Iron-rich Environments Research Articles

Enhanced CRC Growth in Iron-Rich Environment, Facts and Speculations.

The contribution of nutritional factors to disease development has been demonstrated for several chronic conditions including obesity, type 2 diabetes, metabolic syndrome, and about 30 percent of cancers. Nutrients include macronutrients and micronutrients, which are required in large and trace quantities, respectively. Macronutrients, which include protein, carbohydrates, and lipids, are mainly involved in energy production and biomolecule synthesis; micronutrients include vitamins and minerals, which are mainly involved in immune functions, enzymatic reactions, blood clotting, and gene transcription. Among the numerous micronutrients potentially involved in disease development, the present review will focus on iron and its relation to tumor development. Recent advances in the understanding of iron-related proteins accumulating in the tumor microenvironment shed light on the pivotal role of iron availability in sustaining pathological tumor hallmarks, including cell cycle regulation, angiogenesis, and metastasis.

Production of iron-enriched yeast and it’s application in the treatment of iron-deficiency anemia

Iron deficiency anemia (IDA) is one of the most serious forms of malnutrition. Wild type strains of Saccharomyces cerevisiae have higher tolerance to inorganic iron and higher iron conversion and accumulation capacity. The aim of this study was to investigate the effect of S. cerevisiae enriched iron as a potential organic iron supplement on mice with iron deficiency anemia. 60 male Kunming mice (KM mice, with strong adaptability and high reproduction rate, it can be widely used in pharmacology, toxicology, microbiology and other research) were randomly divided into normal control group and iron deficiency diet model group to establish IDA model. After the model was established, IDA mice were randomly divided into 5 groups: normal control group, IDA group, organic iron group (ferrous glycinate), inorganic iron group (ferrous sulfate) and S. cerevisiae enriched iron group. Mice in the experimental group were given different kinds of iron by intragastric administration once a day for 4w. The results showed that S. cerevisiae enriched iron had an effective recovery function, and the body weight and hematological parameters of IDA mice returned to normal levels. The activities of superoxide dismutase, glutathione peroxidase and total antioxidant capacity in serum were increased. In addition, the strain no. F8, able to grow in an iron-rich environment, was more effective in alleviating IDA and improving organ indices with fewer side effects compared to ferrous glycinate and ferrous sulfate groups. This study suggests that the iron-rich strain no. F8 may play an important role in improving IDA mice and may be developed as a new iron supplement.

The dual roles of dissimilatory iron reduction in the carbon cycle: The "iron mesh" effect can increase inorganic carbon sequestration.

Dissimilatory iron reduction (DIR) can drive the release of organic carbon (OC) as carbon dioxide (CO2 ) by mediating electron transfer between organic compounds and microbes. However, DIR is also crucial for carbon sequestration, which can affect inorganic-carbon redistribution via iron abiotic-phase transformation. The formation conditions of modern carbonate-bearing iron minerals (ICFe ) and their potential as a CO2 sink are still unclear. A natural environment with modern ICFe , such as karst lake sediment, could be a good analog to explore the regulation of microbial iron reduction and sequential mineral formation. We find that high porosity is conducive to electron transport and dissimilatory iron-reducing bacteria activity, which can increase the iron reduction rate. The iron-rich environment with high calcium and OC can form a large sediment pore structure to support rapid DIR, which is conducive to the formation and growth of ICFe . Our results further demonstrate that the minimum DIR threshold suitable for ICFe formation is 6.65 μmol g-1 dw day-1 . DIR is the dominant pathway (average 66.93%) of organic anaerobic mineralization, and the abiotic-phase transformation of Fe2+ reduces CO2 emissions by ~41.79%. Our findings indicate that as part of the carbon cycle, DIR not only drives mineralization reactions but also traps carbon, increasing the stability of carbon sinks. Considering the wide geographic distribution of DIR and ICFe , our findings suggest that the "iron mesh" effect may become an increasingly important vector of carbon sequestration.

