Brussowvirus SW13 Requires a Cell Surface-Associated Polysaccharide To Recognize Its Streptococcus thermophilus Host

Four bacteriophage-insensitive mutants (BIMs) of the dairy starter bacterium Streptococcus thermophilus UCCSt50 were isolated following challenge with Brussowvirus SW13. The BIMs displayed an altered sedimentation phenotype. Whole-genome sequencing and comparative genomic analysis of the BIMs uncovered mutations within a family 2 glycosyltransferase-encoding gene (orf06955(UCCSt50)) located within the variable region of the cell wall-associated rhamnose-glucose polymer (Rgp) biosynthesis locus (designated the rgp gene cluster here). Complementation of a representative BIM, S. thermophilus B1, with native orf06955(UCCSt50) restored phage sensitivity comparable to that of the parent strain. Detailed bioinformatic analysis of the gene product of orf06955(UCCSt50) identified it as a functional homolog of the Lactococcus lactis polysaccharide pellicle (PSP) initiator WpsA. Biochemical analysis of cell wall fractions of strains UCCSt50 and B1 determined that mutations within orf06955(UCCSt50) result in the loss of the side chain decoration from the Rgp backbone structure. Furthermore, it was demonstrated that the intact Rgp structure incorporating the side chain structure is essential for phage binding through fluorescence labeling studies. Overall, this study confirms that the rgp gene cluster of S. thermophilus encodes the biosynthetic machinery for a cell surface-associated polysaccharide that is essential for binding and subsequent infection by Brussowviruses, thus enhancing our understanding of S. thermophilus phage-host dynamics.IMPORTANCE Streptococcus thermophilus is an important starter culture bacterium in global dairy fermentation processes, where it is used for the production of various cheeses and yogurt. Bacteriophage predation of the species can result in substandard product quality and, in rare cases, complete fermentation collapse. To mitigate these risks, it is necessary to understand the phage-host interaction process, which commences with the recognition of, and adsorption to, specific host-encoded cell surface receptors by bacteriophage(s). As new groups of S. thermophilus phages are being discovered, the importance of underpinning the genomic elements that specify the surface receptor(s) is apparent. Our research identifies a single gene that is critical for the biosynthesis of a saccharidic moiety required for phage adsorption to its S. thermophilus host. The acquired knowledge provides novel insights into phage-host interactions for this economically important starter species

Oxygen transport in Pr nickelates: Elucidation of atomic-scale features

Pr2NiO4+δ oxide with a layered Ruddlesden–Popper structure is a promising material for SOFC cathodes and oxygen separation membranes due to a high oxygen mobility provided by the cooperative mechanism of oxygen migration involving both interstitial oxygen species and apical oxygen of the NiO6 octahedra. Doping by Ca improves thermodynamic stability and increases electronic conductivity of Pr2 − xCaxNiO4+δ, but decreases oxygen mobility due to decreasing the oxygen excess and appearing of 1–2 additional slow diffusion channels at x ≥ 0.4, probably, due to hampering of cooperative mechanism of migration. However, atomic-scale features of these materials determining oxygen migration require further studies. In this work characteristics of oxygen diffusion in Pr2 − xCaxNiO4+δ (x = 0–0.6) are compared with results of the surface analysis by X-ray photoelectron spectroscopy and modeling of the interstitial oxygen migration by the plane-wave density functional theory calculations. According to the X-ray photoelectron spectroscopy data, the surface is enriched by Pr for undoped sample and by Ca for doped ones. The O1s peak at ~531 eV corresponding to a weakly bound form of surface oxygen located at Pr cations disappears at ~500 °C. Migration of interstitial oxygen was modeled for a I4/mmm phase of Pr2NiO4+δ. The interstitial oxygen anion repulses the apical one in the NiO6 octahedra pushing it into the tetrahedral site between Pr cations. The calculated activation barrier of this migration is equal to 0.585 eV, which reasonably agrees with the experimental value of 0.83 eV obtained by the oxygen isotope exchange method. At the same time, for the model compound Ca2NiO4+δ, obtained by isomorphic substitution of Pr by Ca in Pr2NiO4+δ, calculations implied formation of the peroxide ion comprised of interstitial and lattice oxygen species not revealed in the case of incomplete substitution (up to PrCaNiO4+δ composition). Hence, calculations in the framework of the plane-wave density functional theory provide a realistic estimation of specificity of oxygen migration features in Pr2NiO4+δ doped by alkaline-earth metals. © 2019 Elsevier B.V.Russian Science Foundation, RSF: 16-13-00112Support by Russian Science Foundation (Project 16-13-00112 ) is gratefully acknowledged

