Presence Of High Iron Concentrations Research Articles

Role of transcriptomic and genomic analyses in improving the comprehension of cefiderocol activity in Acinetobacter baumannii.

The mechanisms of action and resistance of cefiderocol (FDC) in Acinetobacter baumannii are still not fully elucidated, but iron transport systems have been evoked in its entry into the cell to reach the penicillin-binding proteins (PBPs). To capture the dynamics of gene expression related to FDC action in various conditions, we report on the genomic and transcriptomic features of seven A. baumannii strains with different FDC susceptibility, focusing on the variants in genes associated with β-lactam resistance and the expression of the siderophore biosynthesis and transport systems acinetobactin and baumannoferrin. We also investigated the expression of the TonB energy transduction system (ETS) and siderophore receptors piuA and pirA. The four clinical samples belonged to the same clonal complex (CC2), and the two strains with the highest FDC MICs showed peculiar variants in PBP2 and ampC. Similarly, the two clinical strains with the lowest MICs shared variants in an outer membrane protein as well as ampC. Gene expression analyses highlighted the up-regulation of the acinetobactin and baumannoferrin genes in response to iron depletion and a down-regulation in the presence of high iron concentrations. In response to FDC, gene expression seemed strain-dependent, probably due to the different metabolic features of each strain. Overall, FDC activates the ETS, confirming the active import of the drug; baumannoferrin, more than acinetobactin, appeared stimulated by FDC in an iron-depleted medium. In conclusion, iron transport systems play a clear role in the FDC uptake, and their expression likely contributes to MIC variation together with β-lactam resistance determinants.IMPORTANCEAcinetobacter baumannii poses a threat to healthcare due to its ability to give difficult-to-treat infections as a consequence of our shortage of antibiotic molecules active on this multidrug-resistant bacterium. Cefiderocol (FDC) represents one of the few drugs active on A. baumannii, and to preserve its activity, this study explored the transcriptomic and genomic features of seven strains with varying susceptibility to FDC. Transcriptomic analyses revealed the different effects of FDC on iron transport systems, promoting mainly baumannoferrin expression-thus more likely related to FDC entry-and the energy transduction systems. These findings suggest that not all iron transport systems are equally involved in FDC entry into A. baumannii cells. Finally, mutations in PBPs and β-lactamases may contribute to the resistance onset. Overall, the study sheds light on the importance of iron availability and metabolic differences in FDC resistance, offering insights into understanding the evolution of resistance in A. baumannii strains.

Application of total reflection X-Ray fluorescence spectrometry to quantify cobalt concentration in the presence of high iron concentration in biogas plants

The concentration of iron is usually several times higher than of cobalt in many environmental samples. Total Reflection X-ray Fluorescence Spectrometry can be used for monitoring in the ppb range, due to its high sensitivity and rapid multi elemental analysis capability. Unfortunately, cobalt/iron-spectra exhibit interference, because the energy line of iron (Kβ) overlaps the energy line of cobalt (Kα). As a result, the concentration of cobalt measured usually appears to be lower than the actual concentration or even below detection limit. In this study, application of dispersive liquid-liquid micro-extraction procedure was used to selectively extract iron in order to enable accurate cobalt determination. The volume of hydrochloric acid, volume of ethyl ether, number of stages of extraction and the duration of extraction were considered with the purpose of obtaining elaborated optimum extraction conditions. The sensitivity and linearity of the method were determined using liquid and solid samples through spike experiments. This new procedure was successfully applied to slurries of biogas plants having total solids content in the range of 7–12%. It was possible to estimate dissolved cobalt concentration of 50 µg L−1 in the presence of 4000-fold iron concentration. Also, recoveries of between 75–84% was obtained after spiking 10–20 µg L−1 of cobalt, whiles recoveries of above 94% were obtained after spiking cobalt concentrations >20 µg L−1 after application of the procedure.

Rare Earth Element (REE)-Dependent Growth of Pseudomonas putida KT2440 Relies on the ABC-Transporter PedA1A2BC and Is Influenced by Iron Availability.

In the soil-dwelling organism Pseudomonas putida KT2440, the rare earth element (REE)-utilizing, and pyrroloquinoline quinone (PQQ)-dependent ethanol dehydrogenase PedH is part of a periplasmic oxidation system that is vital for growth on various alcoholic volatiles. Production of PedH and its Ca2+-dependent counterpart PedE is inversely regulated in response to lanthanide (Ln3+) bioavailability, a mechanism termed the REE-switch. In the present study, we demonstrate that copper, zinc, and in particular, iron availability influences this regulation in a pyoverdine-independent manner by increasing the minimal Ln3+ concentration required for the REE-switch to occur by several orders of magnitude. A combined genetic and physiological approach reveals that an ABC-type transporter system encoded by the gene cluster pedA1A2BC is essential for efficient growth on 2-phenylethanol with low (nanomolar) Ln3+ concentrations. In the absence of pedA1A2BC, a ∼100-fold higher La3+-concentration is needed for PedH-dependent growth but not for the ability to repress growth based on PedE activity. From these results, we conclude that cytoplasmic uptake of lanthanides through PedA1A2BC is essential to facilitate REE-dependent growth on 2-phenylethanol under environmental conditions with poor REE bioavailability. Our data further suggest that the La3+/Fe2+/3+ ratio impacts the REE-switch through the mismetallation of putative La3+-binding proteins, such as the sensor histidine kinase PedS2, in the presence of high iron concentrations. As such, this study provides an example for the complexity of bacteria-metal interactions and highlights the importance of medium compositions when studying physiological traits in vitro in particular in regard to REE-dependent phenomena.

