Study On Radiation Resistance Of Acidophilic Iron/Sulfur Oxidation Bacteria

Uranium bio-leaching system is of radioactive,in which iron/sulfur oxidized bacteria may be affected by radioactivity.But from all the literature reported now,it is difficult to combine eosinophilic bacteria and radiation resistance,to improve the activity of iron-sulfur-oxidizing bacteria in bio-leaching uranium system is very necessary to study the radiation resistance or tolerance of such bacteria.In this paper,we selected three Acidithiobacillus ferrooxidan strains which come from Jiangxi 719 uranium mine,Hebei Qinhuangdao 754 uranium ore and Xinjiang 737 uranium ore,and a Acidithiobacillus thiooxidans strain of Jiangxi 719 uranium mine.and research differences resistance between Acidithiobacillus ferrooxidan and Acidithiobacillus thiooxidans against UV irradiation and60 Co radiation.And observe the morphological changes of the60 Co irradiated strains by scanning electron microscopy and observe the effect of UV irradiation and60 Co irradiation on the DNA of different strains by fluorescence in situ hybridization.Finally observe the changes of the activity of catalase in different strains which can measuring the change of hydrogen peroxide concentration in the culture medium.Research indicates:Different strains have different radiation resistance.A.f and A.t can tolerate 62.1J /cm~2 dose of ultraviolet radiation,four strains all can tolerate 0.7KGy dose irradiation when60 Co irradiation dose rate is 175 Gy / h,F1L2BY14C-f can tolerate 2KGy dose irradiation when 60 Co dose rate is 307.7Gy / h,but low dose rate and low dose irradiation is easier to make A.f and A.t cell death than high dose rate and high dose irradiation.Same kind of strains which come from different places also have different radiation tolerance.The results showed UV irradiation resistance of three A.f strains which come from different places's rank as:C3MMYX-f(512Uranium Mine)>F1L2BY14C-f(719??)>E3mYX1C-f(754??);~60Co irradiation resistance rank as:F1L2BY14C-f(719??)>E3mYX1C-f(754??)>C3MMYX-f(512??).The difference between UVirradiation resistance and ~60Co irradiation resistance of F1-s is obvious,F1-s can tolerant high UV irradiation but low~60Co irradiation resistance.UV mutagenesis could increase the resistance of the strain of ~60Co?-ray.By UV mutagenesis of strain F1-f,we obtained a strain which can tolerance 2KGy dose of~60Co irradiation at a dose rate of 307.7Gy/h,and its bivalent Iron oxidation capacity is also higher than the original strain.It was observed by SEM that the cell morphology of A.f/A.t was changed by UV irradiation and 60 Co irradiation.The change caused by UV irradiation is small,60 Co irradiation can cause serious cell deformation.FISH test results show that 60 Co irradiation can cause direct changes in the DNA of the strain.UV irradiation could significantly decrease the activity of catalase in the cells.And UV irradiation time was negatively correlated with the activity of intracellular catalase,60 Co irradiation at 0.7KGy dose resulted in a significant increase in the activity of catalase in strain F1-f cells;The 60 Co irradiation below the cumulative dose of 2.1KGy had little effect on the activity of catalase in cells of DR;and 2.1KGy cumulative dose of60 Co irradiation will cause a slight increase in the activity of catalase in E.coli cells.