Plasmodium yoelii iron transporter PyDMT1 interacts with host ferritin and is required in full activity for malarial pathogenesis

BackgroundThe rapid reproduction of malaria parasites requires proper iron uptake. However, the process of iron absorption by parasites is rarely studied. Divalent metal transporter (DMT1) is a critical iron transporter responsible for uptaking iron. A homolog of human DMT1 exists in the malaria parasite genome, which in Plasmodium yoelii is hereafter named PyDMT1.ResultsPyDMT1 knockout appears to be lethal. Surprisingly, despite dwelling in an iron-rich environment, the parasite cannot afford to lose even partial expression of PyDMT1; PyDMT1 hypomorphs were associated with severe growth defects and quick loss of pathogenicity. Iron supplementation could completely suppress the defect of the PyDMT1 hypomorph during in vitro culturing. Genetic manipulation through host ferritin (Fth1) knockout to increase intracellular iron levels enforced significant growth inhibition in vivo on the normal parasites but not the mutant. In vitro culturing with isolated ferritin knockout mouse erythrocytes completely rescued PyDMT1-hypomorph parasites.ConclusionA critical iron requirement of malaria parasites at the blood stage as mediated by this newly identified iron importer PyDMT1, and the iron homeostasis in malarial parasites is finely tuned. Tipping the iron balance between the parasite and host will efficiently kill the pathogenicity of the parasite. Lastly, PyDMT1 hypomorph parasites were less sensitive to the action of artemisinin.

Iron affects the sphere-forming ability of ovarian cancer cells in non-adherent culture conditions.

Introduction: Detachment from the extracellular matrix (ECM) is the first step of the metastatic cascade. It is a regulated process involving interaction between tumor cells and tumor microenvironment (TME). Iron is a key micronutrient within the TME. Here, we explored the role of iron in the ability of ovarian cancer cells to successfully detach from the ECM. Methods: HEY and PEO1 ovarian cancer cells were grown in 3D conditions. To mimic an iron rich TME, culture media were supplemented with 100μM Fe3+. Cell mortality was evaluated by cytofluorimetric assay. The invasive potential of tumor spheroids was performed in Matrigel and documented with images and time-lapses. Iron metabolism was assessed by analyzing the expression of CD71 and FtH1, and by quantifying the intracellular labile iron pool (LIP) through Calcein-AM cytofluorimetric assay. Ferroptosis was assessed by quantifying mitochondrial reactive oxygen species (ROS) and lipid peroxidation through MitoSOX and BODIPY-C11 cytofluorimetric assays, respectively. Ferroptosis markers GPX4 and VDAC2 were measured by Western blot. FtH1 knockdown was performed by using siRNA. Results: To generate spheroids, HEY and PEO1 cells prevent LIP accumulation by upregulating FtH1. 3D HEY moderately increases FtH1, and LIP is only slightly reduced. 3D PEO1upregulate FtH1 and LIP results significantly diminished. HEY tumor spheroids prevent iron import downregulating CD71, while PEO1 cells strongly enhance it. Intracellular ROS drop down during the 2D to 3D transition in both cell lines, but more significantly in PEO1 cells. Upon iron supplementation, PEO1 cells continue to enhance CD71 and FtH1 without accumulating the LIP and ROS and do not undergo ferroptosis. HEY, instead, accumulate LIP, undergo ferroptosis and attenuate their sphere-forming ability and invasiveness. FtH1 knockdown significantly reduces the generation of PEO1 tumor spheroids, although without sensitizing them to ferroptosis. Discussion: Iron metabolism reprogramming is a key event in the tumor spheroid generation of ovarian cancer cells. An iron-rich environment impairs the sphere-forming ability and causes cell death only in ferroptosis sensitive cells. A better understanding of ferroptosis sensitivity could be useful to develop effective treatments to kill ECM-detached ovarian cancer cells.

Genomic Approaches and Analyses of Slow-Growing Obligate Iron-Metabolizing Microbes