Isolation of Iron Bacteria from Washing Sludge Filters Kolda (Senegal) Water Treatment Station and Study of the Kinetics of Biological Degradation of the Iron (II)

In the present work, the treatment of synthetic waters doped with iron (II) has been studied. The treatment mechanism used in this study is the biological oxidation which consists, in test tubes, of bringing bacteria isolated on Petri dishes into contact with water containing divalent iron (II). These de-ironing bacteria (non-specific bacteria) are used to carry out laboratory biological oxidation experiments on iron (II) under different pH conditions (pH = 3.4 - 3.6, pH = 7.3 - 7.5 and pH = 9.8 - 10) and variable concentration of iron (II). Biological treatment trials included different concentrations of iron during time intervals of a day. Examination of the elimination kinetics of Iron (II) indicates a removal rate of 59.453% for an initial iron concentration in the synthetic solution of 1 mg·L−1 at basic pH (pH = 9.8 - 10). Therefore, the degradation of divalent iron by this method seems to be quite effective, but it should be noted that biological nitrification is impaired by the presence of high iron concentrations above 5 mg·L−1.

Iron contamination in the waters of Upper Yamuna basin

The alluvial plains of Upper Yamuna basin covers a vast area of around 11,500sq. km. It has been reported that extensive agriculture and urbanization has led to release of various contaminants in river as well as groundwater system in the study area. Iron concentration in water has its bearing on human health. Presence of high Iron concentration has been reported from parts of basin in NCR Delhi. In this perspective the article highlights the spatial distribution of Iron in surface and groundwater system of the upper Yamuna basin. It also tries to assess the link between iron contaminations in groundwater as well as river water with other contaminants to identify their sources. The article has revealed that even though the flood plain sediments have significant presence of iron rich minerals, the anomalous enrichment of iron in both surface and groundwater is linked to anthropogenic sources.

The influence of iron on the proteomic profile of Chromobacterium violaceum.

Background Chromobacterium violaceum is a bacterium commonly found in tropical and subtropical regions and is associated with important pharmacological and industrial attributes such as producing substances with therapeutic properties and synthesizing biodegradable polymers. Its genome was sequenced, however, approximately 40% of its genes still remain with unknown functions. Although C. violaceum is known by its versatile capacity of living in a wide range of environments, little is known on how it achieves such success. Here, we investigated the proteomic profile of C. violaceum cultivated in the absence and presence of high iron concentration, describing some proteins of unknown function that might play an important role in iron homeostasis, amongst others.ResultsBriefly, C. violaceum was cultivated in the absence and in the presence of 9 mM of iron during four hours. Total proteins were identified by LC-MS and through the PatternLab pipeline. Our proteomic analysis indicates major changes in the energetic metabolism, and alterations in the synthesis of key transport and stress proteins. In addition, it may suggest the presence of a yet unidentified operon that could be related to oxidative stress, together with a set of other proteins with unknown function. The protein-protein interaction network also pinpointed the importance of energetic metabolism proteins to the acclimatation of C. violaceum in high concentration of iron.ConclusionsThis is the first proteomic analysis of the opportunistic pathogen C. violaceum in the presence of high iron concentration. Our data allowed us to identify a yet undescribed operon that might have a role in oxidative stress defense. Our work provides new data that will contribute to understand how this bacterium achieve its capacity of surviving in harsh conditions as well as to open a way to explore the yet little availed biotechnological characteristics of this bacterium with the further exploring of the proteins of unknown function that we showed to be up-regulated in high iron concentration.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-014-0267-6) contains supplementary material, which is available to authorized users.

