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Zhou J, Wang X, Sun Z, Gu C, Gao J. The mechanisms of ·OH formation in MnO 2 and oxalate system: Implication for ATZ removal. J Hazard Mater 2024; 470:134213. [PMID: 38613958 DOI: 10.1016/j.jhazmat.2024.134213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 03/20/2024] [Accepted: 04/02/2024] [Indexed: 04/15/2024]
Abstract
Manganese oxides (MnO2) are commonly prevalent in groundwater, sediment and soil. In this study, we found that oxalate (H2C2O4) dissolved MnO2, leading to the formation of Mn(II)/(III), CO2(aq) and reactive oxygen species (·CO2-/O2·-/H2O2/·OH). Notably, CO2(aq) played a crucial role in ·OH formation, contributing to the degradation of atrazine (ATZ). To elucidate underneath mechanisms, a series of reactions with different gas-liquid ratios (GLR) were conducted. At the GLR of 0.3, 3.76, and + ∞ 79.4 %, 5.32 %, and 5.28 % of ATZ were eliminated, in which the cumulative ·OH concentration was 39.6 μM, 8.11 μM, and 7.39 μM and the cumulative CO2(aq) concentration was 11.2 mM, 4.7 mM, and 2.8 mM, respectively. The proposed reaction pathway was that CO2(aq) participated in the formation of a ternary complex [C2O4-Mn(II)-HCO4·3 H2O]-, which converted to a transition state (TS) as [C2O4-Mn(II)-CO3-OH·3 H2O]-, then decomposed to a complex radical [C2O4-Mn(II)-CO3·3 H2O]·- and ·OH after electron transfer within TS. It was novel to discover the role of CO2(aq) for ·OH yielding during MnO2 dissolution by H2C2O4. This finding helps revealing the overlooked processes that CO2(aq) influenced the fate of ATZ or other organic compounds in environment and providing us ideas for new technique development in contaminant remediation. ENVIRONMENTAL IMPLICATION: Manganese oxides and oxalate are common in soil, sediment and water. Their interactions could induce the formation of Mn(II)/(III), CO2(aq) and ·CO2-/O2·-/H2O2. This study found that atrazine could be effectively removed due to ·OH radicals under condition of high CO2(aq) concentration. The concentrations of Mn (0.0002-8.34 mg·L-1) and CO2(aq) (15-40 mg·L-1) were high in groundwater, and the surface water or rainfall seeps into groundwater and bring organic acids, which might promote the ·OH formation. The results might explain the missing steps of herbicides transformation in these environments and be helpful in developing new techniques in remediation in future.
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Affiliation(s)
- Jinjin Zhou
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Nanjing, No.188, Tianquan Road, Nanjing, Jiangsu Province 211135, China
| | - Xinghao Wang
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Zhaoyue Sun
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Cheng Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Juan Gao
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Nanjing, No.188, Tianquan Road, Nanjing, Jiangsu Province 211135, China.
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French KS, Chukwuma E, Linshitz I, Namba K, Duckworth OW, Cubeta MA, Baars O. Inactivation of siderophore iron-chelating moieties by the fungal wheat root symbiont Pyrenophora biseptata. Environ Microbiol Rep 2024; 16:e13234. [PMID: 38240404 PMCID: PMC10866069 DOI: 10.1111/1758-2229.13234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 12/28/2023] [Indexed: 02/15/2024]
Abstract
We investigated the ability of four plant and soil-associated fungi to modify or degrade siderophore structures leading to reduced siderophore iron-affinity in iron-limited and iron-replete cultures. Pyrenophora biseptata, a melanized fungus from wheat roots, was effective in inactivating siderophore iron-chelating moieties. In the supernatant solution, the tris-hydroxamate siderophore desferrioxamine B (DFOB) underwent a stepwise reduction of the three hydroxamate groups in DFOB to amides leading to a progressive loss in iron affinity. A mechanism is suggested based on the formation of transient ferrous iron followed by reduction of the siderophore hydroxamate groups during fungal high-affinity reductive iron uptake. P. biseptata also produced its own tris-hydroxamate siderophores (neocoprogen I and II, coprogen and dimerum acid) in iron-limited media and we observed loss of hydroxamate chelating groups during incubation in a manner analogous to DFOB. A redox-based reaction was also involved with the tris-catecholate siderophore protochelin in which oxidation of the catechol groups to quinones was observed. The new siderophore inactivating activity of the wheat symbiont P. biseptata is potentially widespread among fungi with implications for the availability of iron to plants and the surrounding microbiome in siderophore-rich environments.
