Study Of The Screening On The Escherichia Coli With The Ion Implantation And Preliminary Research Of Culture Conditions

Low-energy ion implantation has been considered as new kind of mutation breeding and foreign gene delivery techniques. By the means of implanting low-energy ions into organisms, the biological effects and the function mechanisms of the technique were investigated by some researchers. Although the researchers have observed some biological effects and reveals some basic mechanisms since past the decade, they do not master the roles of low-energy ion implantation, and the studies on the law of inheritance in the microorganism irradiated by low-energy metal ions has not been reported so far. In our experiments, choosing the Escherichia coli containing aspartate transminase as the target of low-energy ion implantation, we observed and counted the biological effects of the E.coli to make the fundaments for exploring the interaction between low-energy ions and complicated organisms further. At the same time by strain breeding high-yielding E.coli can we make an improvement the productivity of L-Phenylalanine. The experiments were divided into several parts: first of all, the best E.coli was screening from laboratory preserved bacterium after rejuvenating, culturing and determining the activity of the aspartate transminase. We chose the high-yielding strain as the beginning E.coli waiting for farther irradiated with low-energy ions. Then, we chiefly investigated the biological effects and function mechanism of the technique by the means of implanting low-energy N~+ ions into E.coli and studied the interaction between low-energy and E.coli by irradiating it with different energy, dose. Through protracted the curve of survival rate of irradiated with different energy and dose, we found out the optimum implanting energy and dose. And we obtained the mutation strains which were irradiated by implanting optimum-energy N+ time after time. In the shaking flask, the L-Phenylalanine productivity of mutation strains increased by 6% than of the original strain with the PPA concentration of 20g/L. Because the studies on the law of inheritance in the microbe irradiated by low-energy metal ions has not been reported so far, we explored the aspects by means of implanting metal ions such as Ti2+,Ag+,Fe2+,Zn2+ into E.coli On basis of experimental results, we primarily discussed characteristics, mutation mechanism and bio-effect on metal ion beam implantation. The theory on metal ion beam implantation need more experiments to confirm. In addition, we carried on optimizing culture condition of E.coli in the shaking flask and 5L fermentor. The important factors which affect culture and bioconversion conditions of E.coli were determined elementary. Through a series of experiments, we optimized the culture parameter, such as fermentation time,inoculation,temperature,agitation speed and so on. It was confirmed that the mutation strain was capable to produce L-phe of industrialization.