Microbial biomass, diversity of culturable bacteria and micromycetes, and the number of functional nitrogen cycle genes in the supraglacial systems of the Aldegonda and Bertil glaciers have been studied. The biomass of microorganisms varies from 2.54 to 722 µg/g substrate. It is shown for the first time that the major part (78.7–99.8

Microbial biomass, diversity of cultivated bacteria and micromycetes, as well as the number of functional nitrogen cycle genes in the supraglacial systems of the Aldegonde and Bertel glaciers were studied. Biomass of microorganisms varied from 2.54 to 722 µg/g of substrate. It has been shown for the first time that the majority (78.7–99.8%) of the microbial biomass of supraglacial objects is represented by fungi rather than prokaryotes. Main part (from 70 to 90%) of the fungal biomass was mycelium, the length of which varied from 6.70 to 537.51 m/g of substrate. The number of prokaryotes varied from 2.4 × 108 to 1.95 × 109 cells/g of substrate. The length of actinomycete mycelium varied from 2.6 to 62.61 m/g of substrate. The abundance of cultivated bacteria and actinomycetes varied from 3.3 × 104 to 1.2 × 106 CFU/g of substrate, and that of micromycetes varied from 2.2 × 101 to 1.7 × 104 CFU/g of substrate. Bacteria of the genera Arthrobacter, Bacillus, Rhodococcus, and Streptomyces, as well as micromycetes of the genera Antarctomyces, Cadophora, Hyphozyma, Teberdinia and Thelebolus dominated. Micromycetes Antarctomyces psychrotrophicus, Hyphozyma variabilis and Teberdinia hygrophila were found in Svalbard for the first time. The number of amoA genes in ammonium-oxidizing bacteria varied from 5.33×106 to 4.86 × 109; nitrogen fixation genes nifH, from 9.89 × 107 to 9.81 × 1010; nirK denitrification genes, from 4.82 × 107 to 3.34 × 1010 gene copies/g of substrate. The results obtained indirectly indicate the leading role of fungi in the microbiome of the supraglacial objects of Svalbard and the significant contribution of prokaryotes to the emission of greenhouse gases from them.

For the first time, a comprehensive assessment of the biological activity of the supraglacial systems of the IGAN Glacier—the largest glacier of the Polar Urals—was carried out. The stocks and structure of microbial biomass were estimated using luminescent microscopy and substrate-induced respiration methods; basal respiration, the intensity of methanogenesis and nitrogen fixation, the number of copies of ribosomal genes of microorganisms (bacteria, archaea, and fungi), and the numbers (CFU/g soil) of cultivated micromycetes, saprotrophic bacteria, and actinomycetes were also studied. The highest biological activity was found in the supraglacial zone, and the lowest—along its periphery and in the near periglacial zone. In all zones of the glacier, Geomyces pannorum, G. vinaceus, and Teberdinia hygrophila dominated among micromycetes, and representatives of the Arthrobacter and Bacillus genera dominated among bacteria. The microbiome structure of supraglacial bodies depended on their location on the glacier and differed significantly at the periphery and in the center of the supraglacial zone, as well as in comparison with soils and sediments in the adjacent periglacial landscape. The material released from the glacier body with a high content of organic matter affects the biological activity of supraglacial microbial communities.

Assessment of the response of soil microbial communities, performing important ecological and biospheric functions, to natural or anthropogenic impacts is one of the promising approaches to solve the problems of stress resilience of ecosystems. A model experiment with soddy-podzolic soil (Eutric Albic Retisol (Abruptic, Loamic)) has shown the inhibitory effect of ammonium and the stimulating effect of lanthanum on methane oxidation by soil microorganisms. The application of ammonium and lanthanum reduced the taxonomic diversity of the soil bacterial community and changed its structure: the relative content of gram-positive bacteria of Actinobacteriota and Bacillota phyla decreased, while the portion of gram-negative bacteria of the phylum Pseudomonadota increased. Applied lanthanum causes a significant (by several orders of magnitude) rise in the relative content of methanotrophs of Methylobacter genus and of obligate methylotrophs of Methylotenera genus in the community. The results of this work may be used to develop approaches for the control of the activity of the soil methane filter and of the accompanying microbiota.

