bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of the Component Interaction on the Phase Transitions and Dielectric Properties of Ferroelectric Composites
Authors: Sidorkin A. S. , Darinskii B. M. , Milovidova S. D. , Korotkov L. N. , Grigoryan G. S.
Published: April 2024

The dielectric properties of ferroelectric composites and the specific features of the phase transitions occurring in them are discussed in comparison with the homogeneous ferroelectrics incorporated in the composites studied. The components incorporated into the dielectric matrix of ferroelectrics are considered to be triglycine sulfate, single crystals of potassium dihydrogen phosphate group, sodium nitrite, and perovskite-type materials. The factors changing the temperature range of polar phase existence in the ferroelectric composites under consideration are revealed and discussed. The results of the studies performed in this field are briefly reviewed. The work with the ferroelectric components incorporated into the aforementioned composites was performed in cooperation and under the guidance of L.A. Shuvalov.
Low-Frequency Internal Friction in Crystals of the Potassium Dihydrogen Phosphate Family
Authors: Gridnev S. A.
Published: April 2024

The low-frequency internal friction Q–1 and shear modulus G have been studied by the inverted torsion pendulum method for a series of crystals belonging to potassium dihydrogen phosphate family: KH2PO4, KD2PO4, 0.95KH2PO4–0.05NH4H2PO4, RbH2PO4, RbH2AsO4, and CsH2AsO4. A number of anomalies have been revealed in the temperature dependences Q–1(T) and G(T), both in the ferroelectric and paraelectric phases of these crystals; the nature of these anomalies is discussed.
Relaxor Ferroelectric PbNi1/3Ta2/3O3: Synthesis, Structure, Raman Spectra, and Dielectric Susceptibility
Authors: Levin A. A. , Smirnova T. A. , Obozova E. D. , Zalesskii V. G. , Fedoseev A. I. , Lushnikov S. G.
Published: April 2024

The structure of the relaxor ferroelectrics PbNi1/3Ta2/3O3 (PNT) was studied by powder X-ray diffraction. The measurements were performed at 313.5 ± 1 K using a powder, which was prepared by grinding PNT single crystals grown by the spontaneous crystallization. The structure refinement and the fitting of the simulated diffraction pattern to the experimental data were performed by the Rietveld method. It was demonstrated that the grown crystals of PNT have a perovskite structure (sp. gr. Pm3m (221), a = 4.02679(2) Å). Polarized Raman spectra of PNT were recorded at room temperature. The main modes of the light scattering spectra were assigned to the Е1 and А1 components of the transverse optical phonon (ТО1) and the А1 component of the longitudinal optical phonon (LO3). The temperature dependence of the dielectric susceptibility shows a broad frequency-dependent anomaly with a maximum at 89 К at a frequency of 1 kHz.
Breaking of the Cubic Symmetry in Millimeter-Size SrTiO3 Crystals: ESR Manifestations
Authors: Gabbasov B. F. , Gracheva I. N. , Nikitin S. I. , Trepakov V. A. , Yusupov R. V.
Published: April 2024

The found effect of lowering the symmetry of the crystal structure of thin (less than 1 mm) plates and bars of strontium titanate (SrTiO3) single crystals is discussed. This symmetry lowering manifests itself in the electron spin resonance (ESR) spectra of impurity centers (Fe3+and Mn4+ions, used as paramagnetic probes). It is shown that symmetry lowering is observed at temperaturesT 105 K, which generally correspond to the cubic phase of SrTiO3; it leads to the formation of a tetragonal nonpolar structure, differing from the antiferrodistortive (AFD) phaseD4ℎ18, which is characteristic of strontium titanate atT 105 K and was not observed previously in SrTiO3. The factors determining the distortion value are found to be the geometry and ratio of sample sizes, surface finishing quality, and crystallographic orientation of plates.
Dielectric Relaxation in a Nanosize Ferroelectric with an Incommensurate Phase Rb2ZnCl4
Authors: Korotkov L. N. , Stekleneva L. S. , Pankova M. A. , Bocharov A. I. , Rysiakiewicz-Pasek E.
Published: April 2024

The dielectric properties of a composite obtained by embedding a ferroelectric salt Rb2ZnCl4 into a porous glass matrix with an average size of through pores of about 46 nm have been studied within the temperature range of 100–350 K at frequencies of 5–500 kHz. An increase in the dielectric permittivity dispersion depth Δε upon sample cooling, due to an increase in the concentration of “relaxers” and an increase in their dipole moment, was found. An analysis of the dielectric response features showed that a domain structure is formed in the ferroelectric phase of Rb2ZnCl4 particles, the mobility of which in the vicinity of the freezing temperature Tf obeys the empirical Vogel–Fulcher relation
Growth of Ferroelectric Domains in Polar Direction
Authors: Shur V. Ya. , Pelegova E. V. , Turygin A. P. , Kosobokov M. S. , Alikin Yu. M.
Published: April 2024

The forward domain growth in polar direction has been investigated on the example of the formation of isolated wedge-shaped domains and arrays of domains on lithium niobate nonpolar cuts under an electric field of a scanning probe microscope. Domain growth occurs due to the generation of steps and motion of charged kinks along charged domain walls (CDWs). A simulation of field spatial distribution showed that the generation of steps near a domain vertex is mainly caused by the effect of external field, whereas the forward growth is due to the kink motion in the field induced by neighboring kinks. Scanning by a probe tip with an applied voltage leads to the self-assembled formation of domain arrays with domain length alternation: doubling, quadrupling, and chaotic behavior under the action of the depolarizing fields formed by three neighboring domains.
Study of the Precrystallization Solution of Lysozyme by Accelerated Molecular Dynamics Simulation
Authors: Ivanovsky A. S. , Garipov I. F. , Kordonskaya Yu. V. , Timofeev V. I. , Marchenkova M. A. , Pisarevsky Yu. V. , Dyakova Yu. A. , Kovalchuk M. V.
Published: April 2024

