A novel strictly anaerobic hyperthermophilic archaeon, strain 4213-co, was isolated from a terrestrial hot spring in the Uzon Caldera, Kamchatka (Russian Federation). Coccoid cells were present singly, in pairs, or aggregates, and occasionally were motile. The strain grew at 75-100 °C and within a pH range of 5.
View Article and Find Full Text PDFMicrobial 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.
View Article and Find Full Text PDFA novel aerotolerant anaerobic bacterium (strain M4Ah) was isolated from a terrestrial mud volcano (Taman Peninsula, Russia). Cells were small, cell-wall-less, non-motile cocci, 0.32-0.
View Article and Find Full Text PDFThe genus Natronospira is represented by a single species of extremely salt-tolerant aerobic alkaliphilic proteolytic bacterium, isolated from hypersaline soda lakes. When cells of Gram-positive cocci were used as a substrate instead of proteins at extremely haloalkaline conditions, two new members of this genus were enriched and isolated in pure culture from the same sites. Strains AB-CW1 and AB-CW4 are obligate aerobic heterotrophic proteolytic bacteria able to feed on both live and dead cells of staphylococci and a range of proteins and peptides.
View Article and Find Full Text PDFNitrate leaching from agricultural soils is increasingly found in groundwater, a primary source of drinking water worldwide. This nitrate influx can potentially stimulate the biological oxidation of iron in anoxic groundwater reservoirs. Nitrate-dependent iron-oxidizing (NDFO) bacteria have been extensively studied in laboratory settings, yet their ecophysiology in natural environments remains largely unknown.
View Article and Find Full Text PDFThe Barents Sea shelf is one of the most economically promising regions in the Arctic in terms of its resources and geographic location. However, benthic microbial communities of the northeastern Barents Sea are still barely studied. Here, we present a detailed systematic description of the structures of microbial communities located in the sediments and bottom water of the northeastern Barents Sea based on 16S rRNA profiling and a qPCR assessment of the total prokaryotic abundance in 177 samples.
View Article and Find Full Text PDFHighly 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.
View Article and Find Full Text PDFTwo strains of neutrophilic haloaloarchaea were selectively enriched from hypersaline lakes in southwestern Siberia using β-1,3-glucans as a substrate. The strains were nearly identical in their phenotypes and according to phylogenomic analysis, and represent a distant novel species group in the genus Halapricum of the family Haloarculaceae. The main phenotypic property of the novel isolates is the ability to hydrolyze and grow with the polysaccharides curdlan and pachyman.
View Article and Find Full Text PDFare widespread in various anoxic ecosystems and are considered one of the most abundant microbial groups on the earth. There are only a few reports of laboratory cultivation of , and none of the representatives of this class has been isolated in pure culture. Here, we report a sustainable cultivation of the archaeon (strain M17C) enriched from anaerobic sediment of a coastal lake.
View Article and Find Full Text PDFHaloalkaliphilic microorganisms are double extremophiles functioning optimally at high salinity and pH. Their typical habitats are soda lakes, geologically ancient yet widespread ecosystems supposed to harbor relict microbial communities. We compared metabolic features and their determinants in two strains of the natronophilic species , the only cultured representative of the class "" ().
View Article and Find Full Text PDFClimate change, desertification, salinisation of soils and the changing hydrology of the Earth are creating or modifying microbial habitats at all scales including the oceans, saline groundwaters and brine lakes. In environments that are saline or hypersaline, the biodegradation of recalcitrant plant and animal polysaccharides can be inhibited by salt-induced microbial stress and/or by limitation of the metabolic capabilities of halophilic microbes. We recently demonstrated that the chitinolytic haloarchaeon Halomicrobium can serve as the host for an ectosymbiont, nanohaloarchaeon 'Candidatus Nanohalobium constans'.
View Article and Find Full Text PDFA novel facultatively anaerobic moderately thermophilic bacterium, strain B-154 , was isolated from a terrestrial hot spring in the Baikal lake region (Russian Federation). Gram-negative, motile, spherical cells were present singly, in pairs, or aggregates, and reproduced by binary fission. The strain grew at 30-57 °C and within a pH range of 5.