A comprehensive quantitative and qualitative characterization of prokaryotic communities of solid atmospheric fallout (dust aerosol) and soils in the areas with different anthropogenic loads within the territory of Moscow was obtained. The total number of bacteria in the studied samples of solid atmospheric fallouts (SAF) was lower than the number of bacteria in soil samples; actinomycete mycelium was not found in dust samples, although it was found in soil samples. The number of culturable saprotrophic bacteria in dust samples was an order of magnitude lower than in Urbic Technosols taken at the same plots. Representatives of the genus Micrococcus dominated the culturable bacteria in the dust aerosols, while representatives of the phylum Proteobacteria dominated in soils. Representatives of the Enterobacteriaceae family were found in the dust samples, among which there were species that are potential human pathogens. The maximum biodiversity of bacteria of the Enterobacteriaceae family was recorded in the dust samples taken in areas with increased anthropogenic and transport load. The sanitary-indicative bacterium Escherichia coli was found in all samples of the dust and Urbic Technosols; its content varied from 10 to 100 CFU/g, which corresponds to the moderate degree of epidemic danger. Ecological indices calculated for prokaryotic communities in situ (barcoding of the 16S rRNA gene) indicate a lower taxonomic diversity of SAF prokaryotic communities in comparison with communities of closely spaced Urbic Technosols.

— A comprehensive study of prokaryotic communities of zonal Ferralsols and intrazonal Fluvisols, as well as associated leaf litter and “suspended” soil from epiphytic fern baskets was carried out. The maximum number of bacteria determined by the direct luminescence method (5.59 billion cells) was found in the samples of Fluvisols, while the lengths of fungal (2038 m/g) and actinomycete (1086 m/g) mycelia were the largest in the mountainous Ferralsols. Bacteria of the genus Streptomyces included in the saprotrophic bacterial complex of the studied substrates made a significant contribution to the destruction of plant material. The bacteria of the phyla Firmicutes (80%) and Proteobacteria (15%) predominated in the prokaryotic community of the zonal Ferralsols, while the phyla Proteobacteria (51%) and Actinobacteria (38%) dominated in the sample of the “suspended” soil. The phyla Chloroflexi, Acidobacteria, Bacteroidetes, and Cyanobacteria were significantly less represented. Against the background of significant differences between the studied prokaryotic communities at the level of genera, they were characterized by similar functional groups of microorganisms: xenobiotic decomposers, nitrogen cycle bacteria, extremophiles, as well as bacteria that inhibit the growth of micromycetes. The metabolically active part of the prokaryotic community represented by the phyla Proteobacteria, Actinobacteria, and Acidobacteria, was the highest in the “suspended” soil and the least active in the leaf litter and A horizon of Ferralsols, which correlated with the high abundance of these phyla and the significant taxonomic diversity of bacteria in this locus. Functional genes nifH and alkB encoding nitrogenase and alkane-hydroxylase, respectively, were detected in all studied substrates. The number of copies of functional genes was the highest in the “suspended” soil sample, which makes this locus promising for isolating strains with a high biotechnological potential.

Microbiomes of strongly skeletal residual calcareous pelozems (Skeletal Leptosols (Loamic)), carbopetrozems (Calcaric Leptosols (Protic)), petrozems (Skeletal Leptosols (Protic)), and cryozems (Oxyaquic Cryosols (Loamic)) in the north of Novaya Zemlya were studied by the methods of molecular biology. The number of copies of 16S rRNA genes was small and ranged from 2.30 × 107 to 1.63 × 109 gene copies/g soil for archaea and from 3.47 × 108 to 2.26 × 1011 gene copies/g soil for bacteria; the number of copies of ribosomal genes ITS rRNA of fungi varied from 8.87 × 106 to 7.56 × 109 gene copies/g soil. The content of copies of ribosomal genes of all groups of microorganisms sharply decreased down the soil profiles. Bacteria predominated among prokaryotes (up to 90%). The greatest abundance (20%) was manifested by the phyla Proteobacteria, Actinobacteria, and Acidobacteria; the abundances of Bacteroidetes, Firmicutes, Verrucomicrobia, Gemmatimonadetes, and Chloroflexi were about 1–10%. The Archaea domain represented mainly by the Ferroplasma genus (phylum Euryarchaeota), accounted for ≤4% of prokaryotes. The taxonomic diversity of prokaryotes increased down the soil profiles and reached maximum values in the suprapermafrost horizons, where the number of candidate phyla typical of marine ecosystems—Latescibacteria, Tectomicrobia, Parcubacteria, Saccaribacteria, Hydrogenedentes, Peregrinibacteria, Ignavibacteria, and Gracilibacteria—was high.

