Abstract
Bacillus sp. is widely used in the remediation of uranium-contaminated sites. However, little is known about the competitive process of microbial community in the environment during bioremediation. The bioremediation of uranium tailings using Bacillus sp. was explored, and the bacterial community was analyzed by high-throughput sequencing at different stages of remediation. Bacillus sp. reduced the leaching of uranium from uranium tailings. The lowest uranium concentration was 17.25 μg/L. Alpha diversity revealed that the abundance and diversity of microorganisms increased with the extension of the culture time. The microbial abundance and diversity were higher in the treatment group than in the control group. The dominant species at the phyla level were Firmicutes and Proteobacteria in the uranium tailings environment, whereas the phylum of Proteobacteria was significantly increased in the treatment group. Based on the genus level, the proportions of Arthrobacter, Rhodococcus and Paenarthrobacter decreased significantly, whereas those of Clostridium sp., Bacillus and Pseudomonas increased dramatically. Hence, the remediation of uranium contamination in the environment was due to the functional microorganisms, which gradually became the dominant strain in the treatment, such as Desulfotomaculum, Desulfosporporosinus, Anaerocolumna, Ruminiclostridium and Burkholderia. These findings provided a promising outlook of the potential for remediation strategies of soil contaminated by uranium. The dynamic characteristics of the microbial community are likely to provide a foundation for the bioremediation process in practice.
Highlights
We investigated the microbial diversity and the responses of the components of microbial communities to the introduction of Bacillus sp. for the remediation of uranium tailings
The Source of Bacteria and Medium. This strain identified as Bacillus sp. was initially isolated and purified from the uranium tailings pile in southern of China, and preserved in National Engineering Laboratory of Biohydrometallurgy, GRINM Group
The concentration of uranium in the leaching solution decreased from 433.28 μg/L
Summary
Uranium in the environment exists in U(IV) and U(VI) forms, and the U(VI) has higher solubility and toxicity with the type of UO2 2+ [2]. Uranium exerts radioactive and chemical toxicities, and the chemical toxicity of uranium is far more harmful to the human body than the radioactive radiation; chemical toxicity induces a variety of diseases or cause mutations, aberrations and even 4.0/). The uranium pollution problem has gained worldwide attention because of its high toxicity and long-term accumulative behavior. The remediation methods for uranium pollution include physical-chemical methods and bioremediation. Compared with traditional physical-chemical methods, bioremediation is environmentally friendly and characterized by low cost, simple operation, and low environmental disturbance; it is considered as a potential remediation method in pollution control [5]. On uranium contaminated area, and on the removal rate of uranium [6,7]. Beazley et al [8]
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