High-Temperature Behavior, Oxygen Transport Properties, and Electrochemical Performance of Cu-Substituted Nd1.6Ca0.4NiO4+δ Electrode Materials

In this study, Nd1.6Ca0.4Ni1−yCuyO4+δ-based electrode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) are investigated. Materials of the series (y = 0–0.4) are obtained by pyrolysis of glycerol-nitrate compositions. The study of crystal structure and high-temperature stability in air and under low oxygen partial pressure atmospheres are performed using high-resolution neutron and in situ X-ray powder diffraction. All the samples under the study assume a structure with Bmab sp.gr. below 350◦C and with I4/mmm sp.gr. above 500◦C. A transition in the volume thermal expansion coefficient values from 7.8–9.3 to 9.1–12.0 × 10−6, K−1 is observed at approximately 400◦C in air and 500◦C in helium.The oxygen self-diffusion coefficient values, obtained using isotope exchange, monotonically decrease with the Cu content increasing, while concentration dependence of the charge carriers goes through the maximum at x = 0.2. The Nd1.6Ca0.4Ni0.8Cu0.2O4+δ electrode materialdemonstrates chemical compatibility and superior electrochemical performance in the symmetrical cells with Ce0.8Sm0.2O1.9, BaCe0.8Sm0.2O3−δ, BaCe0.8Gd0.19Cu0.1O3−δ and BaCe0.5Zr0.3Y0.1Yb0.1O3−δ solid electrolytes, potentially for application in IT-SOFCs. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.122013100200-2; Ministry of Education and Science of the Russian Federation, Minobrnauka: AAAA-A21-121011390009-1; Ural Branch, Russian Academy of Sciences, UB RAS: 122020100324-3Material synthesis, sample preparation, and electrochemical studies were performed in the framework of budget tasks for the Institute of High Temperature Electrochemistry, UB RAS, project № 122020100324-3. The standard characterization of powder and ceramic materials was carried out at the Shared Access Centre “Composition of Compounds” of the Institute of High Temperature Electrochemistry, UB RAS. The synchrotron XRD experiments were performed at the shared research center SSTRC on the basis of the Novosibirsk VEPP-3 complex at BINP SB RAS. The in situ XRD study was carried out using the facilities of the shared research center “National Center of Investigation of Catalysts” at the Boreskov Institute of Catalysis (BIC). The part of the reported study concerning the crystal structure of the samples was funded within the framework of budget project for Synchrotron radiation facility SKIF, Boreskov Institute of Catalysis.BIC support of the isotope exchange study by the Ministry of Science and Higher Education of the Russian Federation projects AAAA-A21-121011390009-1 and AAAA-A21-121011390007-7 is greatly acknowledged. XPS study of the electrode materials was partly performed in the framework of the budget task for the Institute of Metallurgy, UB RAS, project № 122013100200-2 using the equipment of the Shared Access Centre “Ural-M” of the Institute of Metallurgy, UB RAS.Acknowledgments: Material synthesis, sample preparation, and electrochemical studies were performed in the framework of budget tasks for the Institute of High Temperature Electrochemistry, UB RAS, project №122020100324-3. The standard characterization of powder and ceramic materials was carried out at the Shared Access Centre “Composition of Compounds” of the Institute of High Temperature Electrochemistry, UB RAS. The synchrotron XRD experiments were performed at the shared research center SSTRC on the basis of the Novosibirsk VEPP-3 complex at BINP SB RAS. The in situ XRD study was carried out using the facilities of the shared research center “National Center of Investigation of Catalysts” at the Boreskov Institute of Catalysis (BIC). The part of the reported study concerning the crystal structure of the samples was funded within the framework of budget project for Synchrotron radiation facility SKIF, Boreskov Institute of Catalysis.BIC support of the isotope exchange study by the Ministry of Science and Higher Education of the Russian Federation projects AAAA-A21-121011390009-1 and AAAA -A21-121011390007-7 is greatly acknowledged. XPS study of the electrode materials was partly performed in the framework of the budget task for the Institute of Metallurgy, UB RAS, project № 122013100200-2 using the equipment of the Shared Access Centre “Ural-M” of the Institute of Metallurgy, UB RAS

Chemical Analysis of Cellular and Extracellular Carbohydrates of a Biofilm-Forming Strain Pseudomonas aeruginosa PA14