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Affiliation(s)
- Katie S. French
- Department of Entomology and Plant PathologyNorth Carolina State University, Center for Integrated Fungal ResearchRaleighNorth CarolinaUSA
- Present address:
Department of Soil ScienceUniversity of ArkansasFayettevilleArkansasUSA
| | - Emmanuel Chukwuma
- Department of ChemistryNorth Carolina State UniversityRaleighNorth CarolinaUSA
| | - Ilan Linshitz
- Department of BiologyUniversity of MarylandCollege ParkMarylandUSA
| | - Kosuke Namba
- Department of Pharmaceutical SciencesTokushima UniversityTokushimaJapan
| | - Owen W. Duckworth
- Department of Crop and Soil SciencesNorth Carolina State UniversityRaleighNorth CarolinaUSA
| | - Marc A. Cubeta
- Department of Entomology and Plant PathologyNorth Carolina State University, Center for Integrated Fungal ResearchRaleighNorth CarolinaUSA
| | - Oliver Baars
- Department of Entomology and Plant PathologyNorth Carolina State University, Center for Integrated Fungal ResearchRaleighNorth CarolinaUSA
- Department of ChemistryNorth Carolina State UniversityRaleighNorth CarolinaUSA
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Ahmed MMA, Tripathi SK, Boudreau PD. Comparative metabolomic profiling of Cupriavidus necator B-4383 revealed production of cupriachelin siderophores, one with activity against Cryptococcus neoformans. Front Chem 2023; 11:1256962. [PMID: 37693169 PMCID: PMC10484230 DOI: 10.3389/fchem.2023.1256962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 08/07/2023] [Indexed: 09/12/2023] Open
Abstract
Cupriavidus necator H16 is known to be a rich source of linear lipopeptide siderophores when grown under iron-depleted conditions; prior literature termed these compounds cupriachelins. These small molecules bear β-hydroxyaspartate moieties that contribute to a photoreduction of iron when bound as ferric cupriachelin. Here, we present structural assignment of cupriachelins from C. necator B-4383 grown under iron limitation. The characterization of B-4383 cupriachelins is based on MS/MS fragmentation analysis, which was confirmed by 1D- and 2D-NMR for the most abundant analog (1). The cupriachelin congeners distinguish these two strains with differences in the preferred lipid tail; however, our rigorous metabolomic investigation also revealed minor analogs with changes in the peptide core, hinting at a potential mechanism by which these siderophores may reduce biologically unavailable ferric iron (4-6). Antifungal screening of the C. necator B-4383 supernatant extract and the isolated cupriachelin analog (1) revealed inhibitory activity against Cryptococcus neoformans, with IC50 values of 16.6 and 3.2 μg/mL, respectively. This antifungal activity could be explained by the critical role of the iron acquisition pathway in the growth and pathogenesis of the C. neoformans fungal pathogen.
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Affiliation(s)
- Mohammed M. A. Ahmed
- Boudreau Lab, Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS, United States
- Department of Pharmacognosy, Al-Azhar University, Cairo, Egypt
| | - Siddarth K. Tripathi
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, Oxford, MS, United States
| | - Paul D. Boudreau
- Boudreau Lab, Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS, United States
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4
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Roskova Z, Skarohlid R, McGachy L. Siderophores: an alternative bioremediation strategy? Sci Total Environ 2022; 819:153144. [PMID: 35038542 DOI: 10.1016/j.scitotenv.2022.153144] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 05/15/2023]
Abstract
Siderophores are small molecular weight iron scavengers that are mainly produced by bacteria, fungi, and plants. Recently, they have attracted increasing attention because of their potential role in environmental bioremediation. Although siderophores are generally considered to exhibit high specificity for iron, they have also been reported to bind to various metal and metalloid ions. This unique ability allows siderophores to solubilise and mobilise heavy metals and metalloids from soil, thereby facilitating their bioremediation. In addition, because of their redox nature, they can mediate the production of reactive oxygen species (ROS), and thus promote the biodegradation of organic contaminants. The aim of this review is to summarise the existing knowledge on the developed strategies of siderophore-assisted bioremediation of metals, metalloids, and organic contaminants. Additionally, this review also includes the biosynthesis and classification of microbial and plant siderophores.
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Affiliation(s)
- Zuzana Roskova
- Department of Environmental Chemistry, University of Chemistry and Technology Prague, Technická 5, 16628 Prague, Czech Republic
| | - Radek Skarohlid
- Department of Environmental Chemistry, University of Chemistry and Technology Prague, Technická 5, 16628 Prague, Czech Republic
| | - Lenka McGachy
- Department of Environmental Chemistry, University of Chemistry and Technology Prague, Technická 5, 16628 Prague, Czech Republic.
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5
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Emmeline D, Alexandra L, Hervé C, Pierre G, Jean-Yves C, Thierry L. Effect of Pseudomonas putida-producing pyoverdine on copper uptake by Helianthus annuus cultivated on vineyard soils. Sci Total Environ 2022; 809:152113. [PMID: 34875330 DOI: 10.1016/j.scitotenv.2021.152113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 11/27/2021] [Accepted: 11/27/2021] [Indexed: 06/13/2023]
Abstract
Bioaugmentation-assisted phytoextraction was used to reduce the Cu load in vineyard soils. While performance is usually the endpoint of such studies, here we identified some mechanisms underlying Cu soil to plant transfer, particularly the role of siderophores in the extraction of Cu from the soil-bearing phases and its phytoavailability. Carbonated vs. non‑carbonated vineyard soils were cultivated with sunflower in rhizoboxes bioaugmented with Pseudomonas putida. gfp-Tagged P. putida was monitored in the soil and pyoverdine (Pvd), Cu, Fe, Mn, and Zn were measured in the soil solution. Trace elements (TE) were analysed in the roots and shoots. Plant growth and nutritional status were also measured. With bioaugmentation, the concentration of total Cu (vs. Cu2+) in the soil solution increased (decreased) by a factor of 1.6 to 2.6 (7 to 13) depending on the soil. The almost 1:1 relationship between the excess of Fe + Cu mobilized from the solid phase and the amount of Pvd in the soil solution in bioaugmented treatments suggests that Pvd mobilized Fe and Cu mainly by ligand-controlled dissolution via a 1:1 metal-Pvd complex. Bioaugmentation increased the Cu concentration by 17% in the shoots and by 93% in the roots, and by 30% to 60% the sunflower shoot biomass leading to an increase in the amount of Cu phytoextracted by up to 87%. The amount of Fe, Mn, Zn, and P also increased in the roots and shoots. Contrary to what was expected, carbonated soil did not increase the mobilization of TE. Our results showed that bioaugmentation increased phytoextraction, and its performance can be further improved by promoting the dissociation of Pvd-Cu complex in the solution at the soil-root interface.
