Study On Preparation Conditions And Properties Of Poly - γ - Glutamic Acid And Its Copper Complexes

Poly-γ-glutamic acid is a Polymer material of amino acid homopolymer. Due to large number of amide bonds in molecule and intermolecular hydrogen bonds, the molecule has biodegradability and water retention performance, and is widely used in medicine, agriculture etc.But there is rarely study about coordination ability between glutamic acid and metal ion. Amino nitrogen and carboxylic hydroxyl oxygen, contained in Glutamic acid, can provide a lone pair of electrons for metal ion and are two atoms with strong coordination ability. So, they usually are exploited as centrosome of coordination. Hence, the molecules can complex with transition metals or rare earth, and form a stable new substances. Whether it’s transition metal or other rare earth elements, show certain sterilization ability, and now many antibacterial agents made of inorganic metal salts have been widely applied in real life. But these antibacterial agents tend to cause some residue and the destruction of the environment. At the same time, they also cause threat to human. Therefore, by studying the chelating properties of poly-γ- glutamic acid and metal ions in a certain concentration range, we can prepare an organic metal complex, which not only can be used in antibacterial but also as food additives or fertilizers. It may have great value of application in this way.Bacillus WBL-3 is a preserved strains in laboratory which can secrete extracellular production called poly-γ-glutamic acid. By optimizing medium, the strain can produce secreted extracellular sticky substance. The ninhydrin test, as well as UV-Vis scan experiment and HPLC separation experiments on the acid hydrolysate of the viscous substance reveal that the majority of the monomer substance is glutamic acid, and the content of glutamic acid is more than 80%, We can determine that the fermentation product is poly-γ-glutamic acid. With UV-Vis spectroscopy experiments scanning method, infrared spectroscopy scanning method, cold field emission scanning with electron microscopy techniques, we can analyze and identify the complex products. It’s found that the copper ions could ligand with the amino nitrogen and oxygen carboxy hydroxyl on the poly-γ-glutamic acid chain simultaneously, and even form a cyclic structure. I set temperature, mass ratio, pH, reaction time four factors inmy experimental to start my study on chelating rate between poly-γ- glutamic acidcopper, and analysis the four factors with orthogonal experiment. It’s found that under the single factor, the chelating rate reached maximum when conditions: temperature 70 ℃, mass ratio 3:2, pH4 ~ 5, the reaction time 50 min.The variance analysis of orthogonal experiment show that the optimal combination of four factors is: A2B4C3D2, and the mass ratio of 3:2, the temperature 75℃, pH 5, reaction time 50 min.Under these conditions, the rate of chelation can reach 85.64%.Study found on the complex antibacterial properties that, compared with inorganic salt of copper, the antibacterial properties of the new complexes decrease slightly, but still exist some antibacterial ability for each strain. The study reveals that the antibacterial activity of complex is stronger on bacteria than on mold. Through the analysis on the rate of germination of mold spores, the complex has strong lethality on mold spores, and could create certain limitation to the growth of hypha.