The behavior of a dimer isolated from the crystal structure of tetragonal lysozyme has been simulated using the accelerated molecular dynamics method. The simulation time was 240 ns. The simulation data are compared with the data obtained previously using classical molecular dynamics. It is shown that the dimer studied is stable in both experiments, but the accelerated molecular dynamics method made it possible to reveal additional conformational changes in lysozyme molecules.
Ab Initio Shape of Supramolecular Complexes of Cucurbit[8]uril in Solution Found from Small-Angle X-ray Scattering Data
Authors: Volkov V. V. , Livshits V. A. , Meshkov B. B. , Asadchikov V. E.
Published: April 2024

Previous studies of the spatial structure of the guest–host complexes of macrocyclic cavitands cucurbiturils with a number of nitroxyl radicals by ESR, NMR, and crystallographic methods showed that, in aqueous solutions containing a number of nitroxyl radicals as guest molecules, ordered aggregates in the form of an equilateral triangle, with three guest–host monocomplexes located in its vertices, may arise. We performed experiments on small-angle X-ray scattering of aqueous solutions of guest–host cucurbit[8]uril complexes with a stable nitroxyl radical (protonated tempoamine) and, based on the experimental results, carried out ab initio modeling of the shape of aggregates of complexes in the natural state in solution. The search for models of the shape of aggregates was performed either using no additional information about their structure or assuming the presence of a threefold axis. ESR is applied as an independent method for studying the aggregation of complexes in solution. It is shown that the shape of the particles constituting complexes at high cavitand and guest concentrations in an aqueous solution is close in its parameters to an equilateral triangle, which is in agreement with the known crystallographic and ESR data.
3D Structure of D-Аmino Acid Тransaminase from Aminobacterium colombiense in Complex with D-Cycloserine
Authors: Shilova S. A. , Matyuta I. O. , Bezsudnova E. Yu. , Minyaev M. E. , Nikolaeva A. Yu. , Popov V. O. , Boyko K. M.
Published: April 2024

D-cycloserine inhibits pyridoxal 5'-phosphate (PLP)-dependent enzymes both reversibly and irreversibly. As an alanine racemase inhibitor, D-cycloserine is used in drug therapy in the treatment of tuberculosis. Several products of the interaction of D-cycloserine and PLP in the active site of the enzyme are known. The crystal structure of the complex of PLP-dependent D-amino acid transaminase from the bacteria Aminobacterium colombiense (Amico) with D-cycloserine obtained at a resolution of 1.9 Å is presented, in which the ring-opened adduct of PLP and D-cycloserine was discovered. In addition, the interaction of D-cycloserine with Amico has been characterized by the kinetic and spectral methods, various products of the interaction of D-cycloserine and PLP in the active site of transaminase have been determined, and the coordination of D-cycloserine and PLP adducts in the Amico active site has been analyzed. It is established that the products of the interaction of D-cycloserine with PLP in the Amico active site are several compounds, including PLP and DCS adducts in the cyclic and open forms, oxime formed by PMP and β-aminooxy-D-alanine, and PMP and β-aminooxypyruvate.
Improvement of the Diffraction Properties of Thiocyanate Dehydrogenase Crystals
Authors: Varfolomeeva L. A. , Polyakov K. M. , Komolov A. S. , Rakitina T. V. , Dergousova N. I. , Dorovatovskii P. V. , Boyko K. M. , Tikhonova T. V. , Popov V. O.
Published: April 2024

During determination of the thiocyanate dehydrogenase (TcDH) structure difficulties have occurred, related to the fact that enzyme crystals have been either twinned or strongly anisotropic. The diffraction quality of crystals can be improved by using mutant forms as objects of a study or by studying the structure of a related enzyme from another organism. Based on the analysis of the oligomeric structure of TcDH, the mutant forms of the enzyme that are promising for improving the diffraction properties have been proposed. The crystals have been obtained and the structures of the TcDH mutant forms with the substitutions T169A and K281A have been solved. The structure of the mutant form with the substitution T169A is found to be similar to the previously solved structures. In the structure of the mutant form with the substitution K281A, a change in the tetramer structure that made twinning impossible has been detected.
Electron Microscopy Study of the Structure of the Sup35 Prion from Yeast Saccharomyces cerevisiae
Authors: Burtseva A. D. , Moiseenko A. V. , Baymukhametov T. N. , Dergalev A. A. , Boyko K. M. , Kushnirov V. V.
Published: April 2024

Prions form an infectious version of amyloid; they are involved in the pathogenesis of some human neurodegenerative diseases, including Alzheimer’s and Parkinson’s diseases. Yeast prions, in particular, the Sup35 protein, serve an effective model for studying the basic properties of amyloids. Strain versions of the prion form of Sup35 lie in the basis of the conformational diversity of the amyloid structures formed by it, which exhibit different biological properties. The spatial organization of the Sup35 prion has not yet been established. The structure of the strain version W of Sup35 prion protein, isolated ex vivo from yeast Saccharomyces cerevisiae, was studied by transmission electron microscopy (TEM). The parameters of the fibril were estimated, and its structure was reconstructed with a low resolution.
MÖSSBAUER SPECTROSCOPY OF FUNCTIONAL MECHANOCOMPOSITES
Authors: Kiseleva T. Yu. , Novakova A. A. , Grigoreva T. F. , Lyakhov N. Z.
Published: April 2024