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Affiliation(s)
- D'Incau Emmeline
- LPG, UMR 6112 CNRS-Université de Nantes, BP 92208, 44322 Nantes cedex 3, France
| | - Lépinay Alexandra
- OSUNA, UMS 3281 CNRS-Université de Nantes, BP 92208, 44322 Nantes cedex 3, France
| | - Capiaux Hervé
- LPG, UMR 6112 CNRS-Université de Nantes, BP 92208, 44322 Nantes cedex 3, France; OSUNA, UMS 3281 CNRS-Université de Nantes, BP 92208, 44322 Nantes cedex 3, France
| | - Gaudin Pierre
- LPG, UMR 6112 CNRS-Université de Nantes, BP 92208, 44322 Nantes cedex 3, France; OSUNA, UMS 3281 CNRS-Université de Nantes, BP 92208, 44322 Nantes cedex 3, France
| | - Cornu Jean-Yves
- ISPA, Bordeaux Sciences Agro, INRA, 33140 Villenave d'Ornon, France
| | - Lebeau Thierry
- LPG, UMR 6112 CNRS-Université de Nantes, BP 92208, 44322 Nantes cedex 3, France; OSUNA, UMS 3281 CNRS-Université de Nantes, BP 92208, 44322 Nantes cedex 3, France.
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Doydora SA, Baars O, Harrington JM, Duckworth OW. Salicylate coordination in metal-protochelin complexes. Biometals 2021; 35:87-98. [PMID: 34837588 DOI: 10.1007/s10534-021-00352-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/17/2021] [Indexed: 11/29/2022]
Abstract
Molybdenum (Mo) is an essential trace element for bacteria that is utilized in myriad metalloenzymes that directly couple to the biogeochemical cycling of nitrogen, sulfur, and carbon. In particular, Mo is found in the most common nitrogenase enzyme, and the scarcity and low bioavailability of Mo in soil may be a critical factor that contributes to the limitation of nitrogen fixation in forests and agroenvironments. To overcome this scarcity, microbes produce exudates that specifically chelate scarce metals, promoting their solubilization and uptake. Here, we have determined the structure and stability constants of Mo bound by protochelin, a siderophore produced by bacteria under Mo-depleted conditions. Spectrophotometric titration spectra indicated a coordination shift from a catecholate to salicylate binding mode for MoVI-protochelin (Mo-Proto) complexes at pH < 5. pKa values obtained from analysis of titrations were 4.8 ± 0.3 for MoVIO2H3Proto- and 3.3 ± 0.1 for MoVIO2H4Proto. The occurrence of negatively charged Mo-Proto complexes at pH 6 was also confirmed by mass spectrometry. K-edge Extended X-ray absorption fine structure spectroscopy confirmed the change in Mo coordination at low pH, and structural fitting provides insights into the physical architecture of complexes at neutral and acidic pH. These findings suggest that Mo can be chelated by protochelin across a wide environmental pH range, with a coordination shift occurring at pH < 5. This chelation and associated coordination shift may impact biological availability and mineral surface retention of Mo under acidic conditions.
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Affiliation(s)
- Sarah A Doydora
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, 27695, USA
| | - Oliver Baars
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, 27695, USA
| | - James M Harrington
- RTI International, 3040 East Cornwallis Road, Research Triangle Park, NC, 27709-2194, USA
| | - Owen W Duckworth
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, 27695, USA.
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Li H, Santos F, Butler K, Herndon E. A Critical Review on the Multiple Roles of Manganese in Stabilizing and Destabilizing Soil Organic Matter. Environ Sci Technol 2021; 55:12136-12152. [PMID: 34469151 DOI: 10.1021/acs.est.1c00299] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Manganese (Mn) is a biologically important and redox-active metal that may exert a poorly recognized control on carbon (C) cycling in terrestrial ecosystems. Manganese influences ecosystem C dynamics by mediating biochemical pathways that include photosynthesis, serving as a reactive intermediate in the breakdown of organic molecules, and binding and/or oxidizing organic molecules through organo-mineral associations. However, the potential for Mn to influence ecosystem C storage remains unresolved. Although substantial research has demonstrated the ability of Fe- and Al-oxides to stabilize organic matter, there is a scarcity of similar information regarding Mn-oxides. Furthermore, Mn-mediated reactions regulate important litter decomposition pathways, but these processes are poorly constrained across diverse ecosystems. Here, we discuss the ecological roles of Mn in terrestrial environments and synthesize existing knowledge on the multiple pathways by which biogeochemical Mn and C cycling intersect. We demonstrate that Mn has a high potential to degrade organic molecules through abiotic and microbially mediated oxidation and to stabilize organic molecules, at least temporarily, through organo-mineral associations. We outline research priorities needed to advance understanding of Mn-C interactions, highlighting knowledge gaps that may address key uncertainties in soil C predictions.