The biogeochemical cycling of iron is a vastly important process that has been a major factor defining life on Earth both before and after the Great Oxidation Event. While both abiotic and biotic factors contributing to the iron cycle have been studied for many years, the bulk of studies on iron metabolizing organisms has focused on a select few, easily manipulated model organisms. Recent discoveries have identified several unique and difficult to work with organisms from iron rich environments that survive solely on iron as either an electron acceptor or donor. The Fe(III)-reducing, Gram-positive Firmicute Metallumcola ferriviriculae MK1 was recently isolated from the Soudan Underground Mine in northern Minnesota from brine waters that intersect 2.7 Ga banded iron formations within the Canadian Shield. M. ferriviriculae MK1, which grows anaerobically using Fe(III)-citrate as its sole electron acceptor, is also mesophilic, spore-forming, culturable, and rich in multiheme cytochromes. Multiheme cytochromes are a well-established mechanism for Fe(III) reduction among the model Gram-negative microbes, such as Shewanella oneidensis and Geobacter sulfurreducens, but is poorly studied in Gram-positives. While the slow growth times of M. ferriviriculae MK1 make it difficult to study in the laboratory, the genome encodes homologs to multiheme cytochromes utilized by G. sulfurreducens for Fe(III) reduction. Specifically, two gene clusters (MK1_2258-2259 and MK1_2264-2265) each encode proteins homologous to the b-type cytochrome domain (60% and 61% sequence similarity, respectively) and c-type cytochrome domain (44.9% and 47.14%, respectively) of cbcL, which is used for reduction of mid-range redox potential acceptors in G. sulfurreducens and MK1_1670 is homologous to imcH (54.3% sequence similarity), which is used for higher redox potential acceptors. Additionally, the MK1 genome contains genes associated with sporulation, including genes encoding the master sporulation regulator spo0A, the peptidoglycan remodeling enzymes spoIID, spoIIP, and spoIIM, the spore morphogenesis protein spoIVA, and the small, acid-soluble spore proteins sspA, sspB, sspC, sspD, and sspF. Extraction and isolation of MK1 spores will facilitate evaluation of sporulation and germination conditions to shed light on a crucial preservation mechanism from an organism found in an environment with limited nutrients. Further evaluation into this novel organism can also give us insights into the microbial impacts on the iron cycle in the deep terrestrial biosphere. Another microbe of interest that was isolated from an iron-rich environment is the obligate Fe(II)-oxidizing Mariprofundus ferrooxydans PV-1, which was enriched from iron-rich mats associated with hydrothermal vents at the Kama’ehuakanaloa Seamount (previously Lo’ihi) in Hawaii. M. ferrooxydans PV-1 is a stalk-forming Fe(II)-oxidizing microbe and the first Zetaproteobacterium characterized. While M. ferrooxydans PV-1 can reliably be grown (doubling time of ~12 hours) in liquid medium traditional genetic methods are challenging because it does not make colonies on agar plates. To identify essential and non-essential genes, we developed a conjugation method using E. coli and successfully generated a transposon library in M. ferrooxydans. Libraries were grown under kanamycin selection with Fe(II)-chloride as the sole electron donor and samples isolated for analysis at two different timepoints. Deep sequencing of the mutant population at these timepoints was performed and the reads were mapped back to the M. ferrooxydans PV-1 genome to identify transposon insertion sites. Initial evaluation of the reads has identified 31 transposon insertion sites found within both the first- and second-generation populations, with 21 hits representing stable insertions in non-essential genes, including a predicted malate dehydrogenase (SPV1_772) and a predicted phospholipase (SPV1_8286), that may be useful future targets for gene insertion sites. Further evaluation comparing the read depth between the generations should identify genes that were selected for or against during the subculturing. These studies and approaches are providing insights into the roles these challenging, non-model organisms are performing in iron-rich environments, which provides a better context for the biogeochemical cycling of iron in relevant biospheres.

Dissolved carbon in biochar: Exploring its chemistry, iron complexing capability, toxicity in natural redox environment

Dissolved black carbon (DBC) plays a crucial role in the migration and bioavailability of iron in water. However, the properties of DBC releasing under diverse pyrolysis conditions and dissolving processes have not been systematically studied. Here, the compositions of DBC released from biochar through redox processes dominated by bacteria and light were thoroughly studied. It was found that the DBC released from straw biochar possess more oxygen-containing functional groups and aromatic substances. The content of phenolic and carboxylic groups in DBC was increased under influence of microorganisms and light, respectively. The concentration of phenolic hydroxyl groups increased from 10.0∼57.5 mmol/gC to 6.6 ∼65.2 mmol/gC, and the concentration of carboxyl groups increased from 49.7∼97.5 mmol/gC to 62.1 ∼113.3 mmol/gC. Then the impacts of DBC on pyrite dissolution and microalgae growth were also investigated. The complexing Fe3+ was proved to play a predominant role in the dissolution of ferrous mineral in DBC solution. Due to complexing between iron ion and DBC, the amount of dissolved Fe in aquatic water may rise as a result of elevated number of aromatic components with oxygen containing groups and low molecular weight generated under light conditions. Fe-DBC complexations in solution significantly promoted microalga growth, which might be attributed to the stimulating effect of dissolved Fe on the chlorophyll synthesis. The results of study will deepen our understanding of the behavior and ultimate destiny of DBC released into an iron-rich environment under redox conditions.

