Impact of high Fe-concentrations on microbial community structure and dissolved organics in hydrothermal plumes: an experimental study

Abstract

Iron (Fe) is an essential trace element for life. In the ocean, Fe can be exceptionally scarce and thus biolimiting or extremely enriched causing microbial stress. The ability of hydrothermal plume microbes to counteract unfavorable Fe-concentrations up to 10 mM is investigated through experiments. While Campylobacterota (Sulfurimonas) are prominent in a diverse community at low to intermediate Fe-concentrations, the highest 10 mM Fe-level is phylogenetically less diverse and dominated by the SUP05 clade (Gammaproteobacteria), a species known to be genetically well equipped to strive in high-Fe environments. In all incubations, Fe-binding ligands were produced in excess of the corresponding Fe-concentration level, possibly facilitating biological Fe-uptake in low-Fe incubations and detoxification in high-Fe incubations. The diversity of Fe-containing formulae among dissolved organics (SPE-DOM) decreased with increasing Fe-concentration, which may reflect toxic conditions of the high-Fe treatments. A DOM-derived degradation index (IDEG) points to a degradation magnitude (microbial activity) that decreases with Fe and/or selective Fe-DOM coagulation. Our results show that some hydrothermal microbes (especially Gammaproteobacteria) have the capacity to thrive even at unfavorably high Fe-concentrations. These ligand-producing microbes could hence play a key role in keeping Fe in solution, particularly in environments, where Fe precipitation dominates and toxic conditions prevail.

Microbial ecosystem assessment and hydrogen oxidation potential of newly discovered vent systems from the Central and South-East Indian Ridge

“…On the order level, W2 exhibited the highest abundances of Thiomicrospirales (18%) and Alteromonadales (22%, both Gammaproteobacteria) in this study, but no “ambient-water exclusive” orders were identified ( Supplementary Figure S1 ). The extraction of the 10 most abundant genera revealed an exceptionally high abundance of the gammaproteobacterial SUP05 cluster (16%), which has frequently been found in hydrothermal plume samples and was shown to be involved in sulfur and iron cycling ( Hansen et al, 2022 ; Zhou et al, 2023 ). However, the typically vent-associated Campylobacterales were missing in this sample ( Supplementary Figure S1 and Table 6 ).…”

New Insights into the Organic Complexation of Bioactive Trace Metals in the Global Ocean from the GEOTRACES Era

“…Speciation measurements around hydrothermal vents have revealed the importance of ligands in stabilizing hydrothermal supplies of dissolved metals for long distance transport (Sander and Koschinsky, 2011;Buck et al, 2015;Resing et al, 2015;Wang et al, 2019Wang et al, , 2021. This may reflect active production of ligands by hydrothermal plume communities to manage or access metals, in particular iron (Hansen et al, 2022). Sea ice melt may also contribute organic ligands to seawater (Lannuzel et al, 2015;Genovese et al, 2018;Arnone et al, 2023Arnone et al, , 2024.…”

A Comprehensive Evaluation of Heavy Metal Contaminations in Soils of Ohio and West Virginia and Cucurbitaceous Vegetables Grown in Respective Farms and Implications on Human Health

“…Our results showed that the farmlands in Meigs County might have been exposed to greater HM concentrations. These increased concentrations of HMs may affect the soil structure, plant growth, nutrient, and water uptake by impairing the primary root growth and root hair formation [30,31].…”

“…Additionally, substantial quantities of Ni and Cu metals were also found, indicating their contribution to overall pollution levels. Understanding the sources and mechanisms of these HMs' enrichment are critical for assessing the possible impact on soil health [31]. Moreover, these parameters can aid in planning risk mitigation strategies for HM contamination to minimize health hazards.…”