A universal assay for the detection of siderophore activity in natural waters
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Siderophores, a family of biogenic metal chelating agents, play critical roles in the biogeochemical cycling of Fe and other metals by facilitating their solubilization and uptake in circumneutral to alkaline oxic environments. However, because of their small concentrations (ca. nM) and large number of molecular structures, siderophore detection and quantification in environmental samples requires specialized equipment and expertise, and often requires pre-concentration of samples, which may introduce significant bias. The “universal” CAS assay, which was originally designed for use in bacterial cultures, quantifies the iron chelating function of a pool of siderophores but only at concentrations (>2 µM) well above the concentrations estimated to be present in marine, freshwater, and soil samples. In this manuscript, we present a high sensitivity modification of this universal assay (HS-CAS) suitable for detecting and quantifying siderophore activity in the nM concentration range, allowing for direct quantitation of siderophore reactivity in transparent aqueous samples.
KeywordsSiderophores Environmental assay Metal uptake Biogeochemistry
We thank Lauren Saal and Tyler Sowers for assistance in method development and sampling. We thank the North Carolina Agricultural Research Service (02440) for support.
- Almaraz N, Whitaker AH, Andrews MY, Duckworth OW (in review) Assessing biomineral formation by iron-oxidizing bacteria in a circumneutral creekGoogle Scholar
- Brausam A, van Eldik R (2012) Advances in the mechanistic understanding of selected reactions of transition metal polyaminecarboxylate complexes. In: van Rudi E, Ivana I-B (eds) Advances in inorganic chemistry, vol 64. Academic Press, Cambridge, pp 141–181. doi:10.1016/B978-0-12-396462-5.00005-2 Google Scholar
- Frausto da Silva JRR, Williams RJP (1991) The biological chemistry of the elements. Clarendon Press, OxfordGoogle Scholar
- Haselwandter K, Winkelmann G (1998) Identification and characterization of siderophores of mycorrhizal fungi. Springer Lab Manual Series; Mycorrhiza manual. Springer, BerlinGoogle Scholar
- Machuca A, Navias D, Milagres AMF, Chavez D, Guillen Y (2014) Effects of metal ions (Cd2+, Cu2+, Zn2+) on the growth and chelating-compound production of three ectomycorrhizal fungi. Interciencia 39:221–227Google Scholar
- Moberg M, Holmstrom SJ, Lundstrom US, Markides KE (2003) Novel approach to the determination of structurally similar hydroxamate siderophores by column-switching capillary liquid chromatography coupled to mass spectrometry. J Chromatogr A 1020:91–97. doi:10.1016/s0021-9673(03)01236-6 CrossRefPubMedGoogle Scholar
- Ribas X, Salvado V, Valiente M (1989) The chemistry of iron in biosystems. II: a hydrolytic model of the complex formation between iron(III) and citric acid in aqueous solutions. J Chem Res 1989:2533–2553Google Scholar
- Sowers TD, Harrington JM, Polizzotto ML, Duckworth OW (2016) Sorption of arsenic to biogenic iron (oxyhydr)oxides produced in circumneutral environments. Geochim Cosmochim Acta (in press)Google Scholar
- Upase AB, Zade AB, Kalbende PP (2011) Spectrophotometric microdetermination of thorium(IV) and uranium(VI) with chrome azurol-s in presence of cationic surfactant. J Chem 8:1132–1141Google Scholar
- van der Helm D, Winkelmann G (1994) Hydroxamates and polycarboxylates as iron transport agents (siderophores) in fungi. In: Winkelmann G, Winge FR (eds) Metal ions in fungi. M. Dekker, New York, pp 39–98Google Scholar
- Wei G-Z (1992) A chemical tool for the detection of siderophores. Lamar University, BeaumontGoogle Scholar