Biochemical characterization and mercury methylation capacity of Geobacter sulfurreducens biofilms grown in media containing iron hydroxide or fumarate

Geobacter species are common in iron-rich environments and can contribute to formation of methylmercury (MeHg), a neurotoxic compound with high bioaccumulation potential formed as a result of bacterial and archaeal physiological activity. Geobacter sulfurreducens can utilize various electron acceptors for growth including iron hydroxides or fumarate. However, it remains poorly understood how the growth on these compounds affects physiological properties of bacterial cells in biofilms, including the capacity to produce MeHg. The purpose of this study was to determine changes in the biochemical composition of G. sulfurreducens during biofilm cultivation in media containing iron hydroxide or fumarate, and to quantify mercury (Hg) methylation capacity of the formed biofilms. Biofilms were characterized by Fourier-transform infrared spectroscopy in the attenuated total reflection mode (ATR-FTIR), Resonance Raman spectroscopy and confocal laser scanning microscopy. MeHg formation was quantified by mass spectrometry after incubation of biofilms with 100 nM Hg. The results of ATR-FTIR experiments showed that in presence of fumarate, G. sulfurreducens biofilm formation was accompanied by variation in content of the energy-reserve polymer glycogen over time, which could be cancelled by the addition of supplementary nutrients (yeast extract). In contrast, biofilms cultivated on Fe(III) hydroxide did not accumulate glycogen. The ATR-FTIR results further suggested that Fe(III) hydroxide surfaces bind cells via phosphate and carboxylate groups of bacteria that form complexes with iron. Furthermore, biofilms grown on Fe(III) hydroxide had higher fraction of oxidized cytochromes and produced two to three times less biomass compared to conditions with fumarate. Normalized to biofilm volume, the content of MeHg was similar in assays with biofilms grown on Fe(III) hydroxide and on fumarate (with yeast extract and without). These results suggest that G. sulfurreducens biofilms produce MeHg irrespectively from glycogen content and cytochrome redox state in the cells, and warrant further investigation of the mechanisms controlling this process.

Dissolved organic matter accelerates microbial degradation of 17 alpha-ethinylestradiol in the presence of iron mineral

Dissolved organic matter (DOM) and iron minerals widely existing in the natural aquatic environment can mediate the migration and transformation of organic pollutants. However, the mechanism of interaction between DOM and iron minerals in the microbial degradation of pollutants deserves further investigation. In this study, the mechanism of 17 alpha-ethinylestradiol (EE2) biodegradation mediated by humic acid (HA) and three kinds of iron minerals (goethite, magnetite, and pyrite) was investigated. The results found that HA and iron minerals significantly accelerated the biodegradation process of EE2, and the highest degradation efficiency of EE2 (48%) was observed in the HA-mediated microbial system with pyrite under aerobic conditions. Furthermore, it had been demonstrated that hydroxyl radicals (HO•) was the main active substance responsible for the microbial degradation of EE2. HO• is primarily generated through the reaction between hydrogen peroxide secreted by microorganisms and Fe(II), with aerobic conditions being more conducive. The presence of iron minerals and HA could change the microbial communities in the EE2 biodegradation system. These findings provide new information for exploring the migration and transformation of pollutants by microorganisms in iron-rich environments.

Sub-inhibitory concentrations of ampicillin affect microbial Fe(III) oxide reduction

Antibiotics are ubiquitous in the iron-rich environments but their roles in microbial reduction of Fe(III) oxides are still unclear. Using ampicillin and Geobacter soli, this study investigated the underlying mechanism by which antibiotic regulated microbial reduction of Fe(III) oxides. Results showed that sub-minimal inhibitory concentrations (sub-MIC) of ampicillin significantly affected ferrihydrite reduction by G. soli, with a stimulatory effect at 1/64 and 1/32 MIC and an inhibitory effect at 1/8 MIC. Increasing ampicillin concentration resulted in increasing cell length and decreasing bacterial zeta potential that were beneficial for ferrihydrite reduction, and decreasing outer membrane permeability that was unfavorable for ferrihydrite reduction. The respiratory metabolism ability was enhanced by 1/64 and 1/32 MIC ampicillin and reduced by 1/8 MIC ampicillin, which was also responsible for regulation of ferrihydrite reduction by ampicillin. The ferrihydrite reduction showed a positive correlation with the redox activity of extracellular polymeric substances (EPS) which was tied to the cytochrome/polysaccharide ratio and the content of α-helices and β-sheet in EPS. These results suggested that ampicillin regulated microbial Fe(III) oxide reduction through modulating the bacterial morphology, metabolism activity and extracellular electron transfer ability. Our findings provide new insights into the environmental factors regulating biogeochemical cycling of iron.

Enterococcus faecalis thrives in dual-species biofilm models under iron-rich conditions.

Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) are pathogenic strains that often coexist in intestinal flora of humans and are prone to cause biofilm-associated infections, such as gastrointestinal tract and urinary tract infections. Earlier studies have demonstrated that E. faecalis biofilm can metabolize ferrous ions in iron-rich environments and promote biofilm growth under in-vivo conditions. However, the influence of iron transporters on dual-species biofilm growth and the nature of molecular-level interactions between iron transporter proteins and Fe2+ remains unknown. Therefore, in this work, co-culture studies were performed and the study indicates that Fe2+ at concentrations of 50-150µM promotes the colonization of E. coli, and Fe2+ concentrations of 50-200µM promote the growth of E. faecalis and dual-species colonies. Atomic absorption spectroscopy results reveal that Fe2+ ion augmentation in bacterial cells was increased to 4 folds in the single-species model and 11 folds in the dual-species model under iron-supplemented conditions. Furthermore, Fe2+ augmentation increased the antibiotic resistance of E. faecalis in both single- and dual-species bacterial cultures. In addition, in-silico docking were performed to determine a three-dimensional (3D) structure of ferrous iron-transporter proteins FeoB of E. faecalis and its affinity to extracellular Fe2+. Our model suggests that the FeoB facilitates the Fe2+ uptake in E. faecalis cells in the absence of iron chelator, 2,2-bipyridyl.

The role of magnetite (Fe3O4) particles for enhancing the performance and granulation of anammox

In this study, two lab-scale sequencing batch reactors each with an effective volume of 2.3 L were operated as C-AMX (no carrier addition) and M-AMX (magnetite carrier added) for 147 days with synthetic wastewater at an NLR range of 0.19–0.47 kgN/m3/d. The long-term effect of magnetite on the granulation and performance of anammox bacteria in terms of nitrogen removal and other essential parameters were confirmed. In phase I (1–24 days), M-AMX took approximately 12 days to obtain a nitrogen removal rate (NRR) above 80 % of the initial input nitrogen. Although free nitrous acid inhibited the reactor at a high concentration at the onset of phase III, the NRR of M-AMX recovered about 3.7 times faster than that of C-AMX. In addition, it was confirmed that the M-AMX granules had a dense and compact structure compared to C-AMX, and the presence of the carrier promoted the development of these resilient granules. While the measured microbial stress gradually increased in C-AMX reactor, a vice versa was observed in the M-AMX reactor as granulation proceeded. Compared to other alternative iron-based carrier particles, the stable crystal structure of magnetite as a carrier created a mechanism where filamentous bacteria groups were repelled from the granulation hence the microbial stress in the M-AMX in the final phase was 61.54 % lower than that in the C-AMX. The iron rich environment created by the magnetite addition led to Ignavibacteria, (a Feammox bacteria) increasing significantly in the M-AMX bioreactor.

Iron deficient diets modify the gut microbiome and reduce the severity of enteric infection in a mouse model of S. Typhimurium-induced enterocolitis

Enteric infections are widespread in infants and children living in low-resource settings. Iron availability in the gastrointestinal tract may modify the gut microbiome and impact the incidence and severity of enteropathy. This study was designed to determine the effect of an iron-deplete compared to an iron-rich environment in the lower intestine on the gut microbiome, and whether iron availability in the lower intestine affects the host immune response and severity of enteric infection in young mice. Weanling C57BL/6 female mice were fed an iron deficient (Fe−, <6 ppm iron) or an iron fortified (Fe+, 300 ppm iron) diet for 6 weeks. Mice were pretreated with streptomycin prior to oral inoculation of Salmonella enterica subspecies enterica serovar Typhimurium to induce enteric infection (Sal+) or saline control (Sal−). Cecal iron concentrations were 55-fold greater with Fe+Sal− compared to Fe−Sal−. Microbiome sequencing revealed shifts in gut microbiota with dietary iron and enteric infection. There was ∼30% more S. Typhimurium in the cecum of Fe+Sal+ compared to Fe−Sal+. Plasma hepcidin increased with dietary iron and enteric infection, but was greatest in Fe+Sal+. Plasma lipocalin-2 and spleen size relative to bodyweight were greater in Fe+Sal+ compared to Fe+Sal−, Fe−Sal− and Fe−Sal+, and Fe+Sal+ lost more bodyweight compared to Fe−Sal+. Unabsorbed iron in the lower intestine modifies the gut microbiome and promotes a more severe enteropathy. These findings could suggest the need for alternative iron supplementation strategies in areas where enteric infection are common.