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Affiliation(s)
- Hui Li
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Fernanda Santos
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Kristen Butler
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Earth and Planetary Sciences, College of Arts & Sciences, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Elizabeth Herndon
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Earth and Planetary Sciences, College of Arts & Sciences, University of Tennessee, Knoxville, Tennessee 37996, United States
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Whitaker AH, Austin RE, Holden KL, Jones JL, Michel FM, Peak D, Thompson A, Duckworth OW. The Structure of Natural Biogenic Iron (Oxyhydr)oxides Formed in Circumneutral pH Environments. Geochim Cosmochim Acta 2021; 308:237-255. [PMID: 34305159 PMCID: PMC8294128 DOI: 10.1016/j.gca.2021.05.059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Biogenic iron (Fe) (oxyhydr)oxides (BIOS) partially control the cycling of organic matter, nutrients, and pollutants in soils and water via sorption and redox reactions. Although recent studies have shown that the structure of BIOS resembles that of two-line ferrihydrite (2LFh), we lack detailed knowledge of the BIOS local coordination environment and structure required to understand the drivers of BIOS reactivity in redox active environments. Therefore, we used a combination of microscopy, scattering, and spectroscopic methods to elucidate the structure of BIOS sampled from a groundwater seep in North Carolina and compare them to 2LFh. We also simulated the effects of wet-dry cycles by varying sample preparation (e.g., freezing, flash freezing with freeze drying, freezing with freeze drying and oven drying). In general, the results show that both the long- and short-range ordering in BIOS are structurally distinct and notably more disordered than 2LFh. Our structure analysis, which utilized Fe K-edge X-ray absorption spectroscopy, Mössbauer spectroscopy, X-ray diffraction, and pair distribution function analyses, showed that the BIOS samples were more poorly ordered than 2LFh and intimately mixed with organic matter. Furthermore, pair distribution function analyses resulted in coherent scattering domains for the BIOS samples ranging from 12-18 Å, smaller than those of 2LFh (21-27 Å), consistent with reduced ordering. Additionally, Fe L-edge XAS indicated that the local coordination environment of 2LFh samples consisted of minor amounts of tetrahedral Fe(III), whereas BIOS were dominated by octahedral Fe(III), consistent with depletion of the sites due to small domain size and incorporation of impurities (e.g., organic C, Al, Si, P). Within sample sets, the frozen freeze dried and oven dried sample preparation increased the crystallinity of the 2LFh samples when compared to the frozen treatment, whereas the BIOS samples remained more poorly crystalline under all sample preparations. This research shows that BIOS formed in circumneutral pH waters are poorly ordered and more environmentally stable than 2LFh.
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Affiliation(s)
- Andrew H. Whitaker
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Robert E. Austin
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Kathryn L. Holden
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Jacob L. Jones
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - F. Marc Michel
- Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24060, USA
| | - Derek Peak
- Department of Soil Science, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5A8, Canada
| | - Aaron Thompson
- Department of Crop and Soil Sciences, University of Georgia, Athens, Georgia 30602, USA
| | - Owen W. Duckworth
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
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Rai V, Fisher N, Duckworth OW, Baars O. Extraction and Detection of Structurally Diverse Siderophores in Soil. Front Microbiol 2020; 11:581508. [PMID: 33042099 PMCID: PMC7527475 DOI: 10.3389/fmicb.2020.581508] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 08/17/2020] [Indexed: 12/16/2022] Open
Abstract
Although the biochemistry of bacterial and fungal siderophores has been intensively studied in laboratory cultures, their distribution and impacts on nutrient cycling and microbial communities in soils remain poorly understood. The detection of siderophores in soil is an analytical challenge because of the complexity of the soil matrix and their structural diversity. Liquid chromatography-mass spectrometry (LC-MS) is a suitable method for the sensitive analysis of siderophores in complex samples; however, siderophore extraction into liquid phases for analysis by LC-MS is problematic because of their adsorption to soil particles and organic matter. To determine extraction efficiencies of structurally diverse siderophores, spike-recovery experiments were set up with standards representing the three main siderophore classes: the hydroxamate desferrioxamine B (DFOB), the α-hydroxycarboxylate rhizoferrin, and the catecholate protochelin. Previously used solvent extractions with water or methanol recovered only a small fraction (< 35%) of siderophores, including < 5% for rhizoferrin and protochelin. We designed combinatorial chemical extractions (22 total solutions) to target siderophores associated with different soil components. A combination of calcium chloride and ascorbate achieved high and, for some soils, quantitative extraction of DFOB and rhizoferrin. Protochelin analysis was complicated by potential fast oxidation and interactions with colloidal soil components. Using the optimized extraction method, we detected α-hydroxycarboxylate type siderophores (viz. rhizoferrin, vibrioferrin, and aerobactin) in soil for the first time. Concentrations reached 461 pmol g-1, exceeding previously reported concentrations of siderophores in soil and suggesting a yet unrecognized importance of α-hydroxycarboxylate siderophores for biological interactions and biogeochemical processes in soil.