The results of the Mössbauer spectroscopy studies in the field of mechanochemical synthesis of functional composites, carried out for more than 25 years at Lomonosov Moscow State University (Faculty of Physics, Department of Solid State Physics) and at the Institute of Solid-State Chemistry and Mechanochemistry of the Siberian Branch of the Russian Academy of Sciences (Laboratory of Chemical Materials Science), are reviewed.
X-RAY DIFFRACTION STUDIES OF THE EFFECT OF PHASE COMPOSITION AND STRUCTURAL STATE CHARACTERISTICS ON THE TRIBOLOGICAL BEHAVIOR OF THE MOLYBDENUM- AND TUNGSTEN-BASED STRENGTHENING COATINGS
Authors: Avdyukhina V. M. , Khrushchov M. M. , Sulyandziga D. A. , Levin I. S.
Published: April 2024

A comprehensive study of phase composition, structural state, parameters of fine atomic structure, mechanical and tribological properties of molybdenum-carbon and tungsten-carbon-based coatings deposited by reactive magnetron sputtering in an acetylene-argon gas mixture has been carried out. It has been shown that the resulting coatings have a nanocomposite diamond-like carbon (DLC) structure based on the metal and the metal carbide phases with close sizes of coherently diffracting domains (CDD), approximately 3–7 nm, and on hydrogenated amorphous carbon. The coating nanohardness values were 13–15 and 20–23 GPa for the Mo-DLC and W-DLC coatings, respectively. The tribological tests have demonstrated that the Mo- and W-DLC coatings can reduce friction and effectively protect the steel surfaces hardened by them both under dry friction and under boundary lubrication conditions.
MICROSTRUCTURE OF GEL FILMS OF BACTERIAL CELLULOSE SYNTHESIZED UNDER STATIC CONDITIONS OF CULTIVATION OF THE GLUCONACETOBACTER HANSENII GH-1/2008 STRAIN ON NUTRIENT MEDIA WITH DIFFERENT CARBON SOURCES
Authors: Bolgova A. L. , Shevtsov A. A. , Arkharova N. A. , Karimov D. N. , Makarov I. S. , Gromovykh T. I. , Klechkovskaya V. V.
Published: April 2024

The study presents a comparative analysis of the structures of dried films of bacterial cellulose (BC) produced by bacteria of the Gluconacetobacter hansenii GH-1/2008 strain under static conditions of cultivation on nutrient media with different carbon sources, such as glucose, sucrose, maltose, fructose, and lactose. It was found that the supramolecular structure of the films is a three-dimensional network composed of orientationally ordered microfibrils with an average diameter from 30 to 60 nm, which consist of crystalline and amorphous regions. An analysis of the powder X-ray diffraction patterns demonstrated that the crystalline regions of microfibrils are formed by cellulose I. Depending on the composition of the nutrient medium, the degree of crystallinity of the films varies in the range from ~20 to 90%. It was found that, regardless of the carbon source, the top and bottom surfaces of BC films have different microstructures defined by static conditions of cultivation. Thus, the top surface of gel films contains pores with a diameter of up to 500 nm, whereas a wider pore size distribution (up to 600 nm) is observed on the bottom surface. The difference between the average pore sizes on the top and bottom surfaces varies from 95 to 180 nm and from 100 to 200 nm, respectively. The measurements of the mechanical properties of the films showed that the films produced by the cultivation on media containing fructose and sucrose have the maximum strength, whereas the films produced using lactose and maltose have the minimum strength. The data on the BC productivity of the GH-1/2008 strain were obtained.
The Structure of the Hfq Protein from Chromobacterium haemolyticum Revealed a New Variant of Regulation of RNA Binding with the Protein
Authors: Lekontseva N. V. , Nikulin A. D.
Published: April 2024

The structure of the Hfq protein from the bacterium Chromobacterium haemolyticum, which forms crystals in two different spatial groups, has been determined. In both cases, the protein has a specific quaternary hexamer-ring structure. The obtained structure showed a previously undescribed interaction between the C-terminal unstructured part of Hfq and the amino acid residues of the proximal RNA-binding site of the protein. This contact may contribute to the regulation of the binding of RNA molecules to the Hfq protein.
Lithological Composition and Hydrocarbon Anomalies of Bottom Sediments of the Western Part of the East Siberian Sea
Authors: Gresov A. I. , Yatsuk A. V. , Aksentov K. I.
Published: April 2024

On the basis of lithological and gas geochemical studies and a comprehensive interpretation of the available materials, the main factors of the formation and distribution of grain size distribution, water-physical properties, organic saturation, concentrations and geochemical parameters of hydrocarbon gases in seafloor sediments of geostructures of the western part of the East Siberian Sea are summarized and analyzed. It has been established that the sediments of the northern and central parts of the study area are represented by aleurite-pelites, the southern ‒ by aleurite-pelite-psamites with variations in Corg values ‒ 0.6–2.0%, natural humidity and density ‒ 18–43% and 1.5–2.0 g/cm3, open porosity ‒ 17–33%, the concentrations of methane and its homologues are 0.001–5.934 and 0.00003–0.0312 cm3/kg, the molecular mass of the hydrocarbons fraction, the “wetness”, “dryness” coefficients, and the coefficients of the transformation are 16.05–22.6 g/mol, 0.2–51%, 1–1999, 0.2–50.8 and δ13С‒СН4 (–82.7…–38.4‰). Based on the values of gas geochemical parameters, eleven types of gas sources were identified in bottom sediments. In the process of research, it was found that the formation of hydrocarbon anomalies in sediments is mainly associated with their reservoir properties, Corg content and depths of their sampling, as well as with the complex influence of geological factors, the main of which are the gas saturation of the underlying sediments and the type of gas sources, discontinuous and plicative tectonics, geostructures position, thickness of Quaternary deposits, coal and gas content and age of the folded base. To a lesser extent, anomalies of hydrocarbon gases are associated with the lithological composition and density parameters of sediments.
Lidites of the North Onegian Synclinorium of Karelia, Their Trace Element Composition and Possible Genesis
Authors: Kondrashova N. I. , Medvedev P. V.
Published: April 2024

