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. Since microorganisms play a vital role in controlling iodine cycling and fate in the environment, they also can be efficiently utilized in solving the issue of contamination spread. Thus, this paper summarizes all known on microbial processes that are involved in iodine transformation to highlight their prospects in remediation of the sites contaminated with radioactive iodine isotopes.

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. With the introduction of iodized table salt in the food industry, the thyroid status of the population has improved, but several areas remain iodine deficient. Furthermore, due to the strong relationship between iodine and selenium in metabolic processes, selenium deficiency often compromises the desired positive impact of salt iodization efforts. Therefore, a considerable number of studies have looked for alternative methods for the simultaneous supplementation of selenium and iodine in foodstuff. In most cases, the subject of these studies is crops; recently, meat has also been a subject of interest. This paper reviews the most recent strategies in agriculture to fortify selenium and iodine in crop plants, their effect on the quality of the plant species used, and the potential impact of food processing on their stability in fortified crops.

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. Since it can also mitigate the process of climate change, it is reasonable to study its biogeochemistry. Therefore, the aim of this review is to provide information on its origin, global fluxes and mechanisms of production in the environment.

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 Aspergillus niger for three weeks. This common soil fungus has shown exceptional ability to alter the distribution and mobility of selenium in the presence of both solid phases. The fungus initiated the extensive bioextraction of selenium from the surfaces of amorphous ferric oxyhydroxides, while the hausmannite (Mn₃O₄) was highly susceptible to biodeterioration in the presence of selenium. This resulted in specific outcomes regarding the selenium, iron, and manganese uptake by fungus and residual selenium concentrations in mineral phases as well. The adverse effects of bioleaching on fungal growth are also discussed.

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. Since the association of selenium with precipitates surfaces has been proven to be weak, the mineralogy of the system was affected insignificantly, and the goethite was identified as an only ferric phase in all treatments. However, the morphology and the crystallinity of ferric oxyhydroxides was slightly altered. Selenium affected the structural order of precipitates, especially at the initial phase of co-precipitation. Still, the crystal integrity and homogeneity increased with time almost constantly, regardless of the treatment. The thermal transformation into well crystalized hematite was more pronounced in the presence of selenite, while selenate-treated and selenium-free samples indicated the presence of highly disordered fraction. This highlights that the aftermath of selenium release does not result in destabilization of ferric phases; however, since weak interactions of selenium are dominant at alkaline conditions with goethite's surfaces, it still poses a high risk for the environment. The findings of this study should be applicable in waters affected by mining and metallurgical operations.

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. The sorption of both iodine species is well described by Freundlich isotherm. The affinity of iodine for all investigated soils in the observed concentration range is relatively low. Our results showed that besides iodine speciation, sorption efficiency is highly dependent on soil types and their characteristics. While in mineral soils with low organic carbon content iodide sorption is dominant, organic rich soils are more favorable for iodate sorption. Organic carbon, clay content, pH and the abundance of iron, aluminum and manganese oxides and hydroxides showed to be the most important soil properties controlling iodine sorption. Our results provide new insight into the complex iodine behavior and retention in soils. This is crucial for better understanding of iodine mobility and the ability to enter the food chain.

An extracellular galactoxylomannan of acapsular Cryptococcus laurentii mutant

An extracellular galactoxylomannan (GalXM) composed of D-Gal (34.0%), D-Xyl (26.6%) and D-Man (31.0%), and a small amount of L-Ara (4.0%) and D-Glc (4.4%) has been isolated from culture medium of acapsulated mutant of Cryptococcus laurentii by ethanol precipitation and gel filtration. Phosphorylated polymer of Mw approximately 75,000 contained 90% carbohydrates, 3.9% phosphorus and 5.3% proteins. Results of chemical and spectroscopic studies showed a highly branched structure of GalXM with a 1,6-linked mannopyranosyl-galactopyranosyl backbone (approximately 44%) branched predominantly at C-2 and C-3 of mannosyl, and C-3 of galactosyl residues by side chains terminated mainly by xylosyl and mannosyl residues, and to a less extent by arabinosyl and glucosyl ones.

[The relation of GERD, bronchial asthma and the upper respiratory tract]

Gastroesophageal reflux disease (GERD) is one of the most common diseases affecting upper gastrointestinal tract. It is a chronic disease, whith stadily growing incidence and prevalence in west countries during last 30 years. GERD is caused by pathologic gastroesophageal reflux (GER). GERD includes endoscopically positive, endoscopically negative and extraesophageal reflux disease. Extraesophageal symptoms of GERD have been of a growing attention and discussion during last few years. The most discussed topics are the relation of GERD and bronchial asthma (BA), chronic cough and symptomatology from ear, nose and throught (ENT) regions, but also non - cardial chest pain and many others.

AIM

In our clinic we ran a 5 years study which aim was to evaluate the presence of GERD in patients with bronchial asthma, chronic cough and affections from ENT regions. To assess if 3 months GERD treatment would improve lung function, subjective complaints (cough) and GERD control in asthmatics; if this treatment would allow to step - down with antiasthma medication. To assess if 3 months GERD treatment can improve objective and subjective assessments in patients with chronic cough and findings in ENT regions. As for GERD, we evaluated the improvement of pH and subjective complaints (pyrosis).

