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Microorganisms around Coal Mines and Their Application

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A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Environmental Microbiology".

Deadline for manuscript submissions: closed (30 April 2024) | Viewed by 7127

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Special Issue Editor

Dr. Huan He

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Guest Editor

School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China
Interests: microbial community around coal mine; coal biotransformation; biogenic coal bed methane; coal-based solid waste recycling; ecological restoration of coal mine
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Coal mine provide essential fuel and resource for industrial development in human history. However, coal mining and utilization also cause a serial environmental problem. To cope with the climate change and mitigation, coal’s clean utilization and related pollution treatment attract more attention around the world. Coal mines offer habits for a large diversity of microorganism. These microbes play an essential role in many geochemical cycles around coal mine, such as sulfur and carbon cycle, organic matter decomposing, mineral weathering, and so on. The biochemical reaction process of these microorganisms provides some potential application around coal mine including harmful elements removed, high-value added products recovery, biogenic coal bed methane etc. This special issue will provide a platform to display the latest results, progress, and summary of the microorganism around coal mines and their application research in coal clean utilization, ecological remediation and so on.

Dr. Huan He
Guest Editor

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Keywords

microbial community around coal mine
bio-desulfurization of coal
bioleaching valuable elements from coal and its associated mineral
biotransformation of coal
biogenic coal bed methane
microbial treatment acid mine drainage from coal
coal mine microbial restoration

Published Papers (7 papers)

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Research

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14 pages, 3681 KiB

Open AccessArticle

Bioleaching Mercury from Coal with Aspergillus flavus M-3

by Wenqing Mao, Juan Mei, Huan He, Cheng Liu, Xiuxiang Tao and Zaixing Huang

Microorganisms 2023, 11(11), 2702; https://doi.org/10.3390/microorganisms11112702 - 03 Nov 2023

Viewed by 540

Abstract

This study focuses on the utilization of Aspergillus flavus(M-3) for the bioleaching mercury from coal, offering an alternative and environmentally to its clean utilization. The fungus was isolated from the soil near a high mercury coal mine in Lao Ying Shan (LYS), Guizhou. Utilizing direct mercury analysis, X-ray diffraction (XRD), and Fourier Transform-Infrared (FT-IR) analysis techniques, the transformation of mercury speciation, mineral components, and organic groups in the coal were analyzed before and after the bioleaching process. The findings of the study illustrated that the fungus M-3 exhibited a remarkable capacity for coal bioliquefaction and mercury leaching from LYS coal. Following a 15-day bioleaching process, a remarkable mercury leaching rate of 83.79% was achieved. Various forms of mercury speciation, including residue, organic matter, sulfide-bound, oxide-bound, exchangeable, and carbonate-bound forms, were released from the coal, with leaching rates ranging from 80.41% to 92.60%. XRD analysis indicated that the M-3 strain facilitated the dissolution of coal pyrite and the degradation of macromolecules, effectively loosening the coal structure. FT-IR analysis of raw and residual coal demonstrated the breakdown of the aromatic ring structure and introduced oxygen-containing functional groups by M-3. Overall, this study highlights the efficacy of bioliquefying coal using Aspergillus flavus (M-3) as a method for clean coal utilization while simultaneously bioleaching mercury. Full article

(This article belongs to the Special Issue Microorganisms around Coal Mines and Their Application)

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11 pages, 1320 KiB

Open AccessArticle

Metallophore Activity toward the Rare Earth Elements by Bacteria Isolated from Acid Mine Drainage Due to Coal Mining

by Stephanie Skeba, Morgan Snyder and Chris Maltman

Microorganisms 2023, 11(11), 2672; https://doi.org/10.3390/microorganisms11112672 - 31 Oct 2023

Cited by 1 | Viewed by 1154

Abstract

The field of microbe–metal interactions has been gaining significant attention. While the direct impact of metal oxyanions on bacteria has been investigated, significantly less attention has been placed on the ability of certain microbes to ‘collect’ such metal ions via secreted proteins. Many bacteria possess low-weight molecules called siderophores, which collect Fe from the environment to be brought back to the cell. However, some appear to have additional roles, including binding other metals, termed ‘metallophores’. Microbes can remove/sequester these from their surroundings, but the breadth of those that can be removed is still unknown. Using the Chromeazurol S assay, we identified eight isolates, most belonging to the genus Pseudomonas, possessing siderophore activity, mainly from sites impacted by coal mine drainage, also possessing a metallophore activity toward the rare earth elements that does not appear to be related to ionic radii or previously reported EC₅₀ concentrations for E. coli. We found the strength of metallophore activity towards these elements was as follows: Pr > Sc > Eu > Tm > Tb > Er > Yb > Ce > Lu > Sm > Ho > La > Nd > Dy > Gd > Y. This is the first study to investigate such activity and indicates bacteria may provide a means of removal/recovery of these critical elements. Full article

(This article belongs to the Special Issue Microorganisms around Coal Mines and Their Application)

