Response and Dynamic Change of Microbial Community during Bioremediation of Uranium Tailings by Bacillus sp.

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.

Optimization of Environmental Conditions for Microbial Stabilization of Uranium Tailings, and the Microbial Community Response

“…When the pH of the system is close to neutral, the microbial activity is higher under the premise that all other environmental conditions are consistent, thus increasing the higher stabilization rate of uranium. In addition, the control group (aseptic inoculation experiments) showed that the unstable uranium remained at a relatively high level after the leaching effect of medium in our previous study ( Tang et al, 2021 ). Therefore, it can be inferred that uranium conversion is mainly based on microbial metabolism.…”

“…The uranium tailings used in this experiment were collected from a uranium tailings repository located in Fuzhou city, Jiangxi Province, southeast of China. Moreover, the chemical properties of the sampled tailings were shown in our previous study (Tang et al, 2021), as U, Mn, Fe, Ca, and SO 4 2− were the main compositions. The sulfate-reducing bacteria and phosphate-solubilizing bacteria used in this study were preserved in the National Engineering Laboratory of Biohydrometallurgy, China.…”

“…Uranium not only is radioactive, which can cause radiation to the human body, but also has strong chemical toxicity ( Lu et al, 2018 ; Selvakumar et al, 2018 ). In the natural environment, uranium will cause the decrease in cellular activity and metabolic activity of soil microorganisms after entering soil and affect the whole soil ecosphere; once in the body, uranium and its compounds are apt to bind with phosphorylated peptides, causing damage to the kidneys, bones, and brain ( Tang et al, 2021 ). Undoubtedly, the world will face a more serious situation of soil contaminated by uranium in the future with the further development and application of nuclear energy.…”

Applying EDTA in Chelating Excess Metal Ions to Improve Downstream DNA Recovery from Mine Tailings for Long-Read Amplicon Sequencing of Acidophilic Fungi Communities

“…Mine tailing samples were collected at three different tailing storage sites in Krugersdorp, Gauteng province, South Africa (mixed tailing and tailing A—26.132750, 27.711464, tailing B—26.133074, 27.767206, and tailing C—26.135979, 27.740172). A diagonal sampling method was used [ 25 ], and the samples were collected at various depths: depth 1: 0–15 cm, depth 2: 15–30 cm, and depth 3: 30–45 cm, while mixed tailings (mixed tailings before re-processing) were collected on the surface. Each depth’s samples were combined (for instance, all 0–15 cm depth samples were combined to form one sample per sampling site), and from each tailing storage site, a total of three samples were obtained.…”

Characteristics of groundwater microbial communities and the correlation with the environmental factors in a decommissioned acid in-situ uranium mine

“…At present, there are many studies on the correlation between microbial community structure and environmental factors in uranium mining area (Cho et al, 2012;Green et al, 2012;Coral et al, 2018), including active acid leaching uranium aquifer (Coral et al, 2018), uranium-contaminated tailing ponds (Dhal, 2018), former leaching heap area (~26 years; Sitte et al, 2015), and decommissioned uranium mine aquifers characterized by NO 3 − and uranium contamination (Cho et al, 2012;Green et al, 2012). In addition, many studies have also reported the dynamic changes of microbial communities during bioremediation (Zhang et al, 2017;Tang et al, 2021). However, there are limited studies about the characteristics of microbial communities in groundwater of decommissioned acid in-situ uranium mine.…”