Acid-tolerant Domestication Of Microorganisms Used In The Remediation Of Strong Acid Uranium Wastewater

In-situ leaching of uranium is the key core technology of my country’s natural uranium production,and its production capacity accounts for more than 90%of my country’s total production capacity of natural uranium.In the early production,some in-situ leaching uranium mines in my country used H₂SO₄as the leaching agent and HNO₃as the eluent and oxidant,which resulted in the low p H of groundwater and the excessive uranium and NO₃^-content.Therefore,it is urgent to carry out treatment.Compared with traditional physical and chemical methods,microbial remediation methods are more environmentally friendly to treat this type of wastewater.In order to further enhance the performance of microorganisms to remove NO₃^-in the groundwater of low-p H in-situ leaching uranium mines and the performance of hydrolyzing sodium phytate to remove uranium,this study used Acinetobacter jonii and Burkholderia sp as the test strains.The acid-tolerant gradient acclimation was carried out,and the growth characteristics of Acinetobacter jonii and Burkholderia sp.before and after acclimation and the changes in the performance of removing NO₃^-and hydrolyzing sodium phytate were studied.The results showed that:（1）During the gradient acclimation process from p H 7.0 to 3.0,the lag phase of Acinetobacter jonii and Burkholderia sp.gradually prolonged with the decrease of p H;the two strains were acclimated three times at the same p H value.After that,the growth rate during the second transfer and acclimatization was not significantly higher than that in the first transfer and acclimatization,and the growth rate during the third transfer and acclimatization was significantly higher than that in the first transfer and acclimatization.（2）At p H values of 5.0,4.0,and 3.0,the lag period of Acinetobacter jonii after acclimatization was shortened by more than 10 hours than before acclimatization.When the p H value is 3.0,the biomass of Acinetobacter jonii after domestication is 1.5 times higher than that before domestication,and the ability to remove NO₃^-is 3.9 times higher than that of the original strain.（3）After Burkholderia sp was acclimated with a gradient of p H 7.0 to 3.0,under the condition of p H 3.0,the biomass of Burkholderia sp after acclimation increased by 11.8 times compared with that before acclimation.In addition,with the decrease of p H value,the ability of the domesticated Burkholderia sp to hydrolyze sodium phytate is more and more different than that before domestication.Under the condition of p H 3.0,the ability of the domesticated Burkholderia sp to hydrolyze sodium phytate was9.73%,which was 47.6 times higher than that before domestication.（4）Under the condition of p H 3.0,the nas S gene expression of the domesticated Acinetobacter jonii was significantly higher than that before the domestication;the domesticated Burkholderia sp.under the condition of p H3.0,the phy C gene expression The expression level is significantly higher than before domestication.This study shows that the acid-tolerant gradient domestication of microorganisms can enhance the adaptability of microorganisms to low-p H environments,increase their biomass and biological activity in the groundwater of low-p H in-situ leaching uranium mines,thereby improving their restoration of low-p H soils.The performance of groundwater in leaching uranium mines.