Modeling aluminum–silicon chemistries and application to Australian acidic playa lakes as analogues for Mars

Recent Mars missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major relevant findings are the presence in Meridiani Planum sediments of the mineral jarosite (a ferric sulfate salt) and related minerals that require formation from an acid–salt brine and oxidizing environment. Similar mineralogies have been observed in acidic saline lake sediments in Western Australia (WA), and these lakes have been proposed as analogues for acidic sedimentary environments on Mars. The prior version of the equilibrium chemical thermodynamic FREZCHEM model lacked Al and Si chemistries that are needed to appropriately model acidic aqueous geochemistries on Earth and Mars. The objectives of this work were to (1) add Al and Si chemistries to the FREZCHEM model, (2) extend these chemistries to low temperatures (<0 °C), if possible, and (3) use the reformulated model to investigate parallels in the mineral precipitation behavior of acidic Australian lakes and hypothetical Martian brines. FREZCHEM is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions using the Pitzer approach for the temperature range from <−70 to 25 °C and the pressure range from 1 to 1000 bars. Aluminum chloride and sulfate mineral parameterizations were based on experimental data. Aluminum hydroxide and silicon mineral parameterizations were based on Gibbs free energy and enthalpy data. New aluminum and silicon parameterizations added 12 new aluminum/silicon minerals to this Na–K–Mg–Ca–Fe(II)–Fe(III)–Al–H–Cl–Br–SO 4–NO 3–OH–HCO 3–CO 3–CO 2–O 2–CH 4–Si–H 2O system that now contain 95 solid phases. There were similarities, differences, and uncertainties between Australian acidic, saline playa lakes and waters that likely led to the Burns formation salt accumulations on Mars. Both systems are similar in that they are dominated by (1) acidic, saline ground waters and sediments, (2) Ca and/or Mg sulfates, and (3) iron precipitates such as jarosite and hematite. Differences include: (1) the dominance of NaCl in many WA lakes, versus the dominance of Fe–Mg–Ca–SO 4 in Meridiani Planum, (2) excessively low K + concentrations in Meridiani Planum due to jarosite precipitation, (3) higher acid production in the presence of high iron concentrations in Meridiani Planum, and probably lower rates of acid neutralization and hence, higher acidities on Mars owing to colder temperatures, and (4) lateral salt patterns in WA lakes. The WA playa lakes display significant lateral variations in mineralogy and water chemistry over short distances, reflecting the interaction of acid ground waters with neutral to alkaline lake waters derived from ponded surface runoff. Meridiani Planum observations indicate that such lateral variations are much less pronounced, pointing to the dominant influence of ground water chemistry, vertical ground water movements, and aeolian processes on the Martian surface mineralogy.

Microaspersores entupidos devido a problemas de ferro na água

Um dos aspectos relevantes a ser considerado no manejo da irrigação é a uniformidade de distribuição de água pelo sistema. Este trabalho foi desenvolvido com o objetivo de avaliar a eficiência da cloração com a utilização de hipoclorito de sódio na desobstrução de microaspersores devido à utilização de águas com elevado teor de ferro. Um sistema com dez meses de uso apresentava setores com vazões de 5% a 57% menores que a vazão de projeto. Foi feito o tratamento químico da água de irrigação, utilizando-se hipoclorito de sódio com 12% de cloro livre na dosagem de 100 mg L-1 e ácido sulfúrico, na concentração de 98%, para manter o pH da água de irrigação em torno de 4,5. O resultado indicou que houve aumento significativo nas vazões médias dos microaspersores em todos os setores avaliados e diminuição na variação da vazão dos mesmos com relação à estimada no projeto.

Identification of iron-regulated proteins ofMycobacterium tuberculosisand cloning of tandem genes encoding a low iron-induced protein and a metal transporting ATPase with similarities to two-component metal transport systems

Iron plays a central role in the pathogenesis ofMycobacterium tuberculosis, the principal causative agent of tuberculosis. To learn more about iron acquisition by this bacterium, its iron regulated proteins (IRPs) were investigated. Seven IRPs were identified — three increased by high iron concentrations, and four by low iron concentrations. The smallest protein induced by low iron, Irp10, is tightly iron regulated as it is virtually absent in bacteria cultured in the presence of high iron concentrations. The gene (irpA) encoding this protein and an adjacent open reading frame,mtaA, were cloned and sequenced. The protein encoded bymtaA(Mta72) has striking homology to metal transporting P-type ATPases. This study suggests that Irp10 and Mta72 function as a two-component metal transport system inM. tuberculosis.

Mercury and Iron Uptake by Cytosomes in Mantle Epithelial Cells of Quahog Clams (Mercenaria mercenaria) Exposed to Mercury

Specimens of the quahog clam Mercenaria mercenaria were placed in sea water containing mercury (Hg++) concentrations of 0.1, 1,and 10 parts per million (ppm) for 6 days. A dose-related increase of electron dense cytosomes was observed by electron microscopy in mantle tentacle epithelial cells of mercury-treated clams. Energy dispersive X-ray microanalysis of these cytosomes disclosed the presence of high iron concentrations in relation to mercury. Analysis of mantle fringes from the same clams by atomic absorption spectroscopy showed marked changes in tissue iron levels of mercury-treated clams in comparison to controls.

Quantitative biochemical and microspectrophotometric feulgen DNA analyses on Tetrahymena cells treated with iron

It has been found that Feulgen staining of the macronuclei of Tetrahymena pyriformis cells, treated with iron after fixation or grown in the presence of high iron concentrations, was depressed from 32 to 46 per cent of that of control cells. Biochemical DNA analyses on aliquots of the same cell populations showed no significant differences in the amount of DNA per cell.