Epifluorescence microscopy revealed the presence of bacteriophages in all samples of the studied soils (Haplic Chernozem, Albic Retisol (Cutanic, Siltic), Haplic Kastanozem, Fluvisol (Loamic, Humic)), Limnic Fluvisol, Dystric Fibric Histosol, Histic Leptosol, and Arenosol). The number of bacteriophages counted using the SYBR Green I dye was significant: 0.34–5.7 billion units/g soil. Transmission electron microscopy was used to determine the icosahedral, caudate, and filamentous morphotypes of bacteriophages. Comparison of the amount of bacteriophages and bacteria showed that the number of phages in the studied soil samples was slightly lower as compared to bacteria (except for the samples from Chernozem and from the Antarctic Arenosol, where the number of phages slightly exceeded that of bacteria). The ratio between the numbers of bacteriophages and bacteria varied from 0.16 to 1.67. The number of cells of gram-negative and gram-positive bacteria was determined using the L7005 dye and compared with the number of bacteriophages in samples of Histosol and Kastanozem. The predomination of gram-negative bacteria (61% of the total number of bacteria) was recorded. The number of phages in the waterlogged biotope (Histosol) was three times higher than in the dry biotope (Kastanozem). The revealed high abundance and significant morphological diversity of phages enable us to suggest their particular role in the regulation of the number of bacteria in soils.

— Complexes of cultured saprotrophic bacteria and yeasts from different components of soil constructions (humus soil horizon and peat) were studied simultaneously with the assessment of auxin-producing activity (synthesis of 3-indolylacetic acid, IAA), of some bacteria and yeast strains isolated. The study was carried out at the stage of laying two variants of constructions in Syktyvkar, formed from components of local origin (variant 1) and imported components (humus soil horizon, Moscow, Seliger-agro peat, Tver region) (variant 2). The taxonomic structures of microbial complexes isolated from the studied substrates were very similar. At the same time, the components of variant 1 had a greater diversity of cultivated saprotrophic bacteria ( Bacillus ) species resistant to adverse environmental conditions, as well as the presence of the psychrophilic basidiomycete yeast Leucosporidium scottii , which was not found in the components of variant 2. The average IAA production by the yeast strains and saprotrophic bacteria was 647.6 µg/L and 741.3 µg/L, respectively. The highest IAA concentrations were found in the culture liquid of the yeast Tausonia pullulans (strain Y-6, 3362.6 µg/L) isolated from the humus soil layer of variant 1 and the two saprotrophic bacteria Flavobacterium рsychrophilum (strain B-7, 2616.8 µg/L; B-5, 1056.3 µg/L) isolated from the humus soil horizon in variant 1 and from the peat of variant 2. For strains of the yeast Leucosporidium scottii and the cultivated saprotrophic bacteria Flavobacterium psychrophilum, the ability to synthesize IAA was demonstrated for the first time.

— While lanthanum is known to regulate the metabolism of microorganisms using single-carbon compounds, there is no information about its effect on soil communities. This is the first report on response of methanotrophic communities to the introduction of lanthanum, determined using high-throughput sequencing of the 16S rRNA genes in experiments with soil microcosms. It was found that after one and two months after the introduction of lanthanum salts the proportion of Methylobacter in the total pool of sequences increased (up to 9 and 15%, respectively). At the same time, the content of methylotrophic Methylotenera increased up to 10 and 19%, respectively. Thus, lanthanum was found to stimulate the formation of Methylobacter − Methylotenera associations under elevated methane content in the soil, which may affect the contribution of agrosoils to the regulation of methane content in the atmosphere.

