O. E. Marfenina

The role of microorganisms in the ecological functions of soils

The results of long-term investigations performed by researchers from the Department of Soil Biology at the Faculty of Soil Science of Moscow State University into one of the major functions of soil microorganisms—sustenance of the turnover of matter and energy in the biosphere—are discussed. Data on the population densities of soil microbes and on the microbial biomass in different types of soils are presented. The systemic approach has been applied to study the structural-functional organization of the soil microbial communities. The role of eukaryotic and prokaryotic microorganisms in the carbon and nitrogen cycles is elucidated. It is argued that the high population density and diversity of microorganisms are necessary to maintain the turnover of chemical elements in terrestrial ecosystems. The viability of microbes stored in the soils is important. New data on the preservation and survival of bacteria in nanoforms are presented. It is shown that peatlands and paleosols are natural banks, where microbes can be preserved in a viable state for tens of thousands years.

Mycological Characteristics of the Cultural Layer of a Medieval Settlement on Soddy Calcareous Soils

The difference between fungal communities in the cultural layer of a medieval settlement and in the background soddy calcareous soil is shown. In the cultural layer, the portion of spores, especially large spores (d > 6 μm), in the total fungal biomass is increased, whereas the portion of mycelium, especially with a thickness of > 4 μm, is decreased. The species composition of micromycetes in the cultural layer is also transformed; species from the Aspergillus and Fusarium genera predominate. The frequency and diversity of Penicillium representatives decreases, whereas the fungal species from the Phoma, Doratomyces, Geomyces, and Verticillium genera, which are not typical of the background soil horizons, increases. The diversity of the minor fungal species also increases in the cultural layer. An increased content of keratin-decomposing soil fungi is found in the cultural layer. It is argued that the use of the entire set of these characteristics makes it possible to perform mycological indication of the parts of the cultural layer that served different purposes (ancient streets, house floors, backing of the walls, etc.) within the settlement.

The Distribution of Microscopic Fungi along Moscow Roads

The distribution of microscopic fungi in soils and surface air along some Moscow roads was studied from 1994 through 2000 at several distances (0, 5, 10, and 20 m) from the roads. Soil fungal complexes in roadside zones with different levels of pollution from automobile engines were found to differ in their composition, species structure, and biomorphology. Relatively far from the roads, the content of fungal mycelium diminished, while that of fungal spores increased. Close to the roads, fungal complexes in soil and surface air were dominated by dark melanin-containing fungi. The microscopic fungal complexes of soil and surface air along the roadsides were similar but differed in the relative abundance of some species.

Mycological characterization of the occupation deposits in excavated medieval Russian settlements

Microbiological analysis showed that the cultural layers of soils in excavated medieval Russian settlements differ from the surrounding soils in that the cultural layers have more fungal spores, their morphology is more diverse, the species diversity of microscopic fungi is higher, and the Penicilliumspecies that are able to grow at an elevated temperature (37°C) are more frequent.

[Comparative morphological, ecological, and molecular studies of Aspergillus versicolor (Vuill.) Tiraboschi strains isolated from different ecotopes].

Cultural, morphological, ecological, and trophic properties (growth at different temperatures and on various organic substrates), as well as molecular and genetic peculiarities of Aspergillus versicolor (Vuill.) Tiraboschi strains of different origins, were determined. The strains were isolated from different ecotopes (upper horizons of modern soils of several geographic regions, ancient soils and peat, and permafrost). No essential distinctions in cultural and morphological properties were revealed between the strains. Strains obtained from peat of the Aleutian Islands were characterized by the highest radial rates of colony growth. Some variations in the ITS loci of rDNA were observed in strains isolated from different ecotopes; the distinctions were most pronounced (1.7%) in the strain isolated from 100 000-year-old permafrost.

Fungal communities in the soils of early medieval settlements in the taiga zone

The difference between the mycobiota in anthropogenically transformed soils of the settlements of the 9th–14th centuries and in the background zonal Podzols and umbric Albeluvisols of the middle and southern taiga subzones in the European part of Russia is demonstrated. The mycological specificity of anthropogenically transformed soils with a cultural layer (CL) in comparison with the background soils is similar for all the studied objects. Its characteristic features are as follows: (1) the redistribution of the fungal biomass in the profile of anthropogenically transformed soils in comparison with zonal soils, (2) the lower amount of fungal mycelium in the CL with the accumulation of fungal spores in this layer, (3) the increased species diversity of fungal communities in the CL manifested by the greater morphological diversity of the spore pool and by the greater diversity of the fungi grown on nutrient media, (4) the change in the composition and species structure of fungal communities in the CL, (5) the replacement of dominant species typical of the zonal soils by eurytopic species, and (6) the significant difference between the fungal communities in the CL and in the above-and lower-lying horizons and buried soils of the same age. Most of the mycological properties of the soils of ancient settlements are also typical of modern urban soils. Thus, the mycological properties of soils can be considered informative carriers of soil memory about ancient anthropogenic impacts.