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Affiliation(s)
- Vineeta Rai
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - Nathaniel Fisher
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States
| | - Owen W. Duckworth
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, United States
| | - Oliver Baars
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
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Li W, Liu XM. Mobilization and partitioning of rare earth elements in the presence of humic acids and siderophores. Chemosphere 2020; 254:126801. [PMID: 32334256 DOI: 10.1016/j.chemosphere.2020.126801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 04/11/2020] [Accepted: 04/12/2020] [Indexed: 06/11/2023]
Abstract
Developing rare earth elements (plus yttrium, REY) as a group of environmental tracer requires comprehensive understandings in their geochemical behaviors associated with natural organic matter. Recent work highlighted the promotions on REY mobilization and cerium oxidation by siderophores during silicate dissolution, but the mechanism remained ambiguous. Here, we performed batch fluid-rock interaction experiments to explore the functions of siderophore desferrioxamine B (DFOB) and humic acids (HA) towards REY mobility and partitioning during REY-bearing ferrihydrite dissolution. To acquire in-depth knowledge of organic controls on REY, we used multiple strategies, including elemental, multispectral, and electrochemical analyses, to investigate the organic regulation on REY geochemistry. This study sheds light on the function of ligand-specific selectivity and solid-fluid organic molecular fractionation, primarily dependent on hydrochemical settings (pH, organic compounds, ionic strength, and oxicity). Our results confirm the catalytic oxidation ability of ligand, which forms DFOB-Ce(IV) (K = 1042, electrochemistry), producing positive Ce anomalies in solutions by ligand-driven redox shifting. Both HA and DFOB showed high affinities to HREY, and facilitated LREY/HREY partitioning. The mobilization of REY and the development of Ce anomalies were limited by HA coatings that modified surface properties and disturbed the approach of DFOB. Excess siderophores attack inert HA coatings, facilitating REY liberation and Ce redox activities. The release of REY and catalytic oxidation of Ce can be inhibited at high ionic strength or under oxygen deficiency. Our study reveals that natural organic matter significantly influences the fate of REY in iron oxides, and crucial for the biogeochemical cycles of REY in nature.
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Affiliation(s)
- Wenshuai Li
- Department of Geological Sciences, University of North Carolina-Chapel Hill, NC, USA.
| | - Xiao-Ming Liu
- Department of Geological Sciences, University of North Carolina-Chapel Hill, NC, USA.
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11
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Zhang X, Baars O, Morel FMM. Genetic, structural, and functional diversity of low and high-affinity siderophores in strains of nitrogen fixing Azotobacter chroococcum. Metallomics 2020; 11:201-212. [PMID: 30444515 DOI: 10.1039/c8mt00236c] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
To increase iron (Fe) bioavailability in surface soils, microbes secrete siderophores, chelators with widely varying Fe affinities. Strains of the soil bacterium Azotobacter chroococcum (AC), plant-growth promoting rhizobacteria used as agricultural inoculants, require high Fe concentrations for aerobic respiration and nitrogen fixation. Recently, A. chroococcum str. NCIMB 8003 was shown to synthesize three siderophore classes: (1) vibrioferrin, a low-affinity α-hydroxy carboxylate (pFe = 18.4), (2) amphibactins, high-affinity tris-hydroxamates, and (3) crochelin A, a high-affinity siderophore with mixed Fe-chelating groups (pFe = 23.9). The relevance and specific functions of these siderophores in AC strains remain unclear. We analyzed the genome and siderophores of a second AC strain, A. chroococcum str. B3, and found that it also produces vibrioferrin and amphibactins, but not crochelin A. Genome comparisons indicate that vibrioferrin production is a vertically inherited, conserved strategy for Fe uptake in A. chroococcum and other species of Azotobacter. Amphibactin and crochelin biosynthesis reflects a more complex evolutionary history, shaped by vertical gene transfer, gene gain and loss through recombination at a genomic hotspot. We found conserved patterns of low vs. high-affinity siderophore production across strains: the low-affinity vibrioferrin was produced by mildly Fe limited cultures. As cells became more severely Fe starved, vibrioferrin production decreased in favor of high-affinity amphibactins (str. B3, NCIMB 8003) and crochelin A (str. NCIMB 8003). Our results show the evolution of low and high-affinity siderophore families and conserved patterns for their production in response to Fe bioavailability in a common soil diazotroph.
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Affiliation(s)
- Xinning Zhang
- Department of Geosciences, Princeton University, USA.
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Sowers TD, Wani RP, Coward EK, Fischel MHH, Betts AR, Douglas TA, Duckworth OW, Sparks DL. Spatially Resolved Organomineral Interactions across a Permafrost Chronosequence. Environ Sci Technol 2020; 54:2951-2960. [PMID: 32023050 DOI: 10.1021/acs.est.9b06558] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Permafrost contains a large (1700 Pg C) terrestrial pool of organic matter (OM) that is susceptible to degradation as global temperatures increase. Of particular importance is syngenetic Yedoma permafrost containing high OM content. Reactive iron phases promote stabilizing interactions between OM and soil minerals and this stabilization may be of increasing importance in permafrost as the thawed surface region ("active layer") deepens. However, there is limited understanding of Fe and other soil mineral phase associations with OM carbon (C) moieties in permafrost soils. To elucidate the elemental associations involved in organomineral complexation within permafrost systems, soil cores spanning a Pleistocene permafrost chronosequence (19,000, 27,000, and 36,000 years old) were collected from an underground tunnel near Fairbanks, Alaska. Subsamples were analyzed via scanning transmission X-ray microscopy-near edge X-ray absorption fine structure spectroscopy at the nano- to microscale. Amino acid-rich moieties decreased in abundance across the chronosequence. Strong correlations between C and Fe with discrete Fe(III) or Fe(II) regions selectively associated with specific OM moieties were observed. Additionally, Ca coassociated with C through potential cation bridging mechanisms. Results indicate Fe(III), Fe(II), and mixed valence phases associated with OM throughout diverse permafrost environments, suggesting that organomineral complexation is crucial to predict C stability as permafrost systems warm.