A novel preparation for siderophore‐assisted copper and zinc enrichment in yeast

Copper and zinc are essential trace elements for several biological activities and play an important role in living organisms. In this study, the role of siderophores obtained from 16 microorganisms isolated from an iron-rich environment was evaluated in the transport of zinc and copper in yeast. In addition, siderophores showing relevant transport activity were used in the preparation of metal-enriched yeast. Siderophores TZT-SH5I and TZT-ZTH2X significantly improved tolerance of Saccharomyces cerevisiae during growth under high concentrations of zinc/copper. Strains producing siderophores TZT-SH5I and TZT-ZTH2X were identified as Aspergillus sp and Penicillium sp, respectively. The orthogonal method was used to determine optimized conditions for siderophore-assisted copper and zinc enrichment of S. cerevisiae. The final intracellular content of organic Cu and Zn in S. cerevisiae grown in a siderophore-containing medium was 60.76 and 44.22 mg/g. This study provides a convenient and feasible new strategy for the preparation of supplements rich in organic trace elements. Novelty impact statement Bioaccumulation of essential trace elements (TEs) by microorganisms is one of the most important ways to TEs from inorganic into organic forms which can be more efficiently absorbed by humans. In the current study, a novel method for preparing copper and zinc-enriched yeast using siderophores from high iron environment microorganisms has been optimized and established. Significantly higher intracellular content of organic Cu and Zn in Saccharomyces cerevisiae grown in a siderophore-containing medium was obtained, which would provide a new idea and platform for the preparation of organic trace elements.

Metagenome-Assembled Genomes from Monte Cristo Cave (Diamantina, Brazil) Reveal Prokaryotic Lineages As Functional Models for Life on Mars

Microbial communities have been explored in various terrestrial subsurface ecosystems, showing metabolic potentials that could generate noteworthy morphological and molecular biosignatures. Recent advancements in bioinformatic tools have allowed for descriptions of novel and yet-to-be cultivated microbial lineages in different ecosystems due to the genome reconstruction approach from metagenomic data. Using shotgun metagenomic data, we obtained metagenome-assembled genomes related to cultivated and yet-to-be cultivated prokaryotic lineages from a silica and iron-rich cave (Monte Cristo) in Minas Gerais State, Brazil. The Monte Cristo Cave has been shown to possess a high diversity of genes involved with different biogeochemical cycles, including reductive and oxidative pathways related to carbon, sulfur, nitrogen, and iron. Three genomes were selected for pangenomic analysis, assigned as Truepera sp., Ca. Methylomirabilis sp., and Ca. Koribacter sp. based on their lifestyles (radiation resistance, anaerobic methane oxidation, and potential iron oxidation). These bacteria exhibit genes involved with multiple DNA repair strategies, starvation, and stress response. Because these groups have few reference genomes deposited in databases, our study adds important genomic information about these lineages. The combination of techniques applied in this study allowed us to unveil the potential relationships between microbial genomes and their ecological processes with the cave mineralogy and highlight the lineages involved with anaerobic methane oxidation, iron oxidation, and radiation resistance as functional models for the search for extant life-forms outside our planet in silica- and iron-rich environments and potentially on Mars.

MP29-10 INCREASED PREVALENCE OF URINARY TRACT INFECTIONS AND CATHETER-ASSOCIATED URINARY TRACT INFECTIONS IN DISORDERS CHARACTERIZED BY IRON DYSREGULATION

