrial fields such as food, cosmetics or medicine and water treatment. So it is a novel bioproductions that is worth to exploitation and using.Because γ-PGA has an extensive potential value to exploitation and apply in the society, this article adopted a novel idea of more effective mutation breeding to treat Bacillus licheniformis ATCC 9945A, which can produce Y -PGA effectively, which is totally different from the traditional way. And in the novel idea, we can obtain mutant strain with good characters effectively.Otherwise, we also have studied a special sorbent is made in laboratory by biodegradable γ-Poly(glutamic acid), γ-PGA was combined with the carrier—Glutaraldehyde in the crosslinking reaction and then used in heavy metal absorption. The result showed γ-PGA was of great absorbability to heavy metals.The main content include:Ⅰ.Mutation breeding by mixing several groups of mutant strains for fermentation to treat Bacillus licheniformis ATCC 9945A, so the mutantstrain can produce a lot of γ -PGA.Ⅱ. Proceed the re-mutation breeding of the mixture of the 5 most productive strains from step I to promote the produce of γ-PGA further. At the same time choose out the most productive strain and determine its growth curve and time cours of γ-PGA flask fermentation. Ⅲ.Research on the Cu2+-adsorption ability of Y-PGA. The main results are showed below:Ⅰ. In this research we lay out for the first time the technique of mutation breeding by mixing several group of mutant strains and fermentation. Base on that idea I have designed several mutation conditions to treat Bacillus licheniformis ATCC 9945A, which can produce γ-PGA, and mixed all the mutant strains after treatment. As fermenting this unscreened mixture of mutant strains, and optimizing the fermentative process according to the yield of γ-PGA, the condition tend to fit for the positive strain, and the yield of γ -PGA increased. On the mix-strains situation, meanwhile, the best fermentative process for the positive strain which has the higher yield of γ-PGA was found, and then it was used as the screen plate to separate and purify the mix-strains. In this way a strain Z γ-29 had been quickly and effectively bred from only 40 individual strains, of which the yield has increased 4. 15 times than the 4. 582g/L of original strain. And the optimized fermentative process for that strain has also been found out. The result showed that this is a novel idea to obtain mutant strain with good characters effectively, which may lay forth a new way for other microbe' s mutation breeding work.Ⅱ. I have obtained a more productive strain Bacillus licheniformis Z γ —50, of which the yield of γ-PGA got another promotion by 23. 6%. Andmy research work was successful in this step, which indicated the advantage and feasibility my idea of mutation breeding by mixing several group of mutant strains and fermentation. On the other hand, I have determined the Time couse of Bacillus licheniformis Z γ-50 in γ -PGA flask fermentation, Which showed that the synthesis of y -PGA is correlative with the growth of the bacterium, but direct proportion was absent between the amount of bacterium and the concentration of γ -PGA synthesized.This result indicated that γ —PGA may be a sub-metabloicproduce, which can only be synthesized in large quantity when the Bacillus licheniformis reaches its stable phase.Ⅲ. I' ve studied the application of γ-PGA on Heavy Metal Sorption. Link y-PGA to the carrier, and use the UV-spectrophotometer to investigate its Cu2+-adsorption ability according to the standard curve determined previously. I have studied the process of the manufacture of adsorber and the element effecting the adsorption, which include the moment when Y -PGA is added, the temperature and time of linking and adsorption, and original concentration of Cu2+. The result of the research shows that when use Glutaraldehyde as the linker, reacting at 20℃ for 2h, γ -PGA can stably link to carrier. And when I added γ -PGA to the solution for making the membrane, the effect is much better than merely add y-PGA when linking is proceeded. And my research also confirms that γ-PGA has the ability of Cu2+-adsorption, and when different form of adsorber is choosed, the efficiency is different, too. My research shows that the γ-PGA -linked carrier is more efficient in Cu2+-adsorption than none-linked one.