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13 pages, 2651 KiB

Open AccessArticle

The Relationship between Acid Production and the Microbial Community of Newly Produced Coal Gangue in the Early Oxidation Stage

by Qi Zhu, Mengying Ruan, Zhenqi Hu, Kexin Miao and Chun Ye

Microorganisms 2023, 11(11), 2626; https://doi.org/10.3390/microorganisms11112626 - 25 Oct 2023

Cited by 1 | Viewed by 809

Abstract

Coal gangue is a solid waste formed during coal production, and the acid mine drainage it generates during open-pit storage severely pollutes the ecological environment of mining areas. Microorganisms play a crucial catalytic role in acidification, and their species and gene functions change during the oxidation process of coal gangue. In this study, the changes in microbial community structure were investigated during the initial acidification process for newly produced gangue exposed to moisture by monitoring the changes in pH, EC, sulfate ion concentration, and the iron oxidation rate of gangue leaching solutions. Moreover, the composition and functional abundance of microbial communities on the surface of the gangue were analyzed with rainfall simulation experiments and 16S rRNA sequencing. The study yielded the following findings: (1) The critical period for newly produced gangue oxidation spanned from 0~15 d after its exposure to water; the pH of leaching solutions decreased from 4.65 to 4.09 during this time, and the concentration and oxidation rate of iron in the leaching solutions remained at low levels, indicating that iron oxidation was not the main driver for acidification during this stage. (2) When the gangue was kept dry, Burkholderia spp. dominated the gangue microbial community. When the gangue was exposed to moisture, the rate of acidification accelerated, and Pseudomonas replaced Burkholderia as the dominant genus in the community. (3) In terms of gene function, the microbial community of the acidified gangue had stronger nitrogen cycling functions, and an increase in the abundance of microorganisms related to the sulfur cycle occurred after day 15 of the experiment. The microbial community in the acidified gangue had more stress resistance than the community of the newly formed gangue, but its potential to decompose environmental pollutants decreased. Full article

(This article belongs to the Special Issue Microorganisms around Coal Mines and Their Application)

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21 pages, 12915 KiB

Open AccessArticle

Influences of Four Kinds of Surfactants on Biodegradations of Tar-Rich Coal in the Ordos Basin by Bacillus bicheniformis

by Wensheng Shen, Xiangrong Liu, Chen Shi, Jie Yang, Shunsheng Zhao, Zaiwen Yang and Dan Wang

Microorganisms 2023, 11(10), 2397; https://doi.org/10.3390/microorganisms11102397 - 26 Sep 2023

Viewed by 721

Abstract

The biodegradation of tar-rich coal in the Ordos Basin was carried out by Bacillus licheniformis (B. licheniformis) under actions of four kinds of surfactants, namely, a biological surfactant (Rh), a nonionic surfactant (Triton X-100), an anionic surfactant (LAS), and a cationic surfactant (DTAB). The biodegradation rates under the actions of Triton X-100, LAS, Rh, DTAB, and the control group (without surfactant) were 59.8%, 54.3%, 51.6%, 17.3%, and 43.5%, respectively. The biodegradation mechanism was studied by examining the influences of surfactants on coal samples, bacteria, and degradation products in the degradation process. The results demonstrated that Rh, Triton X-100, and LAS could promote bacterial growth, while DTAB had the opposite effect. Four surfactants all increased the cell surface hydrophobicity (CSH) of B. licheniformis, and Triton X-100 demonstrated the most significant promotion of CSH. The order of improvement in microbial cell permeability by surfactants was DTAB > TritonX-100 > LAS > Rh > control group. In the presence of four surfactants, Triton X-100 exhibited the best hydrophilicity improvement for oxidized coal. Overall, among the four surfactants, Triton X-100 ranked first in enhancing the CSH of bacteria and the hydrophilicity of oxidized coal and second in improving microbial cell permeability; thus, Triton X-100 was the most suitable surfactant for promoting B. licheniformis’s biodegradation of tar-rich coal. The GC-MS showed that, after the action of Triton X-100, the amount of the identified degradation compounds in the toluene extract of the liquid product decreased by 16 compared to the control group, the amount of dichloromethane extract decreased by 6, and the amount of ethyl acetate extract increased by 6. Simultaneously, the contents of alkanes in the extracts of toluene and dichloromethane decreased, lipids increased, and ethyl acetate extract exhibited little change. The FTIR analysis of the coal sample suggested that, under the action of Triton X-100, compared to oxidized coal, the Har/H and A(CH₂)/A(CH₃) of the remaining coal decreased by 0.07 and 1.38, respectively, indicating that Triton X-100 enhanced the degradation of aromatic and aliphatic structures of oxidized coal. Therefore, adding a suitable surfactant can promote the biodegradation of tar-rich coal and enrich its degradation product. Full article

(This article belongs to the Special Issue Microorganisms around Coal Mines and Their Application)