We studied of Paleoproterozoic siliceous rocks (lidites) geochemistry from the North-Onegian synclinorium (Karelia). The objects of research are represented by 16 samples of lidites selected from one stratigraphic level in geological sections of two sites – Tetyugino and Shunga. Their structural characteristics and mineral composition features were studied using a scanning electron microscope with an energy-dispersion microanalyzer. The trace elements were determined by the inductively coupled plasma mass spectrometric method (ICP MS). Tetyugino lidites contain biophilic elements (P, Co, Cu, Mo, V, Ba) predominantly, while Shunga lidites ‒ lithophilic elements (Li, Rb, Cs). The trace element composition of lidites indicates that their formation took place on the periphery of the hydrothermal system, while the Tetyugino site was closer to the place of hydrothermal discharge than Shunga. The peculiarities of the lidites chemical composition allow us to consider them as raw materials for very pure quartz.
Post-Sedimentation Transformations in Silurian Carbonate Rocks of the Central Part of the Chernyshev Ridge (Timan-Pechora Province)
Authors: Danshikova I. I. , Maydl T. V.
Published: April 2024

The article presents the results of studies of post-sedimentary processes in Silurian carbonate rocks of the central part of the Chernyshev Ridge. A complex combination of secondary transformations in carbonate re-servoir is shown. The sedimentary strata show manifestations of regional and superimposed lithogenesis. In addition to stage-catagenetic changes, the sediments were also exposed to regressive infiltration catagenesis (epigenesis), accompanied by leaching and dolomitization of limestone. All this significantly affected the filtration-capacitative properties. The obtained data can contribute to the identification of new objects for exploration drilling and optimization of exploration works in the complex territories.
Granulometric Composition of Neopleistocene Basal Morains in the Far Northeast of the Russian Plain
Authors: Andreicheva L. N.
Published: April 2024

The results of granulometric analyzes of the basal Neopleistocene moraines from sections of coastal outcrops and boreholes in the vast territory of the European Subarctic of Russia and in the more southern regions of the Timan-Pechora-Vychegoda region have been summarized. It showed that moraines are typical mixed, practically unsorted rocks with similar contents of gravel-sand, silt, and clay fractions, which is one of arguments is in favor of thear glacial genesis. Their granulometric composition is due to the peculiarities of the rocks of the ice bed.It is formed in the process of crushing, abrasion, and mixing of material assimilated and transported by the glacier during its transportation and deposition, which determines the variability of the granulometric composition of moraines. As a result, the granulometric composition of the moraines in combination with other lithological data reflects the path of the glacier and the dynamics of its movement.
Features of Using the Lithogeochemical Indicators for the Reconstruction of Paleoclimate and Composition of Demolition Sources in the Late Jurassic-Lower Cretaceous West Siberian Sedimentary Basin
Authors: Eder V. G. , Zamiralova A. G. , Yan P. A.
Published: April 2024

For the rocks of the Upper Jurassic-Lower Cretaceous Bazhenov formation, a significant positive linear dependence of the Th, Hf, Sc, La content on the Al2O3 content was revealed, and their terrigenous genesis was confirmed. It has been determined that the samples in which the distribution of the values of the Sc/Al2O3 and La/Al2O3 ratios does not satisfy the linear dependence are mixed clayey-siliceous rocks with a P2O5 content 1 mas. % or substantially pyritized (in which the content of pyrite exceeds the content of S and C/S ≤ 1), as well as siliceous mudstones with a SiO2 content 70 mas. % by weight. It is concluded that before analyzing geochemical indicators for reconstructing the conditions of formation of the Bazhenov formation, in addition to carbonated rocks, rocks of the above types, as well as rocks that have undergone late diagenetic kaolinization, should be excluded from the analysis. The conditions of formation of the studied deposits were reconstructed based on the analysis of the values of a number of geochemical modules and indicators. As a result of the study of CIA, CIW variations, it was confirmed that the climate in the Late Jurassic-Early Cretaceous period in the West Siberian sedimentary basin was warm, semiarid. It was revealed that during the entire period under review, it did not change significantly. For the deposits of the Bazhenov formation, a number of indicators such as (La/Yb)N, Eu/Eu*, as well as the distribution of trace element content values on the triangular diagram Th‒La‒Sc, suggest that in the central and southeastern regions of the formation distribution area, the sources of demolition of the mafic composition prevailed.
Sorption Properties of Cobalt-Rich Ferromanganese Crusts of the Kotzebue Guyot of the Magellanic Mountains Relative to Cations of Rare Earth Metals
Authors: Novikov G. V. , Lobus N. V. , Bogdanova O. Y.
Published: April 2024

The article presents the results of experimental studies of the sorption properties of ferromanganese crusts (CMC) of Kotzebue guyot relative to rare earth metal cations (REM). It is established that the crusts are a natural highly selective sorbent of REM cations. The sorption of REM cations occurs on ore minerals ‒ Fe-vernadite, vernadite, Mn-feroxigite, goethite. The crusts are characterized by a high exchange capacity – 1.67‒3.28 mg-eq/g, which increases in the series: Lu Gd Dy La, Sm Nd Y Eu) ⪡ Ce. Absorption of REM cations proceeds by an ion-exchange equivalent mechanism, in the case of Ce3+ cations ‒ according to the superequivalent mechanism with respect to the cations of the exchange complex of ore minerals ‒ Na+, K+, Ca2+, Mg2+, Mn2+, Ni2+, which contribute 95–98% to the total capacity of minerals.
Fungal Azaphilone Pigments as Promising Natural Colorants
Authors: Antipova T. V. , Zhelifonova V. P. , Zaitsev K. V. , Vainshtein M. B.
Published: April 2024