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Affiliation(s)
- Tyler D Sowers
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
- Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, Durham, North Carolina 27711, United States
| | - Rucha P Wani
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
| | - Elizabeth K Coward
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
| | - Matthew H H Fischel
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
| | - Aaron R Betts
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
| | - Thomas A Douglas
- U.S. Army Cold Regions Research & Engineering Laboratory, 9th Avenue, Building 4070, Fort Wainwright, Fairbanks, 99703 Alaska, United States
| | - Owen W Duckworth
- Department of Crop and Soil Sciences, North Carolina State University, 101 Derieux Street, Campus Box 7620, Raleigh, North Carolina 26795, United States
| | - Donald L Sparks
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
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Hofmann M, Retamal-Morales G, Tischler D. Metal binding ability of microbial natural metal chelators and potential applications. Nat Prod Rep 2020; 37:1262-1283. [DOI: 10.1039/c9np00058e] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Metallophores can chelate many different metal and metalloid ions next to iron, make them valuable for many applications.
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Affiliation(s)
- Marika Hofmann
- Institute of Biosciences
- Chemistry and Physics Faculty
- TU Bergakademie Freiberg
- 09599 Freiberg
- Germany
| | - Gerardo Retamal-Morales
- Laboratorio de Microbiología Básica y Aplicada
- Facultad de Química y Biología
- Universidad de Santiago de Chile
- Santiago
- Chile
| | - Dirk Tischler
- Microbial Biotechnology
- Ruhr-Universität Bochum
- 44780 Bochum
- Germany
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Abstract
The mobility and toxicity of chromium (Cr) in soil and water systems are largely controlled by its oxidation state and interactions with solid phases. Relative to abiotic minerals, biogenic iron (Fe) (oxyhydr)oxides (BIOS) may enhance Cr(vi) adsorption and reduction due to their poorly ordered structures, large surface areas, and incorporation of cell derived organic matter. To determine the extent and mechanisms of the reaction between Cr(vi) and BIOS, sorption isotherm and kinetic studies were conducted using two-line ferrihydrite, BIOS, and BIOS amended with 0.135 M ferrozine (an Fe(ii) chelator). X-ray absorption near edge structure (XANES) spectroscopy of BIOS reacted with Cr(vi) showed approximately 50% reduction of the total sorbed Cr from Cr(vi) to Cr(iii) after 14 days of exposure. Sorbed Cr(iii) was best fit with an organic carboxylate complex after 1 d of reaction, but after 7 d mineral-associated Cr(iii) was the predominant form. In the presence of ferrozine, Cr(vi) reduction by BIOS was inhibited, confirming a key role for Fe(ii) as the Cr(vi) reductant. However, the lack of a 3 : 1 reaction stoichiometry between Fe(ii) and Cr(iii) produced suggests roles for reaction with organic matter and Cr(v) autoreduction in Cr(iii) production. This study thus elucidates an unrecognized mechanism of Cr sequestration by ubiquitous natural Fe (oxyhydr)oxide deposits. Furthermore, the redox transformation of mobile Cr(vi) to less soluble Cr(iii) species observed in our study implies that biogenic Fe (oxyhydr)oxides in soils and natural waters may naturally attenuate Cr(vi) concentrations through sorption and reduction processes, thus limiting its transport to downstream environments.
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Affiliation(s)
- Andrew H Whitaker
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695-7620, USA.
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Affiliation(s)
- James G. Roberts
- North Carolina State University, Department of Chemistry, Raleigh, NC 27695, United States
| | - Leslie A. Sombers
- North Carolina State University, Department of Chemistry, Raleigh, NC 27695, United States
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Saad EM, Wang X, Planavsky NJ, Reinhard CT, Tang Y. Redox-independent chromium isotope fractionation induced by ligand-promoted dissolution. Nat Commun 2017; 8:1590. [PMID: 29150598 PMCID: PMC5693864 DOI: 10.1038/s41467-017-01694-y] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 10/09/2017] [Indexed: 11/24/2022] Open
Abstract
The chromium (Cr) isotope system has emerged as a potential proxy for tracing the Earth’s atmospheric evolution based on a redox-dependent framework for Cr mobilization and isotope fractionation. Although studies have demonstrated that redox-independent pathways can also mobilize Cr, no quantitative constraints exist on the associated isotope fractionations. Here we survey the effects of common environmental ligands on the dissolution of Cr(III)-(oxy)hydroxide solids and associated Cr isotope fractionation. For a variety of organic acids and siderophores, δ53Cr values of dissolved Cr(III) are −0.27 to 1.23‰, within the range of previously observed Cr isotope signatures in rock records linked to Cr redox cycling. Thus, ligand-promoted dissolution of Cr-containing solids, a redox-independent process, must be taken into account when using sedimentary Cr isotope signatures to diagnose atmospheric oxygen levels. This work provides a step towards establishing a more robust framework for using Cr isotopes to track the evolution of the Earth’s atmosphere. The chromium (Cr) isotope system has emerged as a potential proxy for tracing Earth’s atmospheric evolution based on a redox-dependent framework. Here the authors show that ligand-complexation, a redox-independent process, must be considered when using Cr isotope signatures to diagnose atmospheric oxygen levels.
