Dramatic loss of microbial viability in bentonite exposed to heat and gamma radiation: implications for deep geological repository.

Bentonite is an integral part of the engineered barrier system (EBS) in deep geological repositories (DGR) for nuclear waste, but its indigenous microorganisms may jeopardize long-term EBS integrity. To predict microbial activity in DGRs, it is essential to understand microbial reactions to the early hot phase of DGR evolution. Two bentonites (BCV and MX-80) with varied bentonite/water ratios and saturation levels (compacted to 1600 kg.

An acidic exopolysaccharide α-D-galacturono-β-D-glucan produced by the cyanobacterium Scytonema sp.

Some cyanobacteria produce a wide range of secondary metabolites, some of which are of industrial interest. Exopolysaccharides, particularly interesting among them, represent relatively complex primary structures with interesting bioactivity, biodegradability and specific applications. Cultivation of the freshwater cyanobacterium Scytonema sp.

Dendrobium officinale polysaccharides-chemical properties and pharmacodynamic effects on the airways in experimental conditions.

The study aimed to analyze the effects of Dendrobium polysaccharides on the cough and airway reactivity and compare them with the effects of clinically used antitussives (codeine phosphate and butamirate citrate) and bronchodilators (salbutamol), using the guinea pig test system. Dendrobium officinale polysaccharides contained proteins (4.0 wt%) and phenolic compounds (1.

Microbial involvement in iodine cycle: mechanisms and potential applications.

Stable iodine isotopes are essential for humans as they are necessary for producing thyroid gland hormones. However, there are hazardous radioactive iodine isotopes that are emitted into the environment through radioactive waste generated by nuclear power plants, nuclear weapon tests, and medical practice. Due to the biophilic character of iodine radionuclides and their enormous biomagnification potential, their elimination from contaminated environments is essential to prevent the spread of radioactive pollution in ecosystems.

Structural properties of the biologically active Dictyosphaerium chlorelloides exopolysaccharide α-d-manno-α-l-rhamno-α-d-(2-O-methyl)-galactan.

Structure of biopolymers produced by microalgae plays an important role for their potential biological activity prediction and applications. Previously isolated and well characterized dominant fractions (Dch5-8) from ion-exchange chromatography separation of the biologically active microalga Dictyosphaerium chlorelloides exopolysaccharide (Dch) were pooled and partially acid hydrolyzed. The dominant sugar components in the combined Dch5-8 fraction were Gal and its 2-O-methyl derivative, Rha and Man, all accounting for about 94 mol% of total amount of sugars.

Investigating the initial steps of auricin biosynthesis using synthetic biology.

Streptomyces lavendulae subsp. lavendulae CCM 3239 (formerly Streptomyces aureofaciens CCM 3239) contains a type II polyketide synthase (PKS) biosynthetic gene cluster (BGC) aur1 whose genes were highly similar to angucycline BGCs. However, its product auricin is structurally different from all known angucyclines.

Solid-Water Interface Interaction of Selenium with Fe(II)-Bearing Minerals and Aqueous Fe(II) and S(-II) Ions in the Near-Field of the Radioactive Waste Disposal System.

Selenium can be highly toxic in excess for both animals and humans. However, since its mobile forms can be easily adsorbed with ferric minerals, its mobility in the natural oxic environment is generally not an issue. Still, the removal and immobilization of the long-lived radioactive isotope Se from the contaminated anoxic waters is currently a significant concern.

Current Strategies for Selenium and Iodine Biofortification in Crop Plants.

Selenium and iodine are essential trace elements for both humans and animals. Among other things, they have an essential role in thyroid function and the production of important hormones by the thyroid gland. Unfortunately, in many areas, soils are deficient in selenium and iodine, and their amount is insufficient to produce crops with adequate contents to cover the recommended daily intake; thus, deficiencies have an endemic character.

Structural features of biologically active extracellular polysaccharide produced by green microalgae Dictyosphaerium chlorelloides.

Ion-exchange chromatography of the biologically active extracellular biopolymer produced by D. chlorelloides yielded ten fractions differing in yield, protein content, monosaccharide composition and molecular weight distribution. Their sugar compositional analyses showed rhamnogalactans, substituted to different extent by mannose and glucose, as a dominant EPS component in all fractions (91 %) except one containing arabinogalactan (7 %).

Production of Methyl-Iodide in the Environment.

Iodine is an essential micronutrient for most of the living beings, including humans. Besides its indispensable role in animals, it also plays an important role in the environment. It undergoes several chemical and biological transformations resulting in the production of volatile methylated iodides, which play a key role in the iodine's global geochemical cycle.

Lactylated acidic exopolysaccharide produced by the cyanobacterium Nostoc cf. linckia.

Cyanobacteria produce a wide range of metabolites of interest for industrial or medical use. The cultivation of freshwater Nostoc cf. linckia yielded 5.

Fungal Mobilization of Selenium in the Presence of Hausmannite and Ferric Oxyhydroxides.

Bioleaching of mineral phases plays a crucial role in the mobility and availability of various elements, including selenium. Therefore, the leachability of selenium associated with the surfaces of ferric and manganese oxides and oxyhydroxides, the prevailing components of natural geochemical barriers, has been studied in the presence of filamentous fungus. Both geoactive phases were exposed to selenate and subsequently to growing fungus for three weeks.

Bioleaching of Manganese Oxides at Different Oxidation States by Filamentous Fungus .