Abstract—Microscopic fungi form and excrete numerous and diverse secondary metabolites, including pigments of various colors, which may be used as an alternative to chemical and plant colorants used in industry. Azaphilone compounds, first discovered in fungi of the genus Monascus, are among the promising classes of fungal pigments. The review analyzes the publications on formation of azaphilone-type pigments in Monascus fungi, as well as in Talaromyces and Aspergillus сavernicola. Brief information is provided concerning the antimicrobial, antitumor, anti-inflammatory, and hypolipidemic activities of azaphilone pigments. is given. Possible strategies for increasing the efficiency of the production process and directed synthesis of yellow, orange, and red pigments and their derivatives are discussed. In general, the review provides for assessment of the role of azaphilone pigments, as well as of the prospects and ways to expand their production for use as natural dyes in various fields.
Biodegradation Patterns of Composite Materials Based on High-Density Polyethylene and Starch
Authors: Suslova T. N. , Salakhov I. I. , Nikonorova V. N. , Gilaeva G. V. , Trifonova O. M.
Published: April 2024

Abstract—The degradation properties of high-density polyethylene composites filled with amylose and amylopectin polysaccharides were studied. At low dosages of the polysaccharides (0.5% wt/wt), no change in viscosity, molecular weight and physical and mechanical characteristics of HDPE samples were observed, while an increase in the proportion of the natural filler (starch) to 1 and 5% resulted in a decrease in mechanical properties, although the values of deformation and strength parameters satisfied the minimum necessary requirements for film packaging. After incubation in soil for one year, the sample of HDPE film with a corn starch content of 5% (wt/wt) was found to undergo the greatest changes in its properties. The study of ability of aerobic microorganisms to carry out the surface transformation of the studied film composites revealed that bacteria of the genus Bacillus efficiently colonized the polyethylene-starch composites. Among the identified microorganisms, micromycetes of the genus Penicillium and Trichoderma caused the most pronounced changes in the structure of the studied polymer composites, and the greatest effect was achieved in the case of synergistic action of different micromycetes genera.
Leucosporidium egoroviorum f.a., sp. nov., a New Yeast Species Isolated from Zucchini
Authors: Kachalkin A. V. , Glushakova A. M. , Tomashevskaya M. A.
Published: April 2024

Abstract—Leucosporidium egoroviorum f.a., sp. nov., a new anamorphic species of the basidiomycetous yeasts, was isolated as an endophyte from the fruits of Cucurbita pepo subsp. pepo (zucchini). According to its genetic, physiological, and morphological characteristics, the new species differed significantly from the closely related species L. fellii, L. intermedium, and L. krtinense. The holotype of the new specise, KBP Y-6804T, is preserved in a metabolically inactive state; its isotype strains are VKM Y-3065, DSM 113574, and CBS 17590. The MycoBank number is MB 842805.
Structure and Seasonal Variability of Groundwater Microbial Communities in the City of Moscow
Authors: Gruzdev E. V. , Begmatov Sh. A. , Beletsky A. V. , Mardanov A. V. , Ravin N. V. , Kadnikov V. V.
Published: April 2024

Abstract—Groundwater, which appears on the surface in the form of springs, is an important ecologically significant component of the aquatic ecosystem, sensitive to changes in environmental conditions. The anthropogenic impact associated with urbanization leads to a change in the characteristics of groundwater, which in turn affects the composition of microbial communities in spring waters. Using high-throughput sequencing of the 16S ribosomal RNA gene fragments, we characterized the composition of microbial communities in five natural springs in the city of Moscow in the spring, summer, and winter seasons. The microbial communities of each spring in different seasons were similar to each other and clearly differed from the microbiomes of other springs. Among the Archaea, which averaged about 20% of microbial communities, ammonium-oxidizing Crenarchaeota predominated, as well as Nanoarchaeota. Most of the Bacteria belonged to the phyla Proteobacteria, Patescibacteria, Verrucomicrobiota, Chloroflexi, and Bacteroidota. Autotrophic bacteria, including iron-oxidizing bacteria of the family Gallionellaceae and nitrifiers, as well as methanotrophs, accounted for significant proportions in microbial communities in the springs with a presumably deeper water source. Chemical and molecular analyzes did not reveal contamination of spring waters with toxic substances and oil-derived products, as well as the presence of pathogenic microorganisms and indicators of fecal pollution. However, during the spring season, the proportions of halophilic and hydrocarbon-oxidizing bacteria increased in water microbiomes, which may reflect entry into groundwater after snow thawing of deicin reagents and hydrocarbons, which are successfully biodegraded in the soil.
Rhodococcus rhodochrous IEGM 1360, an Efficient Biocatalyst of C3 Oxidative Transformation of Oleanane Triterpenoids
Authors: Luchnikova N. A. , Tarasova E. V. , Grishko V. V. , Ivshina I. B.
Published: April 2024