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Affiliation(s)
- Emily M Saad
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Xiangli Wang
- Department of Geology and Geophysics, Yale University, New Haven, CT, 06511, USA
| | - Noah J Planavsky
- Department of Geology and Geophysics, Yale University, New Haven, CT, 06511, USA
| | - Christopher T Reinhard
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Yuanzhi Tang
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
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Baars O, Zhang X, Morel FMM, Seyedsayamdost MR. The Siderophore Metabolome of Azotobacter vinelandii. Appl Environ Microbiol 2016; 82:27-39. [PMID: 26452553 PMCID: PMC4702634 DOI: 10.1128/aem.03160-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/02/2015] [Indexed: 12/14/2022] Open
Abstract
In this study, we performed a detailed characterization of the siderophore metabolome, or "chelome," of the agriculturally important and widely studied model organism Azotobacter vinelandii. Using a new high-resolution liquid chromatography-mass spectrometry (LC-MS) approach, we found over 35 metal-binding secondary metabolites, indicative of a vast chelome in A. vinelandii. These include vibrioferrin, a siderophore previously observed only in marine bacteria. Quantitative analyses of siderophore production during diazotrophic growth with different sources and availabilities of Fe showed that, under all tested conditions, vibrioferrin was present at the highest concentration of all siderophores and suggested new roles for vibrioferrin in the soil environment. Bioinformatic searches confirmed the capacity for vibrioferrin production in Azotobacter spp. and other bacteria spanning multiple phyla, habitats, and lifestyles. Moreover, our studies revealed a large number of previously unreported derivatives of all known A. vinelandii siderophores and rationalized their origins based on genomic analyses, with implications for siderophore diversity and evolution. Together, these insights provide clues as to why A. vinelandii harbors multiple siderophore biosynthesis gene clusters. Coupled with the growing evidence for alternative functions of siderophores, the vast chelome in A. vinelandii may be explained by multiple, disparate evolutionary pressures that act on siderophore production.
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Affiliation(s)
- Oliver Baars
- Department of Geosciences, Princeton University, Princeton, New Jersey, USA
| | - Xinning Zhang
- Department of Geosciences, Princeton University, Princeton, New Jersey, USA
| | - François M M Morel
- Department of Geosciences, Princeton University, Princeton, New Jersey, USA
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Abstract
Bacteria secrete small molecules known as siderophores to acquire iron from their surroundings. For over 60 years, investigations into the bioinorganic chemistry of these molecules, including fundamental coordination chemistry studies, have provided insight into the crucial role that siderophores play in bacterial iron homeostasis. The importance of understanding the fundamental chemistry underlying bacterial life has been highlighted evermore in recent years because of the emergence of antibiotic-resistant bacteria and the need to prevent the global rise of these superbugs. Increasing reports of siderophores functioning in capacities other than iron transport have appeared recently, but reports of "non-classical" siderophore functions have long paralleled those of iron transport. One particular non-classical function of these iron chelators, namely antibiotic activity, was documented before the role of siderophores in iron transport was established. In this Perspective, we present an exposition of past and current work into non-classical functions of siderophores and highlight the directions in which we anticipate that this research is headed. Examples include the ability of siderophores to function as zincophores, chalkophores, and metallophores for a variety of other metals, sequester heavy metal toxins, transport boron, act as signalling molecules, regulate oxidative stress, and provide antibacterial activity.
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Affiliation(s)
- Timothy C Johnstone
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Harrington JM, Duckworth OW, Haselwandter K. The fate of siderophores: antagonistic environmental interactions in exudate-mediated micronutrient uptake. Biometals 2015; 28:461-72. [DOI: 10.1007/s10534-015-9821-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/07/2015] [Indexed: 11/25/2022]
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Ferret C, Sterckeman T, Cornu JY, Gangloff S, Schalk IJ, Geoffroy VA. Siderophore-promoted dissolution of smectite by fluorescent Pseudomonas. Environ Microbiol Rep 2014; 6:459-67. [PMID: 25646536 DOI: 10.1111/1758-2229.12146] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Siderophores are organic chelators produced by microorganisms to fulfil their iron requirements. Siderophore-promoted dissolution of iron-bearing minerals has been clearly documented for some siderophores, but few studies have addressed metabolizing siderophore-producing bacteria. We investigated iron acquisition from clays by fluorescent Pseudomonads, bacteria that are ubiquitous in the environment. We focused on the interactions between smectite and Pseudomonas aeruginosa, a bacterium producing two structurally different siderophores: pyoverdine and pyochelin. The presence of smectite in iron-limited growth media promoted planktonic growth of P. aeruginosa and biofilm surrounding the smectite aggregates. Chemical analysis of the culture media indicated increases in the dissolved silicon, iron and aluminium concentrations following smectite supplementation. The use of P. aeruginosa mutants unable to produce either one or both of the two siderophores indicated that pyoverdine, the siderophore with the higher affinity for iron, was involved in iron and aluminium solubilization by the wild-type strain. However, in the absence of pyoverdine, pyochelin was also able to solubilize iron but with a twofold lower efficiency. In conclusion, pyoverdine and pyochelin, two structurally different siderophores, can solubilize structural iron from smectite and thereby make it available for bacterial growth.
