The phylum Acidobacteria is one of the most widespread and abundant on the planet, yet remarkably our knowledge of the role of these diverse organisms in the functioning of terrestrial ecosystems ...remains surprisingly rudimentary. This blatant knowledge gap stems to a large degree from the difficulties associated with the cultivation of these bacteria by classical means. Given the phylogenetic breadth of the Acidobacteria, which is similar to the metabolically diverse Proteobacteria, it is clear that detailed and functional descriptions of acidobacterial assemblages are necessary. Fortunately, recent advances are providing a glimpse into the ecology of members of the phylum Acidobacteria. These include novel cultivation and enrichment strategies, genomic characterization and analyses of metagenomic DNA from environmental samples. Here, we couple the data from these complementary approaches for a better understanding of their role in the environment, thereby providing some initial insights into the ecology of this important phylum. All cultured acidobacterial type species are heterotrophic, and members of subdivisions 1, 3, and 4 appear to be more versatile in carbohydrate utilization. Genomic and metagenomic data predict a number of ecologically relevant capabilities for some acidobacteria, including the ability to: use of nitrite as N source, respond to soil macro-, micro nutrients and soil acidity, express multiple active transporters, degrade gellan gum and produce exopolysaccharide (EPS). Although these predicted properties allude to a competitive life style in soil, only very few of these prediction shave been confirmed via physiological studies. The increased availability of genomic and physiological information, coupled to distribution data in field surveys and experiments, should direct future progress in unraveling the ecology of this important but still enigmatic phylum.
•EPS-SeNPs had a bigger size and ambiguous boundary post gastrointestinal digestion.•Se release from EPS-SeNPs (Se/EPS = 1/1 and 4/3 in SGF) followed a Fickian diffusion.•Se release from EPS-SeNPs ...(Se/EPS = 1/20 in SIF) was governed by erosion (chain relaxation).•Se release (Se/EPS = 1/1 and 4/3 in SIF) was governed by both diffusion and erosion.•The Se/EPS = 1/20 sample was stable in SGF and active in SIF with controlled Se release potential.
This work investigated selenium (Se) release kinetics and mechanism from exopolysaccharide-selenium nanoparticles (EPS-SeNPs, Se/EPS = 1/20, 1/1 and 4/3) in simulated gastric (SGF) and intestinal fluids (SIF) using kinetics models of Zero order, First order, Higuchi, Hixson-Crowell and Korsmeyer-Peppas. EPS-SeNPs showed an increase in size from 80–125 nm to 250–320 nm and more ambiguous boundary after gastrointestinal digestion. Se/EPS ratio and pH had significant influence on Se release. Se release kinetics from EPS-SeNPs (Se/EPS = 1/1 and 4/3 in SGF) followed a classical Fickian diffusion, in contrast to an erosion governed by macromolecular chains relaxation for Se/EPS = 1/20 in SIF. Se release from EPS-SeNPs (Se/EPS = 1/1 and 4/3 in SIF) was well-fitted to Korsmeyer-Peppas model and followed a non-Fickian mechanism controlled by both diffusion and erosion. Additionally, EPS-SeNPs (Se/EPS = 1/20) showed a low Se release after SGF digestion, but a high release after SIF digestion, suggesting its application in controlled release of Se-enriched supplements for Se-deficiency treatment.
Adsorption is an effective and reliable method to recover phosphorus (P) from sewages. Extracellular polymeric substances (EPS) and agarose are common polysaccharides bioresources, and their ...carboxylic and phenolic hydroxyl groups can directly adsorb P via ion exchange and hydrogen bonding mechanisms. Here, we designed EPS-based and Fe-modified hydrogels (agarose (AG)- and agarose-humic (AH)- based hydrogels) for P recovery. The results showed that AG and AH hydrogels could adsorb 33.9 and 67.7 mg P g−1, respectively. Both as-developed hydrogels showed > 75% of the maximal adsorption capacity in the tested pH conditions (3−10). Coexisting anions (i.e., SO42-, NO3-, and CO32-) did not significantly affect the adsorption performance, except for CO32- which inhibited the process. Intraparticle diffusion controlled the adsorption process. After adsorption, large amounts of FePO4 and Fe2(HPO4)3 were generated in the hydrogels, confirming that ligand exchange was the major driving force.
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•EPS-based hydrogels are made from agarose and humic acid.•EPS-based hydrogel appeared to have excellent phosphorus adsorption performance.•Ligand exchange is the major driving force for hydrogels to trap phosphate.