You have accessJournal of UrologyInfections/Inflammation/Cystic Disease of the Genitourinary Tract: Kidney & Bladder II (MP29)1 Sep 2021MP29-10 INCREASED PREVALENCE OF URINARY TRACT INFECTIONS AND CATHETER-ASSOCIATED URINARY TRACT INFECTIONS IN DISORDERS CHARACTERIZED BY IRON DYSREGULATION Barbara Prol, Arrie Selva, Pamela Patton, Zhaoyi Chen, and Victoria Bird Barbara ProlBarbara Prol More articles by this author , Arrie SelvaArrie Selva More articles by this author , Pamela PattonPamela Patton More articles by this author , Zhaoyi ChenZhaoyi Chen More articles by this author , and Victoria BirdVictoria Bird More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002026.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Urinary tract infection (UTI) accounts for up to 40% of all healthcare-associated infections and its prevalence varies among different populations. Bacteria require iron-rich environments for optimal survival. Escherichia coli (E. coli), the most common pathogen responsible for UTI, has been shown to thrive in iron-rich environments. Our aim was to explore the prevalence of UTI and catheter-associated urinary tract infection (CAUTI) in a cohort of patients with iron-sequestering disorders compared to other populations. METHODS: The University of Florida Health Informatics for Integrating Biology and the Bedside (i2b2) system was queried for the purpose of retrospective analysis of UTI and CAUTI associated with E. coli sepsis. International Classification Codes (ICD-9 and ICD-10) were used to obtain our target diagnoses of interest, subjects with the classically iron-wasting diseases: sickle cell anemia (SS), thalassemia (T), and hemochromatosis (H). Control groups included the general population (GP) and subjects with Crohn’s disease (CD) and ulcerative colitis (UC). Univariate analysis was performed. We used SASv.9.4 for our analysis. P-values were calculated in comparison with the GP. RESULTS: A total of 1.1 million patients from 2012-2018 were included in our data query. UTI prevalence in GP, CD and UC was 4.8%, 12.8% and 12.5%, respectively (p <0.0001 for CD and UC). CAUTI prevalence in GP, CD, and UC was 0.1%, 0.4%, and 0.6%, respectively (p <0.0001 for CD and UC). In comparison, UTI prevalence in SS, T, and H was 21.1%, 14.8% and 14.9%, respectively (p <0.0001 for SS, T, and H). CAUTI prevalence in SS and H was 0.9 and 0.7%, respectively (p <0.0001 for SS and H). The prevalence of E. coli sepsis in SS, H, T, UC, and CD was 1.3%, 0.4%, 0.3%, 0.4%, 0.3%, respectively, and 0.05% in GP (p <0.0004 for T; p <0.0001 for SS, H, UC, and CD). CONCLUSIONS: Both iron-sequestering and iron-deficient disorders have a significantly higher prevalence of UTI and CAUTI when compared to the GP. In particular, our data suggest that individuals with SS represent a vulnerable group susceptible to all: UTI, CAUTI, urosepsis, and E. coli-related septicemia. Iron imbalance is a novel risk factor for the development of UTI and related infections. Efforts aimed at prevention of UTI should be pursued in these high-risk groups and further research should be directed towards this phenomenon. Source of Funding: none © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e493-e493 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Barbara Prol More articles by this author Arrie Selva More articles by this author Pamela Patton More articles by this author Zhaoyi Chen More articles by this author Victoria Bird More articles by this author Expand All Advertisement Loading ...

Mechanisms of arsenate and cadmium co-immobilized on ferrihydrite inferred from ternary surface configuration

Elucidating the interfacial interactions of arsenate (AsO43-) and cadmium (Cd) on minerals can better reveal their environmental behavior under various geological settings. Herein, the adsorption of Cd on ferrihydrite (Fh) in the presence of arsenate was investigated through batch experiments, surface complexation, and spectroscopic techniques. We determined the concentration-dependent interactions of Cd (II) and As (V) on each other’s behavior on Fh. Cadmium and arsenate tended to co-precipitate at high Cd/As ratios, whereas adsorption dominated at low Cd/As ratios. Compared with the single-ion system, the coexistence of Cd(II) and As on Fh significantly reduces the respective mobility of Cd(II) and As(V). The results of in situ attenuated total reflection–Fourier-transform infrared spectroscopy and charge distribution multisite complexation modeling revealed that the synergistic effects originated from electrostatic interactions and the formation of a ternary complex. The curve fitting of the spectra revealed three deconvolution peaks at ~ 765 cm−1, ~813 cm−1, and ~ 870 cm−1, which were assigned to As–OX (X = H+, cations, and H2O), As–O–Fe, and As–Oumcomplexed, respectively. After the addition of Cd(II), the intensity of As–OX increased at different pH values, indicating the formation of an As–O–Cd ternary complexes. We infer that two types of surface complex were assembled on the surface of Fh: namely anion-bridged Fe–As–Cd and cation-bridged Fe–Cd–As. These results contribute to our understanding of the behavior of multiple contaminates in an iron-rich environment and are helpful for the development of the corresponding restoration technology.

Quantifying Preservation Potential: Lipid Degradation in a Mars-Analog Circumneutral Iron Deposit.

