Study On Improving Efficiency Of Bacteria For Biological Nitrogen Removal By Cell Fusion

Nitrogen pollution in nature water becomes increasingly serious, the development of new denitrify process attracted great attention of the sewage disposal researchers. In recent years, more people have begun to use molecular biology and genetic engineering techniques to transform characteristics of microorganisms and to obtain high degradation activity, then can improve the effectiveness of biological and chemical treatment plant.Conventional biological nitrogen removal process includes the process of ammoniation, nitrification and denitrification. Ammonifiers, nitrobacteria and denitrifying bacteria play a determinative role in these three processes. Isolating and screening those bacteria and applying them in wastewater treatment can be a basis for the developing of new technology of nitrogen removal process. To construct engineering bacteria through protoplasts fusion can breed superior strain. The application of protoplasts fusion in wastewater treatment has been reported a lot yet. This paper have purified and isolated three strains of ammonifiers, nitrobacteria and denitrifying bacteria separately. The nitrogen removal rate of strains y3,x3 and f1 are higher than the other strains. Y3 is nitrosococcus, x3 is nitrococcus, and f1 is denitrifying bacillo. Used y1, y3; x1, x2; and f1, f3 as parent strains separately cultivated fusant y13, f12. Y13 and f12 can be identified as nitrococcus and denitrifying bacillo. Strain y13 improved the nitrogen removal rate by 15.9 percent compared with strain y1, and strain f13 improved the nitrogen removal rate by 43.4% percent compared with strain f3. Those result can proved that protoplasts fusion can breed superior strain than parent strain.