Abstract—The optimal conditions for C3 oxidative biotransformation of 1.0 g/L pentacyclic triterpenoids oleanolic (OA) and glycyrrhetic (GA) acids were determined using the resting cells of Rhodococcus rhodochrous IEGM 1360 from the Regional Specialised Collection of Alkanotrophic Microorganisms. Suspensions of the resting cells with OD600 2.6 in pH 8.0 buffer and OD600 2.2 in pH 6.0 buffer showed the highest catalytic activity against OA and GA, which ensured the formation of 61 and 100% of their 3-oxo derivatives, respectively. Using phase contrast, atomic force, and confocal laser scanning microscopy, an adaptive response of rhodococci to the effects of OA and GA was revealed. In silico, the apoptotic and antioxidant activities of 3-oxo-OA and 3-oxo-GA, respectively, have been assumed. In vitro, a pronounced antibacterial activity of 3-oxo-OA against Micrococcus luteus, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis was shown. The absence of toxic effects of the triterpenoids and their 3-oxo derivatives on aquatic and plant objects was demonstrated in silico and in vitro, respectively.
Adaptive Properties of Arthrobacter agilis Strain wb28 Isolated from Wheat Bran
Authors: Sharova N. Yu. , Prichepa A. O. , Sverdlova O. P. , Printseva A. A.
Published: April 2024

Abstract—The article presents the results of a study of some adaptive properties of a bacterial isolate from wheat bran, identified by the 16S rRNA gene as an Arthrobacter agilis strain. According to the literature data, A. agilis does not belong to the dominant bacterial species of wheat microbial associations and activates growth at low ambient temperatures. The studied A. agilis strain showed poor growth in a microbial consortium when an aqueous suspension of wheat bran, partially fermented at 28 ± 1°C by the native microbiota, was plated on a dense MPA medium and produced the pigment after three weeks of storage at 4 ± 1°C. Moderate growth of bacteria without increased pigmentation was observed during its subsequent transfer after low-temperature storage on agar media containing carbohydrates and nitrogen compounds, mineral salts, and vitamins that were more easily utilized than native bran. The growth of colonies upon plating on such media increased in the series: thermally fermented wheat bran → HMF agar → LB (without salt). It was revealed that the A. agilis strain, which was not typical of the wheat bran microflora, under the influence of osmotic and/or temperature shock (in response to a sharp change in the NaCl concentration and/or a difference in ambient temperatures) produced pigments both in agar and liquid cultures. According to the results of spectral analysis, the pigment was assigned to carotenoids and tentatively identified as bacterioruberin. Quantitative evaluation showed that, under stress conditions during submerged cultivation, the studied strain A. agilis wb28 was able to synthesize the pigment at the level of 52.8 mg/L (17.2 mg/g biomass).
Diurnal Methane Dynamics in the Cyanobacterial Community of Soda Lake Bitter 1 (Kulunda Steppe, Altai Krai)
Authors: Samylina O. S. , Merkel A. Yu. , Pimenov N. V.
Published: April 2024

Abstract—The diurnal dynamics of methane content in the near-bottom phototrophic biomass of the shallow soda Lake Bitter 1 (Gorchina 1) with a salinity of 30 g/L during the study period was investigated. The community was dominated by filamentous cyanobacteria, although no layered mat was formed. The maximum value of methane content up to 202.4 nmol CH4/cm3 was revealed in the morning hours, which significantly exceeded the night values (28.9–42.8 nmol CH4/cm3). Comparison of data on the content of methane with the relative abundance of cyanobacteria, methanogenic archaea, and methanotrophic bacteria during the twenty-four hours indicated that active processes of the methane cycle in soda lakes occurred not only in the sediments, but also in the near-bottom cyanobacterial communities. Methane content in the biomass of such a community is the result of a balance between the processes of its release by methanogens, consumption by methanotrophic bacteria, and natural degassing. It is assumed that the morning peak of methane content is associated with the release of hydrogen by diazotrophic cyanobacteria, which stimulates the development and activity of hydrogenotrophic methanogens of the genus Methanocalculus.
Effect of the AZOBR_p60123 Plasmid Gene, Encoding the Wzt Protein, on Lipopolysaccharide Synthesis and Biofilm Formation in the Bacterium Azospirillum baldaniorum Sp245
Authors: Petrova L. P. , Evstigneeva S. S. , Filip’echeva Y. A. , Volokhina I. V. , Burygin G. L. , Matora L. Y. , Shelud’ko A. V.
Published: April 2024

Abstract—Inactivation of one of the genes (CDS AZOBR_p60123) of the ABC transporter ATP-binding protein Wzt in the p60123::aphAI mutant of Azospirillum baldaniorum Sp245 and the introduction of an additional copy of this gene into the parent or mutant strain affected the chain-length heterogeneity of O polysaccharides (OPSs) and lipopolysaccharides (LPSs), the OPS and LPS immunochemical characteristics, and the strain properties related to polysaccharide production (biofilm construction). Biofilms of the p60123::aphAI mutant Sp245.4-1-1 accumulated two times less biomass than those of Sp245. Introduction of pRK415-p60123 into the cells of Sp245.4-1-1 or Sp245 resulted in a respective increase or decrease in the ability of the resulting derivative strains to accumulate biofilm biomass, as compared with the original strains.
Calcinating Bacteria in Extreme Ecosystems of the Southern Aral Region
Authors: Kondrasheva K. V. , Umruzokov A. A. , Kalenov S. V. , Merkel A. Yu. , Chernykh N. A. , Slobodkin A. I. , Gavrilov S. N. , Davranov K. D.
Published: April 2024

