Abstract
Thermal ecosystems associated with areas of underground burning coal seams are rare and poorly understood in comparison with geothermal objects. We studied the microbial communities associated with gas vents from the coal-fire in the mining wastes in the Kemerovo region of the Russian Federation. The temperature of the ground heated by the hot coal gases and steam coming out to the surface was 58 °C. Analysis of the composition of microbial communities revealed the dominance of Ktedonobacteria (the phylum Chloroflexi), known to be capable of oxidizing hydrogen and carbon monoxide. Thermophilic hydrogenotrophic Firmicutes constituted a minor part of the community. Among the well-known thermophiles, members of the phyla Aquificae, Deinococcus-Thermus and Bacteroidetes were also found. In the upper ground layer, Acidobacteria, Verrucomicrobia, Actinobacteria, Planctomycetes, as well as Proteobacteria of the alpha and gamma classes, typical of soils, were detected; their relative abundancies decreased with depth. The phylum Verrucomicrobia was dominated by Candidatus Udaeobacter, aerobic heterotrophs capable of generating energy through the oxidation of hydrogen present in the atmosphere in trace amounts. Archaea made up a small part of the communities and were represented by thermophilic ammonium-oxidizers. Overall, the community was dominated by bacteria, whose cultivated relatives are able to obtain energy through the oxidation of the main components of coal gases, hydrogen and carbon monoxide, under aerobic conditions.
Highlights
Studies of thermophilic microorganisms that survive and develop at extreme temperatures for ordinary life have expanded our understanding of the diversity of microorganisms, their evolution, and mechanisms of adaptation to extreme environmental conditions [1,2].Most research on thermophiles has focused on thermal ecosystems associated with volcanic activity, such as hot springs and deep-sea hydrothermal vents, or biotechnologically important objects, such as high-temperature bioreactors, etc
The phenomena of underground burning coal seams are quite common in nature and are found in Australia, Germany, USA (Pennsylvania), China, Russia, India and other countries [3]
Ground samples were taken at an abandoned open coal pit in the area of underground coal fire
Summary
Most research on thermophiles has focused on thermal ecosystems associated with volcanic activity, such as hot springs and deep-sea hydrothermal vents, or biotechnologically important objects, such as high-temperature bioreactors, etc. In addition to volcanic activity, the natural combustion of fossil hydrocarbons and coal can lead to the formation of thermal ecological niches. The phenomena of underground burning coal seams are quite common in nature and are found in Australia, Germany, USA (Pennsylvania), China, Russia, India and other countries [3]. Such underground fires can last for centuries, for example, a coal seam in Dudweiler (Saar, Germany) has been burning since 1668. An example of long-term natural underground coal fire is Burning Mountain in Australia [4], the burning time of which is estimated to be approximately 6000 years old
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