The structure of fungal biomass and diversity of cultivated micromycetes in Antarctic soils (progress and Russkaya Stations)

The distribution of the fungal biomass and diversity of cultivated microscopic fungi in the profiles of some soils from East (Progress Station, valleys of the Larsemann Hills oasis) and West (Russkaya Station, the Marie Byrd Land) Antarctica regions were studied. The structure of the biomass (spore/mycelium and live cells/dead cells) was analyzed by fluorescence microscopy with staining using a set of coloring agents: calcofluor white, ethidium bromide, and fluorescein diacetate. The species composition of the cultivated microscopic fungi was determined on Czapek’s medium. The fungal biomass in the soils studied is not high (on the average, 0.3 mg/g of soil); the greatest biomass (0.6 mg/g) was found in the soil samples with plant residues. The fungal biomass is mainly (to 70%) represented by small (to 2.5 μm) spores. About half of the fungal biomass is composed of living cells. There are differences in the distribution of the fungal biomass within the profiles of different primitive soils. In the soil samples taken under mosses and lichens, the maximal biomass was registered in the top soil horizons. In the soils with the peat horizon under stone pavements, the greatest fungal biomass was registered in the subsurface horizons. Thirty-eight species of cultivated microscopic fungi were isolated from the soils studied. Species of the genus Penicillium and Phoma herbarum predominated.

Fifty years of mycological studies at the White Sea Biological Station of Moscow State University: Challenges, results, and outlook

This review covers the history of the mycological studies performed at Pertsov White Sea Biological Station, Moscow State University (WSBS MSU). The WSBS was established more than 70 years ago; presently, it is one of the main divisions of the university, where numerous educational and research marine programs are fulfilled. Mycological studies have been performed here for more than half a century, focusing on biodiversity and ecology of marine, littoral, and soil fungi and fungi-like protists. Various research projects resulted as a number of scientific publications, diploma (MSc) theses, and dissertations. Presently, WSBS MSU and its vicinity is the northernmost area researching the best in regard to mycobiota. However, a number of blind spots still exist; thus, the future studies in this region should focus on diversity and biology of epiphyte fungi, ecology of fungi and fungi-like protists, and on fungi phylogeny.

Mycological complexes in Holocene and Late Pleistocene paleohorizons and in fragments of paleosols.

Fragments of buried Late Pleistocene (30000-year-old) and Early Holocene (10000-year-old) paleosols contained viable complexes of microscopic fungi. The mycobiota of these paleosols represents a pool of fungal spores that is lower in number and species diversity as compared to that in the recent humus horizons and higher than that in the inclosing layers. The central part of the paleosol profiles is greatly enriched in microscopic fungi. In the intact humus horizons of the Late Holocene (1000–1200 years) paleosols, actively functioning fungal complexes are present. These horizons are characterized by their higher level of CO2 emission. The buried horizons, as compared to the recent mineral ones, contain a greater fungal biomass (by several times) and have a higher species diversity of microscopic fungi (including fungi that are not isolated from the recent horizons). Nonsporulating forms are also present there as sterile mycelium. The seasonal dynamics of the species composition and biomass of the fungal complexes were more prominent and differed from those inherent to the surface soil horizons. In the buried humus horizons, the dynamics of the fungal biomass were mainly due to the changes in the content of spores. The data on the composition of the fungal complexes in the buried soils confirm (due to the presence of stenotopic species) the results of paleobotanic analyses of the past phytocenoses or do not contradict them.

Secondary mobilization of heavy metals in polluted soils under microbial influence (model experiment)

Publisher Summary This chapter examines the role of soil microbial community in heavy metals mobility change in background and strongly polluted podzols of the Kola Peninsula. It was shown in the study discussed in the chapter that microbiological activity in polluted soils leads to copper mobilization, mostly because of organic matter decomposition and release of copper bound to it. Two common soil microfungi— Mucor hiemalis Wehmer and Trichoderma viride Pers. ex Gray—were shown to be able to modify copper availability in soil. Copper mobilization under their influence occurs in different time intervals corresponding to their growth rates. The difference in copper availability dynamics in natural and sterilized soil samples demonstrates the possible effect of microbiota on heavy metals availability in soil. The activity of the soil microbial community may lead to increases or decreases of heavy metals mobility, depending on the metal, its concentration in soil solution, and the stage of microbial succession development. In the polluted soil, microbiological activity leads to the increase of availability of metals that are present in soil solution in high concentrations.