What Do We Really Know about the Role of Microorganisms in Iron Sulfide Mineral Formation?

Abstract

Iron sulfide mineralization in low-temperature systems is a result of biotic and abiotic processes, though the delineation between these two modes of formation is not always straightforward. Here we review the role of microorganisms in the precipitation of extracellular iron sulfide minerals. We summarize the evidence that links sulfur-metabolizing microorganisms and sulfide minerals in nature and we present a critical overview of laboratory-based studies of the nucleation and growth of iron sulfide minerals in microbial cultures. We discuss whether biologically derived minerals are distinguishable from abiotic minerals, possessing attributes that are uniquely diagnostic of biomineralization. These inquiries have revealed the need for additional thorough, mechanistic and high-resolution studies to understand microbially mediated formation of a variety of sulfide minerals across a range of natural environments.

Biogenic Iron Sulfide Nanoparticles to Enable Extracellular Electron Uptake in Sulfate‐Reducing Bacteria

“…This energy acquisition strategy does not require organic electron donors and would therefore be especially effective, besides the OMCs‐mediated EEU, in sediments containing highly reductive minerals. These results further the understanding and provide novel insights into the interplay and evolution of biogeochemical cycles including iron, sulfur, and carbon . Furthermore, our findings have implications for microbial iron corrosion .…”

Nanoparticulate Nickel-Hosting Phases in Sulfidic Environments: Effects of Ferrous Iron and Bacterial Presence on Mineral Formation Mechanism and Solid-Phase Nickel Distribution

“…The d-spacings are consistent with those of millerite, although we cannot rule out the presence of other phases such as α-NiS, godlevskite and polydymite (Supplementary Table S1). The average sulfur-to-metal ratios for these spheroids are slightly above 1.00 (Table 2), which is likely due to excess sulfur adsorption to nanoparticles' surfaces Huang et al, 2010;Picard et al, 2016). High-resolution TEM images reveal the polyphasic nature (as defined by French et al, 2012) of the early-stage Ni-sulfide spheroids, in that they contain crystalline areas ∼1-3 nm in size within an amorphous matrix (Figure 2b).…”

“…Spot EDS analysis used beam sizes of 20-500 nm in diameter, while mapping analysis was conducted in scanning-TEM mode with a resolution of ∼10 nm. The inherent error of ≤7% for the standardless EDS analysis method (Newbury and Ritchie, 2014), compounded by the possibility of sulfur adsorption onto the nanoparticles' surface Huang et al, 2010;Picard et al, 2016) may contribute to the deviation of the measured elemental ratios from the real ones, especially for nanoparticles with substantially high surface areas. Thus, the EDS data were considered semi-quantitative.…”

“…The variables tested in this study are chosen so as to capture the biogeochemical diversity of potential Ni precipitation sites in natural settings. For example, SRB is known to be a primary producer of sulfide in low temperature environments and are expected to be intimately associated with metal sulfide precipitation (Picard et al, 2016). Experiments, however, have shown that even when SRB are present, a significant fraction of the metals may still be precipitated in the bulk solution away from the cell surfaces (Picard et al, 2018;Stanley and Southam, 2018).…”

The use of dithiothreitol for the quantitative analysis of elemental sulfur concentrations and isotopes in environmental samples

“…Microbial sulfate reduction is responsible for a significant portion of organic matter oxidation in marine sediments (Jørgensen 1982). In marine systems, up to 90% of the hydrogen sulfide produced can be reoxidized to sulfur intermediate compounds and eventually to sulfate by oxidation with molecular oxygen, iron(III), nitrate, or other oxidants via multiple oxidation pathways (Jørgensen, 1982;Zopfi et al, 2004;Picard et al, 2016). In and is also an important part of pyritization pathways (Thamdrup et al, 1994a;Rickard et al, 2017).…”