The quantitative and qualitative characteristics are given of the soil prokaryotic communities in the Dystric Fluvisol, litter, and "suspended soil" in epiphyte baskets. The number of bacteria (direct luminescence method) varied from 1.1 to 2.6 billion cells/g soil and was the highest in the suspended soil sample and lower in the litter and A and AB horizons of Dystric Fluvisol (brown meadow alluvial soil). Proteobacteria, Actinobacteria, and Acidobacteria predominated in the prokaryotic community (at the phylum level); Chloroflexi, Firmicutes, and Verrucomicrobia were found in smaller amounts; the content of Nitrospirae, Planctomycetes, and Gemmatimonadetes was even lower. Representatives of the Archaea domain were found in the A horizon and in the suspended soil. Their content was significantly lower than that of the Bacteria domain and did not exceed 1%. Archaea were represented by the Thaumarchaeota and Euryarchaeota phyla in the A horizon and by Thaumarchaeota and Woesearchaeota phyla in the suspended soil. Based on the calculated ecological indices (alpha and beta diversity, measures of similarity by Bray-Curtis metrics and weighted UniFrac), it was shown that the microbiome of the suspended soil was closer to the microbiome of A horizon of Dystric Fluvisol than to the microbiome of litter. The metabolically active part of the prokaryotic community represented by the Proteobacteria, Actinobacteria, and Acidobacteria phyla reached its maximum in the suspended soil and was lower in the litter and A horizon of Dystric Fluvisol, and this correlated with the high abundance of these phyla and the significant taxonomic diversity of bacteria in this locus. Functional genes (nifH and alkB) were detected in all studied substrates. The number of copies of functional genes was the highest in the suspended soil sample, which makes this locus promising for isolating the strains with high biotechnological potential.

The abundance and taxonomic diversity of actinomycetes in soils and plant litter in the Pu Hoat Nature Reserve of Central Vietnam were estimated. The number of mycelial actinobacteria in the studied substrates varied from 2.0 × 104 to 9.2 × 106 CFU/g. The largest number was recorded in the litter of the broadleaf forest in the Zut Suoi River valley. The length of the actinomycetal mycelium determined using direct luminescence microscopy varied from 178 to 800 m/g. The length of mycelium in the alluvial soils under broadleaf forest (Fluvisols) and in the mountain red-yellow ferralic soils under coniferous forest (Ferralsols) did not differ. The dominant species in the actinomycetal complex of the studied substrates were streptomycetes of sections Cinereus and Albus of the Achromogenes, Chromogenes, and Albus series. High taxonomic diversity was noted in the “suspended” soil from the baskets of epiphytes of the family Dryopteridaceae. Analysis of growth in the media with different pH values demonstrated the dominance of acidophilic forms of actinomycetes in the studied tropical soils. The study of temperature range of growth of the isolated cultures made it possible to classify them as thermotolerant and optionally thermophilic bacteria. The capacity for cellulose decomposition and the high antibiotic activity of pure cultures of actinomycetes from the studied soils attest to their considerable biotechnological potential.

Urban soils, differing in the intensity of anthropogenic impacts, were studied in several largest (Krasnodar), large (Sochi and Simferopol), and moderately large (Maikop) cities of southern Russia. The obtained data on the diversity of bacterial complexes revealed that urban soils with high anthropogenic load (Sochi, Simferopol, and Krasnodar) undergo considerable transformation of natural bacterial complexes with a sharp increase in representatives of Enterobacteriaceae family. Along with microorganisms indicative of the sanitary status of urban soils ( E. coli and En. faecalis ) the soils also contain bacteria of Klebsiella , Enterobacter , Citrobacter , and Serratia genera; some of their species may cause intestinal and allergic diseases. In the urban soil of Sochi, spores of sulfite-reducing Clostridia , including Clostridium perfringens, have been found. In the urban soil of Maikop with the lowest population density among the studied cities, changes in the structure of natural bacterial complexes are virtually absent. The abundances of sanitary-indicative microorganisms ( Escherichia coli and Enterococcus faecalis ) in urban soils of all the studied cities, except for Maikop, exceeded the normative parameter for sanitary-safe clean soils (<10 CFU/g soil).