Abstract—The processes of microbially induced precipitation of calcium carbonates are widespread in natural environments and are an important part of the biogeochemical carbon cycle. These processes comprised the basis of new “biocementation” technologies, which are extensively developing worldwide during the last decade. These technologies are aimed at the construction of novel “self-healing” construction materials, as well as at maintaining the strength of various buildings and structures. Since the optimal conditions for calcite formation are high salinity and alkalinity of the environment, the search for calcifying microorganisms in a variety of ecosystems, including extreme ones, is of interest. At present, many strains of halophilic and halotolerant bacteria, that induce calcination, have already been isolated and tested in pilot industrial processes. Most of these bacteria possess urease activity, which is the main contributor to the binding of calcium ions to insoluble calcium carbonate. A wide variety of natural ecosystems with optimal conditions for the development of calcifying urobacteria, as well as the economic demand for biocementation technologies, stimulate interest in the search for more and more novel strains of these microorganisms. One of the promising resources to be screened for such organisms is the ecosystem of the drying Aral Sea and the adjacent desert and semi-desert Aral region. Here we present the results of screening various extreme ecosystems of the Aral region for the presence of calcifying microorganisms. We obtained 28 pure cultures of heterotrophic aerobic bacteria from samples of plant residues and soils of the Aral Sea region, 4 of which had urease and calcifying activities. Their activities were compared with those of the strains presently used to produce biocementing mixtures. We have identified the phylotypes of putative calcifying microorganisms in microbial communities of desert soil, thermal waters, and bottom sediments of a salt lake, and described the phylogenetic diversity of these communities. Our results indicated the wide distribution of calcifying microorganisms in the ecosystems of the South Aral region and highlighted the expediency of screening them for the new biotechnologically relevant strains of these organisms.
Physiological Characteristics of Saccharomyces cerevisiae Strain Overexpressing Polyphosphatase Ppx1
Authors: Trilisenko L. V. , Valiakhmetov A. Ya. , Kulakovskaya T. V.
Published: April 2024

Abstract—The Ррх1 exopolyphosphatase of yeast is a constitutive protein localized predominantly in the cytoplasm. The purified enzyme hydrolyzes inorganic polyphosphates with high activity; however, in the knockout ∆ppx1 mutant of Saccharomyces cerevisiae the increase in the polyphosphate level was small, and no changes in physiological properties of this mutant were observed. To elucidate the functions of Ppx1, we studied the physiological characteristics of the S. cerevisiae strain overexpressing this enzyme. When cultivated in the YPD medium, the strain overexpressing Ppx1 showed no growth features different from those of the parental strain. The following physiological features of the strain overexpressing Ppx1 were observed at the stationary stage of growth: the level of ATP increased by nine times, the activity of vacuolar ATPase significantly decreased, and the sensitivity to peroxide increased compared to the parental strain. The level of reactive oxygen species doubled, while the degree of lipid oxidation remained the same as in parental strain. Since overexpression of Ppx1 under the culture conditions used did not affect the polyphosphate level, these polymers were not the regulators of the changes described above. Response to oxidative stress and vacuolar ATPase activity in yeasts is known to be regulated by cAMP, while Ppx1 is capable of hydrolyzing this signaling compound. We suggest that one of the functions of Ppx1 in yeasts is participation in the regulation of cAMP level.
Desulfobotulus pelophilus sp. nov., an Alkaliphilic Sulfate-Reducing Bacterium from a Terrestrial Mud Volcano
Authors: Frolova A. A. , Merkel A. Yu. , Kuchierskaya A. A. , Slobodkin A. I.
Published: April 2024

Abstract—An alkaliphilic, sulfate-reducing, anaerobic bacterium (strain H1T) was isolated from a terrestrial mud volcano at the Taman Peninsula, Russia. The cells of the isolate were gram-negative motile vibrios, 1 µm in diameter and 2.0–2.5 μm in length. Strain H1T grew at 14–42°C (optimum at 37°C), pH 8.5–10.5 (optimum at pH 9.5), and NaCl concentrations of 0.5–6% (wt/vol) (optimum at 0.5–1.5%); pyruvate, lactate, butyrate, caproate, or pelargonate were used as electron donors, and elemental sulfur, sulfite, or sulfate were used as electron acceptors. Pyruvate and lactate were fermented. No growth occurred in the presence of oxygen. Thiosulfate, DMSO, fumarate, nitrate, nitrite, arsenate, selenite, and Fe(III) were not used as electron acceptors. Elemental sulfur, thiosulfate, and sulfite were not disproportionated. Glucose, fructose, sucrose, trehalose, galactose, xylose, fumarate, citrate, yeast extract, and peptone were not fermented. Predominant fatty acids were C20:0 (54.2%), C22:0 (24.6%), and C18:0 (11.1%). The genome of strain H1T was 3.66 Mb in size and had G + C DNA content of 51.1%. The genome contained the genes encoding the enzymes of dissimilatory sulfate reduction and β-oxidation of fatty acids. According to the results of analysis of the 16S rRNA gene sequence, Desulfobotulus mexicanus was the organism most closely related to strain Н1Т (98.3% similarity). Based on its phenotypic characteristics and the data of phylogenetic analysis, affiliation of the isolate as member of a novel Desulfobotulus species, Desulfobotulus pelophilus sp. nov., is proposed, with the type strain H1T (=DSM 112796T = VKM B-3697Т =UQM 41590T).
Biodiversity and Metabolic Properties of Bacterial Communities from the Digestive System of the Bivalve Crenomytilus grayanus
Authors: Dunkai T. I. , Bogatyrenko E. A. , Kim A. V.
Published: April 2024