Comparisons between the preservation potential of Mars-analog environments have historically been qualitative rather than quantitative. Recently, however, laboratory-based artificial maturation combined with kinetic modeling techniques have emerged as a potential means by which the preservation potential of solvent-soluble organic matter can be quantified in various Mars-analog environments. These methods consider how elevated temperatures, pressures, and organic-inorganic interactions influence the degradation of organic biomarkers post-burial. We used these techniques to investigate the preservation potential of deposits from a circumneutral iron-rich groundwater system. These deposits are composed of ferrihydrite (Fe5HO8 · 4H2O), an amorphous iron hydroxide mineral that is a common constituent of rocks found in ancient lacustrine environments on Mars, such as those observed in Gale Crater. Both natural and synthetic ferrihydrite samples were subjected to hydrous pyrolysis to observe the effects of long-term burial on the mineralogy and organic content of the samples. Our experiments revealed that organic-inorganic interactions in the samples are dominated by the transformation of iron minerals. As amorphous ferrihydrite transforms into more crystalline species, the decrease in surface area results in the desorption of organic matter, potentially rendering them more susceptible to degradation. We also find that circumneutral iron-rich deposits provide unfavorable conditions for the preservation of solvent-soluble organic matter. Quantitative comparisons between preservation potentials as calculated when using kinetic parameters show that circumneutral iron-rich deposits are ∼25 times less likely to preserve solvent-soluble organic matter compared with acidic, iron-rich environments. Our results suggest that circumneutral iron-rich deposits should be deprioritized in favor of acidic iron- and sulfur-rich deposits when searching for evidence of life with solvent extraction techniques.

An indigenous iron-reducing microbial community from MX80 bentonite - A study in the framework of nuclear waste disposal

Highly compacted MX80 bentonite has been selected as the engineered buffer and backfill material in several proposed concepts for long-term deep geological storage of nuclear waste. Iron-reducing bacteria reduce Fe (III) to Fe (II) and some are adapted to high temperatures and desiccated environments, in keeping with periods of less habitable conditions within the repository. In one potential UK repository concept, iron from carbon steel canisters may contribute to an iron-rich environment at the clay-canister interface. This could lead to changes in the mineralogy and iron-content of MX80 bentonite due to variation of the redox state and solubility, which in turn could alter the geomechanical properties of the clay. To investigate the potential role of iron-reducing bacteria in this process enrichments were carried out with both commercially available MX80 bentonite powder and compacted MX80 bentonite to identify the presence of an indigenous iron-interacting community in the clay. Throughout these enrichments Fe (II) soluble, Fe (II) total, and pH were measured, and the enrichments were subjected to 16S rRNA community analysis. Concentrations of Fe (II) total peaked at day 28 in all enrichments; however, the concentration was overall higher when accompanied by bacterial growth. Fe (II) soluble remained low throughout. 16S rRNA gene sequencing revealed the presence of several putative iron-interacting bacteria, as well as thermotolerant and spore-forming species. The indigenous community was largely comprised of firmicutes, including iron-reducers and spore-forming bacteria such as Desulfosporosinus. Therefore, MX80 bentonite inherently carries a viable microbial community which could potentially interact with structural iron present within MX80 bentonite or other mineral components, such as a carbon steel waste canister. Various research has shown that microbial activity is unlikely within the bulk bentonite provided high compaction is maintained. The importance of this high compaction is highlighted by the finding here of a viable, robust and functionally diverse community within the clay and activity may be possible anyway at edge sites and interfaces where, locally, swelling pressures might not fully develop.

Interferon-gamma promotes iron export in human macrophages to limit intracellular bacterial replication.

Salmonellosis and listeriosis together accounted for more than one third of foodborne illnesses in the United States and almost half the hospitalizations for gastrointestinal diseases in 2018 while tuberculosis afflicted over 10 million people worldwide causing almost 2 million deaths. Regardless of the intrinsic virulence differences among Listeria monocytogenes, Salmonella enterica and Mycobacterium tuberculosis, these intracellular pathogens share the ability to survive and persist inside the macrophage and other cells and thrive in iron rich environments. Interferon-gamma (IFN-γ) is a central cytokine in host defense against intracellular pathogens and has been shown to promote iron export in macrophages. We hypothesize that IFN-γ decreases iron availability to intracellular pathogens consequently limiting replication in these cells. In this study, we show that IFN-γ regulates the expression of iron-related proteins hepcidin, ferroportin, and ferritin to induce iron export from macrophages. Listeria monocytogenes, S. enterica, and M. tuberculosis infections significantly induce iron sequestration in human macrophages. In contrast, IFN-γ significantly reduces hepcidin secretion in S. enterica and M. tuberculosis infected macrophages. Similarly, IFN-γ-activated macrophages express higher ferroportin levels than untreated controls even after infection with L. monocytogenes bacilli; bacterial infection greatly down-regulates ferroportin expression. Collectively, IFN-γ significantly inhibits pathogen-associated intracellular iron sequestration in macrophages and consequently retards the growth of intracellular bacterial pathogens by decreasing iron availability.