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Boisa N, Elom N, Dean JR, Deary ME, Bird G, Entwistle JA. Development and application of an inhalation bioaccessibility method (IBM) for lead in the PM10 size fraction of soil. Environ Int 2014; 70:132-42. [PMID: 24934854 DOI: 10.1016/j.envint.2014.05.021] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 05/23/2014] [Accepted: 05/28/2014] [Indexed: 05/21/2023]
Abstract
An approach for assessing the inhalation bioaccessibility of Pb in the PM10 size fraction is presented, using an in vitro simulated epithelial lung fluid to represent the extracellular environment of the lung. The developed inhalation bioaccessibility method (IBM) is applied to a range of urban surface soils and mining wastes obtained from Mitrovica, Kosovo, a site where impacts upon human health following exposure to Pb have been internationally publicised. All Pb determinations were undertaken by inductively coupled plasma mass spectrometry (ICP-MS). The pseudo-total concentration of Pb (microwave acid digestion using aqua-regia) varied between matrices: smelter (20,900-72,800mgkg(-1)), topsoil (274-13,700mgkg(-1)), and tailings (2990mgkg(-1)-25,300mgkg(-1)). The in vitro inhalation bioaccessibility was typically several orders of magnitude lower: smelter (7.0-965mgkg(-1)), topsoil (9.8-1060mgkg(-1)), and tailings (0.7mgkg(-1)-49.2mgkg(-1)). The % inhalation bioaccessibility ranged from 0.02 to 11.0%, with the higher inhalation bioaccessible Pb concentrations being observed for samples from the Bosniak Mahalla area of Mitrovica (an area proposed for the relocation of internally displaced peoples). The estimated inhalation dose (for adults) calculated from the PM10 pseudo-total Pb concentration ranged from 0.369 to 1.284μgkg(-1)BWday(-1) (smelter), 0.005-0.242μgkg(-1)BWday(-1) (topsoil), and 0.053-0.446μgkg(-1)BWday(-1) (tailings). When daily inhalation doses were calculated using the bioaccessible Pb concentration the modelled exposure doses were much lower: smelter (0.0001-0.0170μgkg(-1)BWday(-1)), topsoil (0.0002-0.0187μgkg(-1)BWday(-1)) and tailings (0.0001-0.0009μgkg(-1)BWday(-1)). Modelled for the neutral pH conditions of the interstitial lung environment, the results indicate a low potential inhalation bioaccessibility for Pb in these samples. Given the already elevated environmental Pb burden experienced by the local population, where significant prolonged dust or particulate generating activities are taking place, or where the inhaled particles are phagocytized, then inhalation exposure has the potential to significantly add to the overall Pb burden. Such data are important for local policy makers to better enable them to assess risk, especially in areas where soils/dusts have elevated levels of contamination.
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Affiliation(s)
- Ndokiari Boisa
- Engineering and Environment, Northumbria University, Ellison Building, Newcastle Upon Tyne, NE1 8ST, UK
| | - Nwabueze Elom
- Department of Applied Sciences, Northumbria University, Ellison Building, Newcastle Upon Tyne, NE1 8ST, UK
| | - John R Dean
- Department of Applied Sciences, Northumbria University, Ellison Building, Newcastle Upon Tyne, NE1 8ST, UK
| | - Michael E Deary
- Engineering and Environment, Northumbria University, Ellison Building, Newcastle Upon Tyne, NE1 8ST, UK
| | - Graham Bird
- School of Environment, Natural Resources and Geography, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
| | - Jane A Entwistle
- Engineering and Environment, Northumbria University, Ellison Building, Newcastle Upon Tyne, NE1 8ST, UK.
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Duckworth OW, Akafia MM, Andrews MY, Bargar JR. Siderophore-promoted dissolution of chromium from hydroxide minerals. Environ Sci Process Impacts 2014; 16:1348-1359. [PMID: 24683601 DOI: 10.1039/c3em00717k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Biomolecules have significant impacts on the fate and transport of contaminant metals in soils and natural waters. Siderophores, Fe(iii)-binding agents that are exuded by microbes and plants, may form strong complexes with and promote the dissolution of contaminant metal ions, such as Co(iii), U(iv), or Pu(iv). Although aqueous Cr(iii)-siderophore complexes have been recognized in the laboratory setting for almost 40 years, few studies have explored interactions of siderophores with Cr-bearing minerals or considered their impacts on environmental chemistry. To better understand the possible effects of siderophores on chromium mobility, we conducted a series of dissolution experiments to quantify the dissolution rates of Cr(iii)(OH)3 in the presence of hydroxamate, catecholate, and α-hydroxycarboxylate siderophores over a range of environmentally relevant pH values. At pH = 5, dissolution rates in the presence of siderophores are similar to control experiments, suggesting a predominantly proton-promoted dissolution mechanism. At pH = 8, the sorption of the siderophores desferrioxamine B and rhizoferrin can be modeled by using Langmuir isotherms. The dissolution rates for these siderophores are proportional to the surface concentrations of sorbed siderophore, and extended X-ray absorption fine structure spectra of dissolution products indicates the formation of Cr(iii)HDFOB(+) and Cr(iii)rhizoferrin(3-) complexes, suggesting a ligand-promoted dissolution mechanism at alkaline pH. Because siderophores promote Cr(iii)(OH)3 dissolution at rates similar in magnitude to those of iron hydroxides and the resulting Cr(iii)-siderophore complexes may be persistent in solution, siderophores could potentially contribute to the mobilization of Cr in soils and sediments where it is abundant due to geological or anthropogenic sources.
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Affiliation(s)
- Owen W Duckworth
- Department of Soil Science, North Carolina State University, Raleigh, NC 27695-7619, USA.
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Kruft BI, Harrington JM, Duckworth OW, Jarzęcki AA. Quantum mechanical investigation of aqueous desferrioxamine B metal complexes: Trends in structure, binding, and infrared spectroscopy. J Inorg Biochem 2013; 129:150-61. [DOI: 10.1016/j.jinorgbio.2013.08.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 08/23/2013] [Accepted: 08/26/2013] [Indexed: 10/26/2022]
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Deicke M, Bellenger JP, Wichard T. Direct quantification of bacterial molybdenum and iron metallophores with ultra-high-performance liquid chromatography coupled to time-of-flight mass spectrometry. J Chromatogr A 2013; 1298:50-60. [DOI: 10.1016/j.chroma.2013.05.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 04/30/2013] [Accepted: 05/02/2013] [Indexed: 10/26/2022]
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