Abstract—Biodiversity of the bacterial communities in the digestive system of Crenomytilus grayanus inhabiting the coastal Sea of Japan waters with chronic anhropogenic pollution was investigated using metabarcoding. Apart from marine bacteria, the taxa typical under contamination with oil (Rhodobacteraceae, Corynebacteriaceae), heavy metals (Asinibacterium), and unprocessed municipal waste (Cloacibacterium, Globicatella) were revealed in the microbiota. A collection of 411 cultured heterotrophic bacterial strains isolated in the course of this study was characterized taxonomically. The intestinal microbiome of the studied mollusks was shown to have a unique composition, depending on their habitat. Ability of bacterial strains isolated from the C. grayanus digestive system to degrade various nutrient substrates (sugars, amino acids, and polysaccharides) and xenobiotics (oil hydrocarbons, bisphenol A, and atrazine) was studied. Most isolates degraded a broad range oforganic substrates; 13% (54 strains) oxidized oil hydrocarbons; 1% (4 strains) oxidized bisphenol A; and 0.5% (2 strains) degraded atrazine. The possible role of the microbiome C. grayanus microbiome in symbiotic digestion and in detoxication of the mollusk is discussed.
Paludisphaera mucosa sp. nov., a Novel Planctomycete of the Family Isosphaeraceae from a Boreal Fen
Authors: Ivanova A. A. , Naumoff D. G. , Kulichevskaya I. S. , Meshcheriakova A. A. , Dedysh S. N.
Published: April 2024

Abstract—Planctomycetes are common inhabitants of northern wetland ecosystems. In this study, a new planctomycete of the genus Paludisphaera, strain Pla2T, was isolated from a boreal fen in Russia. The novel isolate was represented by nonmotile, pink-pigmented, spherical cells that multiplied by budding and occurred singly or were assembled in small aggregates. Strain Pla2T was a chemoorganotrophic, psychrotolerant mesophile with a growth optimum at pH 5.5‒6 and 15‒20°C. The preferred growth substrates were polysaccharides, including xylan, xanthan gum, and phytagel, as well as some sugars. The 16S rRNA gene sequence of strain Pla2T displayed the highest similarity (97.9%) to that of ‘Paludisphaera soli’ JC670T isolated from highland soil of the western Himalayas. With other members of the genus Paludisphaera, “P. rhizosphaerae” JC665T and P. borealis PX4T, this similarity was 97.0 and 93.8%, respectively. The genome of strain Pla2T was 8.21 Mb in size and contained about 6500 protein-coding genes and 3 copies of the rRNA operon. The DNA G + C content was 67 mol %. The average nucleotide identity between the genome sequence of strain Pla2T and those of previously described members of the genus Paludisphaera was between 79.4 and 82.6%. This genotypic distance as well as several phenotypic differences allowed classifying the new planctomycete from a fen as representing a novel species of the genus Paludisphaera, Paludisphaera mucosa sp. nov. with the type strain Pla2T (=KCTC92668T = VKM B-3698T).
Effect of Hormones and Biogenic Amines on Growth and Survival of Enterococcus durans
Authors: El’-Registan G. I. , Zemskova O. V. , Galuza O. A. , Ulanova R. V. , Il’icheva E. A. , Gannesen A. V. , Nikolaev Yu. A.
Published: April 2024

Abstract—Lactic acid bacteria (LAB) are important components of the human microbiome. While they are capable both of synthesis and response to the signals of the human humoral regulatory system (hormones and neuromediators), the phenomenology and mechanisms of the LAB response to these mediators are insufficiently studied. This work showed estrogen to hinder the growth and development of E. durans, while norepinephrine, estrogen, and the brain natriuretic peptide caused dose-dependent extension of the stationary growth phase. This is the first report on stimulation of E. durans biofilm formation by the atrial natriuretic peptide and estrogen. The frequency of persister formation depended on the type of bacterial growth (planktonic or biofilm one) and was higher in the case of biofilm growth. Epinephrine and norepinephrine exhibited dose-dependent stimulation of persister formation in planktonic LAB cultures, while other tested hormones inhibited it. The effect on persister formation in biofilms was different: natriuretic peptides exhibited dose-dependent stimulation of persister formation, and none of the hormones inhibited it significantly. After several months of incubation, E. durans persister cells matured to anaaaaaaaaabiotic dormnt forms with the typical ultrastructural features. The population of E. durans dormant forms was first shown to contain the form with different dormancy depth, including the viable uncultured ones.
Ancylobacter crimeensis sp. nov., a New Species of Aerobic Methylotrophic Bacteria Isolated from Oak Phyllosphere
Authors: Belova A. A. , Kaparullina E. N. , Agafonova N. V. , Grouzdev D. S. , Kopitsyn D. S. , Machulin А. V. , Doronina N. V.
Published: April 2024

Abstract—A new facultative methylotroph, strain 6x-1T, was isolated from the phyllosphere of oak (Quercus pubescens Willd.) on the medium with methanol. Cells were aerobic, gram-negative, not-spore-forming, non-motile short ovoids rods reproducing by binary fission. Growth optimum was at 25‒29°C and pH 7.0‒7.5; growth was inhibited by 1.5% NaCl. Predominant fatty acids were C18:1ω7c and C19:0cyclo. Predominant phospholipids were phosphatidylethanolamine, phosphatidylmonomethylethanolamine, and diphosphatidylglycerol. Tha major ubiquinone was Q10. The 16S rRNA gene sequence of strain 6x-1T exhibited the highest similarity to those of members of the genus Ancylobacter (97.0‒97.4%). Genome analysis of strain 6x-1T and most closely related Ancylobacter strains revealed that the values of ANI (80.7‒83.5%), dDDH (22.4‒23.3%), AAI (72.0‒78.0%), and POCP (62.0‒69.0%) were below the recommended threshold values for prokaryotic species. Genome size of strain 6x-1T was 4.29 × 106 Mb, and G + C content was 67.3%. According to the results of phylogenetic, phylogenomic, phenotypic, and chemotaxonomic analysis, strain 6x-1T (=VKM В-3256T = ССUG 72401T) represents a new species of genus Ancylobacter, for which the name Ancylobacter crimeensis sp. nov. is proposed.