The study of hydrothermal travertines contributes to the understanding of the interaction between physico‐chemical processes and microbial mats in carbonate precipitation. Three active travertine ...sites were investigated in Central Italy to characterise the types of carbonate precipitates and the associated microbial mats at varying physico‐chemical parameters. Carbonate precipitated fabrics at the decimetre to millimetre‐scale and microbial mat composition vary with decreasing water temperature: (a) at relatively higher temperature (55–44°C) calcite and aragonite crystals precipitate on microbial mats of Chloroflexi and sulphur‐oxidizing microbes forming filamentous streamer fabrics with sparse cyanobacteria, (b) at intermediate temperature (44–40°C), rafts, coated gas bubbles and dendrites are associated with Spirulina cyanobacteria and other filamentous and rod‐shaped cyanobacteria, (c) low temperature (34–33°C) laminated crusts and oncoids forming in a terraced slope system are associated with diverse Oscillatoriales and Nostocales filamentous cyanobacteria, Spirulina and diatoms. At the microscale, carbonate precipitates are similar in the three sites consisting of prismatic calcite crystals organised in radial rosettes or fibrous aragonite spherulites (40–300 µm in diameter), overlying or embedded in Extracellular Polymeric Substances. Clotted peloidal micrite dominates at temperatures <40°C, also encrusting filamentous microbes. Carbonates are associated with gypsum crystals; extracellular polymeric substances are enriched in silicon, aluminium, magnesium, calcium, phosphorous and sulphur; authigenic aluminium‐silicates form aggregates on Extracellular Polymeric Substances. This study confirms that microbial communities in hydrothermal settings vary as a function of water temperature. Carbonate precipitates at the microscale are similar in the three settings, despite different microbial communities, suggesting that travertine precipitation, driven by carbon dioxide degassing, is influenced by biofilm extracellular polymeric substances acting as a substrate for crystal nucleation (Extracellular Polymeric Substances‐mediated mineralization) and affecting the resultant fabric types, independently from specific microbial community composition and metabolism.
Three active travertine sites were investigated in Central Italy to identify the types of carbonate precipitates and the associated microbial mats at varying physico‐chemical parameters. This study confirms that microbial communities in hydrothermal settings vary as a function of water temperature. Carbonate crystals at the microscale are similar in the three settings, despite different microbial communities, because of EPS‐mediated carbonate precipitation.
Microalgae can excrete exopolymer substances (EPS) with a potential to form hetero-aggregates with microplastic particles. In this work, two freshwater (Microcystis panniformis and Scenedesmus sp.) ...and two marine (Tetraselmis sp. and Gloeocapsa sp.) EPS producing microalgae were exposed to different microplastics. In this study, the influence of the microplastic particles type, size and density in the production of EPS and hetero-aggregates potential was studied. Most microalgae contaminated with microplastics displayed a cell abundance decrease (of up to 42%) in the cultures. The results showed that the formed aggregates were composed of microalgae and EPS (homo-aggregates) or a combination of microalgae, EPS and microplastics (hetero-aggregates). The hetero-aggregation was dependent on the size and yield production of EPS, which was species specific. Microcystis panniformis and Scenedesmus sp. exhibited small EPS, with a higher propension to disaggregate, and consequently lower capabilities to aggregate microplastics. Tetraselmis sp. displayed a higher ability to aggregate both low and high-density microplastics, being partially limited by the size of the microplastics. Gloeocapsa sp. had an outstanding EPS production and presented excellent microplastic aggregation capabilities (adhered onto the surface and also incorporated into the EPS). The results highlight the potential of microalgae to produce EPS and flocculate microplastics, contributing to their vertical transport and consequent deposition. Thus, this work shows the potential of microalgae as biocompatible solutions to water microplastics treatment.
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•Specific microalgae can excrete EPS with favourable characteristics to aggregate microplastics and form hetero-aggregates.•Microalgae can colonize microplastics and use the EPS to adhere and incorporate the particles.•Microplastics colonization and hetero-aggregation contribute to its vertical transport and deposition.
Microalgae extracellular polymeric substances have the potential to aggregate microplastics, contributing to their vertical transport and deposition.
We evaluated whether EPs
7630 prescription in patients with acute sinusitis (AS) is associated with less frequent recurrence of AS, occurrence of chronic sinusitis or nasal polyps, or fewer ...antibiotic prescriptions.
This retrospective cohort study used electronic medical records from the IQVIA Disease Analyzer database. Associations between initial therapy EPs
7630, antibiotics, intranasal corticosteroid (INCS), or corticosteroid-free nasal spray within 3 days of AS diagnosis and AS recurrence, incidence of chronic sinusitis or nasal polyps or rate of antibiotic prescription were studied using multivariable Cox or logistic regression models, adjusting for sex, age, insurance status, month of diagnosis, and comorbidity.
A total of 216,360 patients were analyzed. INCS prescription was associated with a higher risk of recurrent AS (HR: 1.40; 95% CI: 1.01-1.92) and a higher incidence of chronic sinusitis or nasal polyp diagnosis (HR: 1.39; 95% CI: 1.01-1.92) compared to EPs
7630. Initial antibiotic therapy was significantly associated with higher risk of new antibiotic prescription in the period of 31-365 days after the index date compared to EPs
7630 (OR: 2.20; 95% CI: 1.66-2.92).