— High-throughput sequencing of 16S rRNA genes was used to investigate the taxonomic diversity of the bacterial community inhabiting the fruiting bodies of the myxomycete Lycogala еpidendrum . Members of 31 bacterial genera belonging to six phyla were revealed. The phylum Proteobacteria predominated in the microbiome, with Pseudomonas and Luteibacter as predominant genera. Analysis of the taxonomic diversity of bacterial communities revealed significantly lower diversity in the L. epidendrum community, compared to those of brushwood and litter adjacent to the fruiting bodies. This is an indication of a selective role of the myxomycete fruiting body in respect to the phylum Proteobacteria and especially to the genera Pseudomonas and Luteibacter .

Abundance and diversity of cultivated bacteria in saprotrophic soil complexes were monitored for two years on the territory of one of the large industrial cities of the European North of Russia, Syktyvkar. The analysis was carried out before and after quarantine due to the COVID-19 pandemic. The city of Syktyvkar is characterized by a high population and intensive anthropogenic pressure. According to the total indicators of the current state of the environmental components, it should belong to the tense category, by environmental standards. Studies were conducted in 2019–2020. Topsoils (0–10 cm) of urbanozems and horizon A in the park area in the urban space, as well as zonal undisturbed podzolic soil, were analyzed. Comparison of the two-year monitoring results demonstrated a marked increase in the number and diversity of saprotrophic bacterial complexes in 2020 in both urban and control soils (topsoil, 0–10 cm). Due to a sharp and prolonged decrease in the anthropogenic impact on the environment during quarantine measures, content of the bacteria of the families Enterobacteriaceae including sanitary-indicative ( Escherichia coli , Enterococcus faecalis ) and opportunistic and allergenic ( Enterobacter agglomerans , Citrobacter europaeus , Klebsiella oxytoca , Serratia marcescens , etc.) in the urbanozems decreased. This can be considered as a manifestation of the soil’s ability to “self-remediate” during a decrease in anthropogenic impact on the environment.

In a model experiment, the transformation of microbial complexes of cultivated saprotrophic bacteria and yeasts during freezing-thawing was studied in various natural substrates that are used to create soil constructions for urban landscaping and for growing herbaceous plants. The number of saprotrophic bacteria and yeasts depended both on the type of substrate and on temperature changes during freezing-thawing. At the stage of freezing of peat and soil (arable horizon) to 0 and –5°C and at the subsequent stage of thawing to 0°C, a significant increase in yeast number was registered. The maximum number of yeasts in soil and peat was 5.1 log (CFU/g). In contrast to the number of yeasts, number of saprotrophic bacteria in soil and peat was characterized by a sharp decrease when the substrate temperature was negative and peaked at 19–22 and 10°C, respectively. The maximum bacterial number in soil and peat was 7.5 and 8.0 log (CFU/g), respectively. In sand, number of both saprotrophic bacteria and yeasts did not depend on the temperature and was 5.0 log (CFU/g) for bacteria and 3.4 log(CFU/g) for yeasts at all stages of the freezing-thawing cycles. In total, 15 saprotrophic bacterial species and 29 yeast species were isolated from different components of soil constructions. At the maximum temperature of freezing in the cycles (–5°C), three bacterial species with psychrophilic properties (Flavobacterium psychrophilum) and the ability to form endospores resistant to various adverse effects (Bacillus subtilis, B. megaterium) were isolated from soil and peat. Among the yeasts isolated from soil and peat at negative temperature and also having psychrophilic properties were Candida sake, Rhodotorula glutinis, Rh. mucilaginosa, and Solicoccozyma terricola. Bacteria with psychrophilic properties, F. psychrophilum and Pseudomonas fluorescens, as well as two species of bacilli, Bacillus subtilis and B. megaterium were revealed in sand at negative temperatures. Only one yeast species, Debaryomyces hansenii, capable of surviving stress conditions in the form of ascospores, was isolated from sand at –5°C. The effect of short-term temperature drops on the microbial communities’ number and diversity dynamics in soil constructions in a model experiment showed that specialized soil constructions were able to “tolerate” short-term temperature stress drops typical of the spring and autumn period, restoring the number of initial populations after cessation of the negative impacts. This also indicates development of the soil constructions in the process of functioning, rather than their rapid degradation.