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13 pages, 4930 KiB

Open AccessArticle

Microbial Communities Affected by Hydraulic Fracturing and Environmental Factors within an In Situ Coal Reservoir

by Yang Li, Jian Chen, Shuheng Tang and Zhaodong Xi

Microorganisms 2023, 11(7), 1657; https://doi.org/10.3390/microorganisms11071657 - 25 Jun 2023

Cited by 2 | Viewed by 1056

Abstract

The rise of coalbed methane bioengineering enables the conversion and utilization of carbon dioxide through microbial action and the carbon cycle. The environment of underground coal reservoirs is the result of a comprehensive effort by microorganisms. Some studies on reservoir microorganisms have progressed in laboratory conditions. However, it does not replicate the interaction between microorganisms and the environment on site. Hydraulic fracturing is an engineering technology to improve the natural permeability of tight reservoirs and is also a prerequisite for increasing biomethane production. In addition to expanding the pore and fracture systems of coal reservoirs, hydraulic fracturing also improves the living conditions of microbial communities in underground space. The characteristics of microbial communities in the reservoir after hydraulic fracturing are unclear. To this end, we applied the 16S rRNA sequencing technique to coalbed methane production water after hydraulic fracturing south of the Qinshui Basin to analyze the microbial response of the hydraulic fracturing process in the coal reservoir. The diversity of microbial communities associated with organic degradation was improved after hydraulic fracturing in the coal reservoir. The proportion of Actinobacteria in the reservoir water of the study area increased significantly, and the abundance of Aminicenantes and Planctomycetes increased, which do not exist in non-fracturing coalbed methane wells or exist at very low abundance. There are different types of methanogens in the study area, especially in fracturing wells. Ecological factors also determine the metabolic pathway of methanogens in coal seams. After hydraulic fracturing, the impact on the reservoir’s microbial communities remains within months. Hydraulic fracturing can strengthen the carbon circulation process, thereby enhancing the block’s methane and carbon dioxide circulation. The study provides a unique theoretical basis for microbially enhanced coalbed methane. Full article

(This article belongs to the Special Issue Microorganisms around Coal Mines and Their Application)

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Review

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17 pages, 1597 KiB

Open AccessReview

Roles and Regulation of Quorum Sensing of Acidophiles in Bioleaching: A Review

by Wang Luo, Yiran Li, Shiqi Chen, Yili Liang and Xueduan Liu

Microorganisms 2024, 12(3), 422; https://doi.org/10.3390/microorganisms12030422 - 20 Feb 2024

Viewed by 745

Abstract

Bioleaching has gained significant attention as a cost-effective and environmentally friendly approach for extracting metals from low-grade ores and industrial byproducts. The application of acidophiles in bioleaching has been extensively studied. Among the various mechanisms leaching microorganisms utilize, quorum sensing (QS) is pivotal in regulating their life activities in response to population density. QS has been confirmed to regulate bioleaching, including cell morphology, community structure, biofilm formation, and cell metabolism. Potential applications of QS have also been proposed, such as increasing mineral leaching rates by adding signaling molecules. This review is helpful for comprehensively understanding the role of QS in bioleaching and promoting the practical application of QS-based strategies in bioleaching process optimization. Full article

(This article belongs to the Special Issue Microorganisms around Coal Mines and Their Application)

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15 pages, 801 KiB

Open AccessReview

Research Progress and Prospects on Microbial Response and Gas Potential in the Coal Gasification Process

by Yang Li, Shuheng Tang, Jian Chen and Zhaodong Xi

Microorganisms 2023, 11(5), 1293; https://doi.org/10.3390/microorganisms11051293 - 16 May 2023

Cited by 2 | Viewed by 1456

Abstract

As an essential unconventional natural gas resource, China’s coalbed methane resources are only commercially exploited in a few areas, such as the Qinshui Basin and the Ordos. The rise of coalbed methane bioengineering makes it possible to realize the conversion and utilization of carbon dioxide through microbial action and the carbon cycle. According to the metabolic behavior of the underground microbial community, if the coal reservoir is modified, it may stimulate the microorganism to continuously produce biomethane to prolong the production life of depleted coalbed methane wells. This paper systematically discusses the microbial response to promoting microbial metabolism by nutrients (microbial stimulation), introducing exogenous microorganisms or domestication of in situ microorganisms (microbial enhancement), pretreating coal to change its physical or chemical properties to improve bioavailability, and improving environmental conditions. However, many problems must be solved before commercialization. The whole coal reservoir is regarded as a giant anaerobic fermentation system. Some issues still need to be solved during the implementation of coalbed methane bioengineering. Firstly, the metabolic mechanism of methanogenic microorganisms should be clarified. Secondly, it is urgent to study the optimization of high-efficiency hydrolysis bacteria and nutrient solutions in coal seams. Finally, the research on the underground microbial community ecosystem and biogeochemical cycle mechanism must be improved. The study provides a unique theory for the sustainable development of unconventional natural gas resources. Furthermore, it provides a scientific basis for realizing the carbon dioxide reuse and carbon element cycle in coalbed methane reservoirs. Full article

(This article belongs to the Special Issue Microorganisms around Coal Mines and Their Application)

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