METHODS

We examined 86 patients with different severity of bronchial asthma, 54 patients with chronic cough and 31 patients with ENT symptoms. All patients underwent 24 hour esophageal pH metry, spirometry with lung function evaluation and objective ENT examination by flexible laryngoscopy. In case of pathologic finding on 24 hour pH-metry 3 months full antireflux treatment with proton pump inhibitors (PPI) and prokinetics was introduced. After 3 months of GERD treatment we performed control 24 hour esophageal pH metry, control spirometry and ENT examination by flexible laryngoscopy. Patients were asked to make their subjective symptoms assessments.

RESULTS

We found that GERD prevalence in patients with respiratory symptoms was very high. Three months GERD treatment improved lung function (FEV1) with statistical significance (p = 0.0319), and so improved GERD control (in 60.7% of patients with high statistical significance p = 0.0009). Subjective complaints (cough) also improved in most patients. 3 months GERD treatment did not allow to step down with maintenance BA therapy according to GINA guidelines, but it enabled to decrease the rescue medications in 50% of patients. Patients with chronic cough can benefit from GERD treatment as cough improved in 75.8% of patients.

CONCLUSION

Objective findings as well as subjective complaints improved in 75% of patients with ENT symptomatology. GERD control (DeMeester score and pyrosis if present) was highly statistically significant in all three groups of patients. It is necessary to mention, that there is a high presence of nocturnal acid breakthrough (NAB) in patients with respiratory symptoms: 30.3 % in patients with bronchial asthma, 63.6 % in patients with chronic cough and 45 % of patients with ENT manifestations.

(4-O-Methyl-alpha-D-glucurono)-D-xylan from Rudbeckia fulgida, var. sullivantii (Boynton et Beadle)

From the medicinal plant Rudbeckia fulgida, var. sillivantii (Boynton et Beadle) a low-molecular-mass (4-O-methyl-alpha-D-glucurono)-D-xylan was isolated by alkaline extraction, followed by ethanol precipitation, ion-exchange chromatography and gel filtration. The results of compositional and linkage analyses, supported by those of 1H and 13C NMR measurements of oligomers generated on partial acid hydrolysis, showed the (1-->4)-linked beta-D-xylopyranosyl backbone with about 18% of 4-O-methyl-D-glucuronic acid attached to O-2 of the xylose residues. From the mean distance of adjacent carboxyl groups, obtained from experimentally determined single-ion activity coefficients of calcium counterions, it followed that the uronic acid units are separated and distributed regularly along the xylan chain, i.e. approximately each sixth D-xylose unit bears a 4-O-methyl-D-glucuronic acid residue.

A nitro sugar derivative route to 2-thioepisophorose and 2-thiosophorose and their remarkable facile epimerization

The addition of 1-thio-D-glucose sodium salt to per-O-acetylated 1,2-dideoxy-1-nitro-D-arabino-hex-1-enitol, readily available from D-arabinose, afforded the corresponding 2-S-glycosylated 1-deoxy-1-nitro-D-mannitol and -D-glucitol peracetates. These, after deacetylation, were transformed by the Nef reaction to 2-thioepisophorose and 2-thiosophorose, respectively. The 2-thiodisaccharides easily epimerize in aqueous sodium bicarbonate at ambient temperature to a 1:4 equilibrium mixture. The predominant 2-thiosophorose was obtained crystalline. A 1H NMR study of the epimerization in deuterium oxide showed that the reaction involves an H-2 proton exchange mechanism.

NMR analysis of succinoglycans from different microbial sources: partial assignment of their 1H and 13C NMR spectra and location of the succinate and the acetate groups

In order to obtain information on the location of succinate and acetate groups, comparative NMR analyses were carried out on succinoglycans from different microbial sources by using conventional and advanced NMR techniques. In particular, one-dimensional, 1H and 13C NMR spectra were recorded for qualitative and quantitative analysis on native high-molecular-weight succinoglycans (both in the Na+ salt and free-acid forms) from Pseudomonas sp. NCIB 11592, Agrobacterium radiobacter A201-25, Rhizobium meliloti YE-2, and Rhizobium sp. isolated from Vicia faba and compared with those of the deacylated and deacylated-depyruvated, partially depolymerised exopolysaccharides from Rhizobium meliloti YE-2. Moreover, a series of two-dimensional experiments was performed on all the exopolysaccharides aiming at the partial assignment of the NMR spectra. The NMR data showed that succinate is located on O-6 of either one or both of the two side chain 3-linked beta-D-Glc residues, whereas the acetate (when it is present) is located on one of the O-6 of backbone 4-linked beta-D-Glc units, but the specific site could not be determined. In addition, the spectral features of the succinate substituent were found to be sensitive to pH changes.

Immobilisation of beta-D-galactosidase from Escherichia coli on cellulose beads and its use for the synthesis of disaccharide derivatives

beta-D-Galactosidase, isolated from cloned E. coli, was immobilised on cellulose beads via oxidation with sodium periodate, activation by cyanuric chloride, or diazotisation. beta-D-Galactosidase immobilised via azo bonds showed the highest relative activity and thermostability, and was used for synthesis of disaccharide methyl glycosides.

Antimicrobial effect of 4-nitrophenylhydrazones, isonicotinoylhydrazones and N-4-nitrophenylglycosylamines of D- and L-aldoses

The antibacterial effect of 19 4-nitrophenylhydrazones, isonicotinoylhydrazones, and N-4-nitrophenylhydrazones, of 9 mono- and 2 disaccharides was tested with Micrococcus luteus, Bacillus licheniformis and Escherichia coli.