Background: Pseudomonas aeruginosa is a Gram-negative bacterium and an opportunistic pathogen, which causes persisting life-threatening infections in cystic fibrosis (CF) patients. Biofilm mode of growth facilitates its survival in a variety of environments. Most P. aeruginosa isolates, including the non-mucoid laboratory strain PA14, are able to form a thick pellicle, which results in a surface-associated biofilm at the air-liquid (A\ufffdL) interface in standing liquid cultures. Exopolysaccharides (EPS) are considered as key components in the formation of this biofilm pellicle. In the non-mucoid P. aeruginosa strain PA14, the \ufffd\ufffdscaffolding\ufffd\ufffd polysaccharides of the biofilm matrix, and the molecules responsible for the structural integrity of rigid A\ufffdL biofilm have not been identified. Moreover, the role of LPS in this process is unclear, and the chemical structure of the LPS O-antigen of PA14 has not yet been elucidated. Principal Findings: In the present work we carried out a systematic analysis of cellular and extracellular (EC) carbohydrates of P. aeruginosa PA14. We also elucidated the chemical structure of the LPS O-antigen by chemical methods and 2-D NMR spectroscopy. Our results showed that it is composed of linear trisaccharide repeating units, identical to those described for P. aeruginosa Lanyi type O:2a,c (Lanyi-Bergman O-serogroup 10a, 10c; IATS serotype 19) and having the following structure: -4)-a-L-GalNAcA-(1\ufffd3)-a-D-QuiNAc-(1\ufffd3)- a-L-Rha-(1-. Furthermore, an EC O-antigen polysaccharide (EC O-PS) and the glycerol-phosphorylated cyclic b-(1,3)-glucans were identified in the culture supernatant of PA14, grown statically in minimal medium. Finally, the extracellular matrix of the thick biofilm formed at the A-L interface contained, in addition to eDNA, important quantities (at least ,20% of dry weight) of LPS-like material. Conclusions: We characterized the chemical structure of the LPS O-antigen and showed that the O-antigen polysaccharide is an abundant extracellular carbohydrate of PA14. We present evidence that LPS-like material is found as a component of a biofilm matrix of P. aeruginosa.Peer reviewed: YesNRC publication: Ye

Novel materials for solid oxide fuel cells cathodes and oxygen separation membranes: Fundamentals of oxygen transport and performance

In the field of modern hydrogen energy, obtaining pure hydrogen and syngas and then being able to use them for green energy production are significant problems. Developing solid oxide fuel cells (SOFC) and catalytic membranes for oxygen separation as well as materials for these devices is one of the most likely ways to solve these problems. In this work, the authors’ recent studies in this field are reviewed; the fundamentals of developing materials for SOFC cathodes and oxygen separation membranes’ permselective layers based on research of their oxygen mobility and surface reactivity are presented. Ruddlesden – Popper phases Ln2–xCaxNiO4+δ (LnCNO) and perovskite-fluorite nanocomposites PrNi0.5Co0.5O3–δ–Ce0.9Y0.1O2–δ (PNC–YDC) were studied by isotope exchange of oxygen with C18O2 and 18O2 in flow and closed reactors. For LnCNO a high oxygen mobility was shown (D* ~ 10–7 cm2/s at 700 °C), being provided by the cooperative mechanism of oxygen migration involving both regular and highly-mobile interstitial oxygen. For PNC–YDC dominated a wide fast diffusion channel via fluorite phase and interphases due to features of the redistribution of cations resulting in superior oxygen mobility (D* ~ 10–8 cm2/s at 700 °C). After optimization of composition and nanodomain structure of these materials, as cathodes of SOFC they provided a high power density, while for asymmetric supported oxygen separation membranes – a high oxygen permeability. © 2020Support of different parts of the work by the Russian Science Foundation (Project 16-13-00112) and the budget project №AAAA-A17-117041110045-9 for Boreskov Institute of Catalysis is gratefully acknowledged. The authors from the Ural Federal University are grateful to the Government of the Russian Federation (Agreement 02.A03.21.0006, Act 211). Ce 0.9 Y 0.1 O 2–δ |Ce 0.9 Gd 0.1 O 2–δ |Ni/Zr 0.84 Y 0.16 O 2–δ anodic half-cells and Ni/Al foam substrates were kindly provided by H.C. Starck, Germany and Powder Metallurgy Institute NAN Belarus, respectively. Authors would like to appreciate International Conference on Advances in Energy Systems and Environmental Engineering (ASEE19, Wroclaw, Poland, June 9-12, 2019) Organization Committee