This work aimed to examine the bioleaching of manganese oxides at various oxidation states (MnO, MnO·MnO, MnO and MnO) by a strain of the filamentous fungus , a frequent soil representative. Our results showed that the fungus effectively disintegrated the crystal structure of selected mineral manganese phases. Thereby, during a 31-day static incubation of oxides in the presence of fungus, manganese was bioextracted into the culture medium and, in some cases, transformed into a new biogenic mineral.

The Effect of High Selenite and Selenate Concentrations on Ferric Oxyhydroxides Transformation under Alkaline Conditions.

Iron-based nanomaterials have high technological impacts on various pro-environmental applications, including wastewater treatment using the co-precipitation method. The purpose of this research was to identify the changes of iron nanomaterial's structure caused by the presence of selenium, a typical water contaminant, which might affect the removal when the iron co-precipitation method is used. Therefore, we have investigated the maturation of co-precipitated nanosized ferric oxyhydroxides under alkaline conditions and their thermal transformation into hematite in the presence of selenite and selenate with high concentrations.

Optimizing acid hydrolysis for monosaccharide compositional analysis of Nostoc cf. linckia acidic exopolysaccharide.

The exact estimation of monosaccharide composition is important in the primary structure elucidation of polysaccharides. An acid hydrolysis is usually performed for glycosidic bonds cleavage and releasing of monosaccharides. In this study, optimal conditions of total acid hydrolysis using trifluoroacetic acid (TFA) of acidic lactylated Nostoc cf.

An efficient system for stable markerless integration of large biosynthetic gene clusters into Streptomyces chromosomes.

The bacteria of the genus Streptomyces are among the most important producers of biologically active secondary metabolites. Moreover, recent genomic sequence data have shown their enormous genetic potential for new natural products, although many new biosynthetic gene clusters (BGCs) are silent. Therefore, efficient and stable genome modification techniques are needed to activate their production or to manipulate their biosynthesis towards increased production or improved properties.

Structural features of the bioactive cyanobacterium Nostoc sp. exopolysaccharide.

Microalgal biopolymers are studied mainly in terms of physico-chemical characterization, biological effects as well as possible biotechnological applications. Due to the significant antitussive, bronchodilator, anti-inflammatory and immunomodulatory effects of the previously isolated crude extracellular polysaccharide (EPS) produced by the cyanobacterium Nostoc sp., the purified biopolymer and its oligosaccharides, obtained after partial acid hydrolysis, were subjected to an in-depth NMR structural study.

Chlorella vulgaris α-L-arabino-α-L-rhamno-α,β-D-galactan structure and mechanisms of its anti-inflammatory and anti-remodelling effects.

Microalgal exopolysaccharides (EPSs) are given great attention due to their potential biotechnology applications. Purified C. vulgaris EPS was subjected to compositional and sugar linkage analyses, and partial acid hydrolysis.

Structural characteristics and biological effects of exopolysaccharide produced by cyanobacterium Nostoc sp.

Complex structure of cyanobacterium Nostoc sp. exopolysaccharide (EPS), with apparent molecular weight 214 × 10 g/mol, can be deduced from its composition. Chemical and NMR analyses found four dominant sugar monomers, namely (1 → 4)-linked α-l-arabinopyranose, β-d-glucopyranose, β-d-xylopyranose and (1 → 3)-linked β-d-mannopyranose, two different uronic acids and a lactyl group, with (1 → 4,6)-linked β-d-glucopyranose as the only branch point suggest a complex structure of this polymer.

A Structural Analysis of the Angucycline-Like Antibiotic Auricin from Subsp. CCM 3239 Revealed Its High Similarity to Griseusins.

We previously identified the gene cluster in subsp. CCM 3239 (formerly CCM 3239), which is responsible for the production of the angucycline-like antibiotic auricin (). Preliminary characterization of revealed that it possesses an aminodeoxyhexose d-forosamine and is active against Gram-positive bacteria.

The polyphenolic-polysaccharide complex of Agrimonia eupatoria L. as an indirect thrombin inhibitor - isolation and chemical characterization.

The polyphenolic-polysaccharide complex was isolated from the dried aerial parts of the medicinal plant Agrimonia eupatoria L. using a multi-step process involving the degreasing of the plant material by extraction with organic solvents, followed by extraction with hot alkali, neutralization, further separation with organic solvents and dialysis. The complex was homogeneous with a molecular weight of about 55 × 10 g/mol and consisted mainly of carbohydrates and polyphenols matrix, composed of lignin-related units, with the dominance of dimethoxyphenyl structures.

Influence of physicochemical properties of various soil types on iodide and iodate sorption.

Studies that deal with iodine mobility in uncontaminated agricultural soils are scarce and unique. Therefore, in this article, we have evaluated the sorption behavior of two most abundant naturally occurring inorganic iodine species - iodide and iodate - in several soil types. Our results showed that the sorption process is extremely slow with equilibrium achieved after ten days.

Chemico-physical and pharmacodynamic properties of extracellular Dictyosphaerium chlorelloides biopolymer.

Microalgae occupy all territories and their products represent a rich source of phytochemicals for human being. Green microalga Dictyosphaerium chlorelloides was found to be a significant producer of the extracellular biopolymer. Dominant components of the biopolymer were found to be Gal (39 wt%) with its methyl derivatives (15 wt%), Rha (19 wt%) and Man (14 wt%).

Impact of fliD and virulence plasmid pSEV on response of chicken embryo fibroblasts to Salmonella Enteritidis.

Salmonella Enteritidis is the main serovar of poultry origin in humans, but its complex interaction with certain avian cells is still not fully understood. Previously we identified several genes significantly induced in chicken embryo fibroblasts (CEFs) by the wild-type strain S. Enteritidis 11 (SE 11).