Isolation Of A Selenite-reducing Strain And Research On Its Characteristics Of Growth And Selenite-reduction

In this study, some strains of Selenium-tolerance microorganisms were obtained by the processes of enrichment, separation and depuration in the soil of high-Selenium from yutangba, enshi, hubei province. We screened a bacterium which can reduce sodium selenite and tolerate Sodium Nitrite up to60mmol/L. Through16s RNA sequencing, we identified this strain is Stenotrophomonas maltophilia which is a novel type in the sodium selenite reducing bacteria.From the researches about the strain growth, we found the growth was delayed when being treated with sodium selenite solution. In the life cycle of the strain, the pH value increased gradually from pH6.5to pH8.3in liquid medium. The strain’s generation time is177min in the2mmol/L LB liquid medium. In the Primary research about the sodium selenite reducing ability of the strain, it was found the reducing rate up to97.8%when culturing the bacteria to87h in the2mmol/L LB liquid medium.To modify the growth condition of the strain, it was determined the more appropriate temperature is25℃-35℃,the most suitable pH value is7, the proper bacterial loads are4%-8%and orthogonal tests indicating the growth influence factors in order of importance are temperature, pH value and bacterial loads. To study the reducing ability of the strain in different condition, we found the ability was improved when treated with glutathione and nitrate of potash and the most suitable addition ratio of glutathione is0.2%, nitrate of potash is0.4%.3-factor and3-level othoglnal tests were performed, the results indicating the reducing ability influence factors in order of importance are time, bacterial loads, concentration of sodium selenite. The optimal composition is6d culturing,12%bacterial loads and3mmol/L sodium selenite.