СОСТАВ И МИКРОСТРУКТУРА КОРАЛЛОВИДНЫХ МОЧЕВЫХ КАМНЕЙ. ТЕОРИИ РОСТА

For the first time the composition and microstructure of large (more than 2 cm) urinary stones, including staghorn stones, were studied according to their volume by a set of techniques (X-ray, X-ray microanalysis, scanning electron microscopy, infrared spectroscopy, spectrophotometry, gas chromatography with a flame ionization detector), as well as the composition of the urine, in which their formation and growth occurred. The results and analysis combined with the published data have allowed to clarify and expand the theories of formation and suggest the process of urinary stones growth.В первые комплексом методов (рентгенография, рентгеноспектральный микроанализ, скани-рующая электронная микроскопия, ИК-спектроскопия, спектрофотометрия, газовая хрома-тография с пламенно-ионизационной детекцией) выполнено исследование мочевых камней (состав, микроструктура), включая коралловидные камни, большого (>2 см) размера по их объему, а также исследование состава мочи, в котором произошло их образование и рост. Анализ полученных результатов совместно с литературными данными позволил уточнить и расширить теории образования мочевых камней и предложить объяснение процесса их роста

The role of polysaccharide intercellular adhesin (PIA) in Staphylococcus epidermidis adhesion to host tissues and subsequent antibiotic tolerance

The aim of this study was to determine the role of polysaccharide intercellular adhesin (PIA) in Staphylococcus epidermidis adhesion to host tissues and subsequent antibiotic tolerance. The adherence of S. epidermidis 1457 and the mutant defective in PIA production (1457-M10) to urinary epithelium and endothelium was estimated by colony counting. Minimum bactericidal concentration and mean reduction of cellular activity (XTT) following antibiotic exposure was determined for planktonic and adhered bacteria. S. epidermidis 1457 adhered to a greater extent to both cells than the mutant strain. The adhered strains had a significantly higher antimicrobial tolerance than their planktonic counterparts. The mutant strain was, in general, the most susceptible to the antibiotics assayed. In conclusion, PIA may influence S. epidermidis adherence to host tissues and their antimicrobial susceptibility. Initial adhesion may be the main step for the acquisition of resistance in S. epidermidis

Состояние палладия и меди в свежеприготовленном катализаторе PdCl2−CuCl2/γ−Al2O3 низкотемпературного окисления монооксида углерода

The EXAFS/XANES, XRD, SEM methods were used for examination of freshly prepared low temperature carbon monoxide oxidation in air catalyst PdCl2-CuCl2/γ-Al2O3 active components states. The Cu2Cl(OH)3 phase with particle size 100-300 nm and tetrachloropalladat particles were identified on γ-Al2O3 surface. According to EXAFS data one of the palladium chloride bonds is longer then another ones. There is no direct interaction between palladium and copper, i.e. there is no common active center including palladium and copper on the γ-Al2O3 surface responsible on the low temperature carbon monoxide oxidation in air.Методами рентгеновской спектроскопии поглощения (EXAFS/XANES), порошковой рентгеновской дифрактометриии, растровой электронной микроскопии (РЭМ) изучено состояние активных компонентов свежеприготовленного катализатора PdCl2−CuCl2/γ−Al2O3 низкотемпературного окисления монооксида углерода в воздухе. Показано, что на поверхности γ−Al2O3 находится кристаллическая фаза Cu2Cl(OH)3 с размерами частиц 100-300 нм и палладий в аморфном состоянии. По данным EXAFS, локальное окружение палладия - четыре атома хлора, образующие плоский квадрат с одной более длинной связью Pd-Cl. Прямого контакта между палладием и медью не обнаружено, то есть, на поверхности катализатора отсутствует единый активный центр, ответственный за проведение реакции окисления монооксида углерода кислородом

Morphological, Physiological and Genetic Characteristics of Populations of the Main Plague Host Rhombomys opimus Licht., 1823 in the Central Asian Desert Natural Focus of Plague

Revealed by morphological characters, physiological status, and genetic diversity of populations of the main plague host Rhombomys opimus Licht., 1823 in Central Asia desert natural focus is described.Differences in the skull parameters of R. opimus from different populations were revealed. It’s shown that gerbils from Moyunkum are separate autonomous populations group. Samples from Moyunkum and Mangyshlak differed from other samples. In Balkhash-Alakol depression found two regional complexes: Pre-Balkhash and Dzungarian.Study results of free amino acids level in R. opimus blood serum obtained by gas-liquid chromatography of blood sera from animals captured in different zones of Central Asian focus gave statistically significant differences. To determine genetic variability in ecological and geographical isolation of R. opimus populations the DNA was genotyped.DNA samples analysis combined the studied gerbil from the desert focus into four clusters with eighteen haplotypes. R. opimus sequence analysis taking into account data from territories of Iran, Kazakhstan and China, clustered into three large clusters. First cluster combined the sequences of Kazakhstan and China samples, while great gerbil captured in Kazakhstan is located in a separate treasure. Second and third clusters include sequences of a great gerbil captured in Iran