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2. Diversity, Methane Oxidation Activity, and Metabolic Potential of Microbial Communities in Terrestrial Mud Volcanos of the Taman Peninsula.

Author

Slobodkin, Alexander I., Rusanov, Igor I., Slobodkina, Galina B., Stroeva, Aleksandra R., Chernyh, Nikolay A., Pimenov, Nikolai V., and Merkel, Alexander Y.

Subjects
MUD volcanoes, MICROBIAL communities, METHANOTROPHS, RADIOACTIVE tracers, METHANE
Abstract

Microbial communities of terrestrial mud volcanoes are involved in aerobic and anaerobic methane oxidation, but the biological mechanisms of these processes are still understudied. We have investigated the taxonomic composition, rates of methane oxidation, and metabolic potential of microbial communities in five mud volcanoes of the Taman Peninsula, Russia. Methane oxidation rates measured by the radiotracer technique varied from 2.0 to 460 nmol CH4 cm−3 day−1 in different mud samples. This is the first measurement of high activity of microbial methane oxidation in terrestrial mud volcanos. 16S rRNA gene amplicon sequencing has shown that Bacteria accounted for 65–99% of prokaryotic diversity in all samples. The most abundant phyla were Pseudomonadota, Desulfobacterota, and Halobacterota. A total of 32 prokaryotic genera, which include methanotrophs, sulfur or iron reducers, and facultative anaerobes with broad metabolic capabilities, were detected in relative abundance >5%. The most highly represented genus of aerobic methanotrophs was Methyloprofundus reaching 36%. The most numerous group of anaerobic methanotrophs was ANME-2a-b (Ca. Methanocomedenaceae), identified in 60% of the samples and attaining relative abundance of 54%. The analysis of the metagenome-assembled genomes of a community with high methane oxidation rate indicates the importance of CO2 fixation, Fe(III) and nitrate reduction, and sulfide oxidation. This study expands current knowledge on the occurrence, distribution, and activity of microorganisms associated with methane cycle in terrestrial mud volcanoes. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Phenotypic and genomic characterization of the first alkaliphilic aceticlastic methanogens and proposal of a novel genus Methanocrinis gen.nov. within the family Methanotrichaceae

Author

Khomyakova, Maria A. (author), Merkel, Alexander Y. (author), Slobodkin, Alexander I. (author), Sorokin, Dimitry Y. (author), Khomyakova, Maria A. (author), Merkel, Alexander Y. (author), Slobodkin, Alexander I. (author), and Sorokin, Dimitry Y. (author)

Abstract

Highly purified cultures of alkaliphilic aceticlastic methanogens were collected for the first time using methanogenic enrichments with acetate from a soda lake and a terrestrial mud volcano. The cells of two strains were non-motile rods forming filaments. The mud volcano strain M04Ac was alkalitolerant, with the pH range for growth from 7.5 to 10.0 (optimum at 9.0), while the soda lake strain Mx was an obligate alkaliphile growing in the pH range 7.7–10.2 (optimum 9.3–9.5) in the presence of optimally 0.2–0.3 M total Na+. Genomes of both strains encoded all enzymes required for aceticlastic methanogenesis and different mechanisms of (halo)alkaline adaptations, including ectoine biosynthesis, which is the first evidence for the formation of this osmoprotectant in archaea. According to 16S rRNA gene phylogeny, the strains possessed 98.3–98.9% sequence identity and belonged to the obligately aceticlastic genus Methanothrix with M. harundinaceae as the most closely related species. However, a more advanced phylogenomic reconstruction based on 122 conserved single-copy archaeal protein-coding marker genes clearly indicated a polyphyletic origin of the species included in the genus Methanothrix. We propose to reclassify Methanothrix harrundinacea (type strain 8AcT) into a new genus, Methanocrinis gen. nov., with the type species Methanocrinis harrundinaceus comb. nov. We also propose under SeqCode the complete genome sequences of strain MxTs (GCA_029167045.1) and strain M04AcTs (GCA_029167205.1) as nomenclatural types of Methanocrinis natronophilus sp. nov. and Methanocrinis alkalitolerans sp. nov., respectively, which represent other species of the novel genus. This work demonstrates that the low energy aceticlastic methanogenesis may function at extreme conditions present in (halo)alkaline habitats., BT/Environmental Biotechnology

Published
2023
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16. PCR-based identification of hyperthermophilic archaea of the family Thermococcaceae

Author

Slobodkina, Galina B., Chernyh, Nikolai A., Slobodkin, Alexander I., Subbotina, Irina V., Bonch-Osmolovskaya, Elizaveta A, and Lebedinsky, Alexander V.

Subjects
Ribosomal RNA -- Research, Microbiological research, Biological sciences
Abstract

A method for rapid detection and identification of hyperhtermophilic archaea of the family Thermococcaceae based on PCR amplification of 16 rRNA gene fragments with two primers was developed and used for identification of new isolates.

Published
2004

17. Microbial diversity and autotrophic activity in Kamchatka hot springs

Author

Merkel, Alexander Yu., primary, Pimenov, Nikolay V., additional, Rusanov, Igor I., additional, Slobodkin, Alexander I., additional, Slobodkina, Galina B., additional, Tarnovetckii, Ivan Yu., additional, Frolov, Evgeny N., additional, Dubin, Arseny V., additional, Perevalova, Anna A., additional, and Bonch-Osmolovskaya, Elizaveta A., additional

Published
2016
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23. The Geoglobus acetivorans Genome: Fe(III) Reduction, Acetate Utilization, Autotrophic Growth, and Degradation of Aromatic Compounds in a Hyperthermophilic Archaeon

Author

Mardanov, Andrey V., primary, Slododkina, Galina B., additional, Slobodkin, Alexander I., additional, Beletsky, Alexey V., additional, Gavrilov, Sergey N., additional, Kublanov, Ilya V., additional, Bonch-Osmolovskaya, Elizaveta A., additional, Skryabin, Konstantin G., additional, and Ravin, Nikolai V., additional

Published
2015
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26. Fe(III) as an electron acceptor for H2 oxidation in thermophilic anaerobic enrichment cultures from geothermal areas.

Author

Slobodkin, Alexander I. and Wiegel, Juergen

Abstract

Six sustainable enrichment cultures of thermophilic H2-oxidizing microorganisms utilizing Fe(III) as an electron acceptor were obtained from geothermally heated environments located on two continents (America, Eurasia) and on islands in the Northern (Iceland) and Southern (Fiji) hemispheres, demonstrating the wide distribution of these microorganisms. The main products of amorphic Fe(III) oxide reduction were magnetite and siderite. The observed temperature range for Fe(III) reduction in growing cultures was from 55°C to 87°C, extending the known limits for growth of Fe(III)-reducing microorganisms producing extracellular magnetite to nearly 90°C. [ABSTRACT FROM AUTHOR]

Published
1997
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