EPs
7630 prescription is associated with long-term benefits in AS patients. EPs
7630 can help to reduce inappropriate antibiotic use and might reduce the risk of chronic sinusitis or nasal polyps.
The physics of exceptional points Heiss, W D
Journal of physics. A, Mathematical and theoretical,
11/2012, Letnik:
45, Številka:
44
Journal Article
Recenzirano
Odprti dostop
A short résumé is given about the nature of exceptional points (EPs) followed by discussions about their ubiquitous occurrence in a great variety of physical problems. EPs feature in classical as ...well as in quantum mechanical problems. They are associated with symmetry breaking for -symmetric Hamiltonians, where a great number of experiments has been performed, in particular in optics, and to an increasing extent in atomic and molecular physics. EPs are involved in quantum phase transition and quantum chaos; they produce dramatic effects in multichannel scattering, specific time dependence and more. In nuclear physics, they are associated with instabilities and continuum problems. Being spectral singularities they also affect approximation schemes. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to 'Quantum physics with non-Hermitian operators'.
•New polysaccharide hydrogels were developed for adsorption of heavy metal ions.•Polysaccharide hydrogels were obtained by graft polymerization technique.•Influence of salecan amount on the gel ...structure and adsorption performance was investigated.•Adsorption data were fitted the best with the Freundlich isotherm models.
Polysaccharides are an important class of materials that are often exploited in the fields of food, agriculture, biomedical engineering and wastewater treatment owing to their unique and tunable properties. In this work, we utilize an inexpensive and sustainable extracellular polysaccharide salecan (EPS), which is produced by bacterium Agrobacterium sp. ZX09, as a hydrogel matrix, poly(3-sulfopropyl methacrylate potassium salt) (PSM) as side chains to fabricate EPS-grafted-PSM adsorbents through a simple one-pot approach. Scanning electron microscope, X-ray diffraction, Fourier transformed infrared spectroscopy, rheometry and thermogravimetry were conducted to characterize the physicochemical properties of resultant adsorbents. We noticed that EPS not only served as the host chains of network to adjust the water uptake ability of adsorbents, but also endued them with tunable polarity. Further, the adsorption behaviors of developed adsorbents to copper ions (Cu2+) were explored: these gels present high absorption ability for Cu2+ through a chemical adsorption process which well described by Freundlich isotherm and pseudo-second-order kinetic models. In summary, the approach exhibited in this work opens a new avenue to design polysaccharide-based materials for Cu2+ adsorption.
Anammox bacteria tend to self-aggregate, and biofilm-based anammox processes are widely used as sustainable alternative methods for nitrogen removal from wastewater. However, the mechanism for the ...initial adhesion of anammox bacteria remains unclear. In this work, extracellular polymeric substances (EPS) were extracted separately from anammox granules and then characterized by multi-methods. The adhesion properties of anammox consortia to biotic and abiotic surfaces were examined separately before and after the extraction of three stratified EPS, using aggregation assays and a quartz crystal microbalance technique with dissipation monitoring, respectively. The extraction of each of the three stratified EPS gradually increased the initial aggregation of anammox consortia from 77.6 ± 3.0% to 85.2 ± 2.6%. Fourier transform infrared spectrometry confirmed that the aggregation of anammox consortia depended largely on the interactions between functional groups on the cell surfaces. All three stratified EPS had positive effects on the initial adhesion rate and mass of anammox consortia to abiotic surfaces. More importantly, the structure of the adhered layer was more compact before the extraction of each of the three stratified EPS. We therefore hypothesized that the initial adhesion among anammox consortia was due to the ability of the anammox bacteria to express adhesion molecules on the bacterial surfaces and that the three stratified EPS were excreted to adhere inert particulates and form a compact biofilm structure. This study clarifies the role of stratified EPS on the initial formation of anammox biofilms and provides a theoretical basis for accelerating the formation of anammox biofilms.
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•Role of stratified EPS in anammox consortia adhesion was studied separately.•The aggregation of anammox consortia was attributed to the bacteria themselves.•All stratified EPS stimulated anammox consortia adhering to abiotic surfaces.•All stratified EPS favored formation of a compact biofilm structure.
The article presents the analysis of the thermal performance of an EPS-based system finished with different plaster coatings. The analysis is based on the results achieved at the field site station. ...The analysis took into account the type of plaster, its texture and the orientation of the exterior wall finish relative to its facing which the moisture content inside the EPS and under the plaster coating is also dependent. It is noted here that the accumulation of moisture takes place within the expanded polystyrene. It was also found that the stabilization of moisture levels in the insulation material depends on the type of external plaster coating. The actual thermal performance of the insulation material was analyzed using the results of the evaluation of the moisture properties in the expanded polystyrene under the plaster coating at the field site. The moisture results confirm that there is an accumulation of moisture in the insulation material, which has a significant impact on the value of thermal resistance, with the largest differences found in the north and west facing exterior wall finishes.
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