Research On Mutatation Breeding Of Falvomycin Producing Strain By Low Energy Ion Beam

Over the past decade, the feed additives receive a rapid application in the world, and the issues arising are not only the competition among enterprises producing the same species, but also that among those of different varieties and similar functions. This requires the enterprises constantly innovating and continuously improving the quality of the product in order to remain invincible position. Therefore, it is of great importance to utilize the new method of orienting genetic improvement with China's independent intellectual property rights and being recognized by the international—"Ion Beam Breeding Technology", which can breed Flavomycin bacteria with high quality and good viable ability, create new germplasm of micro-organisms, and improve competitiveness of the enterprises .Taking the Flavomycin bacteria 08-126F₂ as test object, the thesis uses the technology of low-energy nitrogen ion beam mutating microbe and conducts the mutagenic experiment aiming at increasing the metabolism production microbial and activity, which obtains the mutant 08N⁺-28F₁ with higher shake-flask titers and makes a preliminary optimization of its medium.First of all, we studied the mutagenic effect of the original strain through the low-energy nitrogen ion beam, and then studied the mutating rate and survival rate of different doses of nitrogen ion injecting Flavomycin strains. Thus, the best injection parameter was determined: energy: 10kev, dose: 150×2.6×10¹³ ions(cm²Â·s)^-1. The variable rate of Flavomycin bacteria is 35% under this implantation dose. Comparing with the original strain, we have got a shake-flask titers of 2.5 times strain 08N⁺-28F₁, and ascertained the best training period is 20h.Secondly, we made a three level orthogonal test of the four kinds of important raw materials in the fermentation shake flask formulation for the high-yielding Flavomycin producing strain bred by low energy ion beam. The result showed that the best recipe was corn steep liquor 1.0g/100ml, soybean meal 3.2g/100ml, corn starch 3.0g/100ml, (NH₄)₂SO₄ 0.4g/100ml. This article also reviewed the influence of different concentrations glucose on the yield of Flavomycin and found that different concentrations glucose exerted different effects. Among them, 0.6g/100ml had more visible role in promoting.Finally, the author discussed the mutagenic effects mechanism of the low energy ion beam on Flavomycin producing strains and the three "protective enzymes" of Flavomycin producing strains. The conclusion was that the three "protective enzymes" of the high-yielding strains had obvious improving.