View Article and Find Full Text PDFThe key microbial group involved in anaerobic methane oxidation is anaerobic methanotrophic archaea (ANME). From a terrestrial mud volcano, we enriched a microbial community containing ANME-2a, using methane as an electron donor, Fe(III) oxide (ferrihydrite) as an electron acceptor, and anthraquinone-2,6-disulfonate as an electron shuttle. Ferrihydrite reduction led to the formation of a black, highly magnetic precipitate.
View Article and Find Full Text PDFThe continental subsurface harbors microbial populations highly enriched in uncultured taxa. OPB41 is an uncultured order-level phylogenetic lineage within the actinobacterial class . OPB41 bacteria have a wide geographical distribution, but the physiology and metabolic traits of this cosmopolitan group remain elusive.
View Article and Find Full Text PDFA pure culture of alkaliphilic haloarchaeon strain AArc-S capable of anaerobic growth by carbohydrate-dependent sulfur respiration was obtained from hypersaline lakes in southwestern Siberia. According to phylogenetic analysis, AArc-S formed a new genus level branch most related to the genus Natronoarchaeum in the order Halobacteriales. The strain is facultatively anaerobic with strictly respiratory metabolism growing either by anaerobic respiration with elemental sulfur and thiosulfate as the electron acceptors or by aerobic respiration at microoxic conditions.
View Article and Find Full Text PDFMethanonatronarchaeia represents a deep-branching phylogenetic lineage of extremely halo(alkali)philic and moderately thermophilic methyl-reducing methanogens belonging to the phylum Halobacteriota. It includes two genera, the alkaliphilic Methanonatronarchaeum and the neutrophilic Ca. Methanohalarchaeum.
View Article and Find Full Text PDFAnaerobic carboxydotrophy is a widespread catabolic trait in bacteria, with two dominant pathways: hydrogenogenic and acetogenic. The marginal mode by direct oxidation to CO using an external e-acceptor has only a few examples. Use of sulfidic sediments from two types of hypersaline lakes in anaerobic enrichments with CO as an e-donor and elemental sulfur as an e-acceptor led to isolation of two pure cultures of anaerobic carboxydotrophs belonging to two genera of sulfur-reducing haloarchaea: Halanaeroarchaeum sp.
View Article and Find Full Text PDFHalorhodospira halophila, one of the most-xerophilic halophiles, inhabits biophysically stressful and energetically expensive, salt-saturated alkaline brines. Here, we report an additional stress factor that is biotic: a diminutive Candidate-Phyla-Radiation bacterium, that we named 'Ca. Absconditicoccus praedator' M39-6, which predates H.
View Article and Find Full Text PDFMicrobial communities of the Kamchatka Peninsula terrestrial hot springs were studied using radioisotopic and cultural approaches, as well as by the amplification and sequencing of and 16S rRNA genes fragments. Radioisotopic experiments with S-labeled sulfate showed that microbial communities of the Kamchatka hot springs are actively reducing sulfate. Both the cultivation experiments and the results of and 16S rRNA genes fragments analyses indicated the presence of microorganisms participating in the reductive part of the sulfur cycle.
View Article and Find Full Text PDFTerrestrial mud volcanoes (TMVs) are important natural sources of methane emission. The microorganisms inhabiting these environments remain largely unknown. We studied the phylogenetic composition and metabolic potential of the prokaryotic communities of TMVs located in the Taman Peninsula, Russia, using a metagenomic approach.
View Article and Find Full Text PDFNine pure cultures of neutrophilic haloaloarchaea capable of anaerobic growth by carbohydrate-dependent sulfur respiration were isolated from hypersaline lakes in southwestern Siberia and southern Russia. According to phylogenomic analysis the isolates were closely related to each other and formed a new species within the genus Halapricum (family Haloarculaceae). They have three types of catabolism: fermentative, resulting in H formation; anaerobic respiration using sulfur compounds as e-acceptors and aerobic respiration.
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