The effect of not-anaerobicization and discolored bacteria on uranium reduction by Shewanella sp. RCRI7

Shewanella sp. RCRI7 is a native strain capable of reducing uranium in anaerobic conditions. In order to employ this bacterium for the bioremediation, the mutual effects of uranium and the bacteria are studied in two different approaches. The optimal settings for the bacterial proliferation capacity and uranium reduction without anaerobicization of the environment, as well as the related effects of bioremediation and bacterial color under uranium-reducing conditions, have been investigated in this study. Uranium reduction procedure was analyzed using XRD, spectrophotometry and ICP-AES. In addition, the uranium???s effect on the population of the firstgeneration of the bacteria as well as the color and growth of the second-generation were investigated using neobar lam and CFU (Colony Forming Unit), respectively. Uranium toxicity reduced the population of nonanaerobicized bacteria more than the anaerobicized bacteria after one day of incubation, while the amount of uranium extracted by the bacteria was almost the same. In both situations, the bacteria were able to reduce uranium after two weeks of incubation. In addition to the cell counts, uranium toxicity disrupts the growth and development of healthy second-generation anaerobicized bacteria, as created creamy-colored colonies grow slower than red-colored colonies. Furthermore, due to malfunctioning cytochromes, unlike red bacteria, creamycolored bacteria were unable to extract the optimum amount of uranium. This study reveals that reduced uranium can be produced in a deprived environment without anaerobicization. Creamy-colored Shewanella can remove soluble uranium, however the most effective bacteria have red cytochromes. These findings represent a big step forward in the industrialization of uranium bioremediation.

Automated summary

The native strain Shewanella sp. RCRI7 can reduce uranium in anaerobic conditions. This study investigated the mutual effects of uranium and the bacteria and found that uranium reduced the population of nonanaerobicized bacteria and affected the growth and development of the anaerobicized bacteria. The study also revealed that creamy-colored Shewanella can remove soluble uranium, but bacteria with red cytochromes are the most effective.