New Mobilization Pathway of Antimonite: Thiolation and Oxidation by Dissimilatory Metal-Reducing Bacteria via Elemental Sulfur Respiration

Abstract

Antimony (Sb) mobilization is widely explored with dissimilatory metal-reducing bacteria (DMRB) via microbial iron­(III)-reduction. Here, our study found a previously unknown pathway whereby DMRB release adsorbed antimonite (SbIII-O) from goethite via elemental sulfur (S0) respiratory reduction under mild alkaline conditions. We incubated SbIII-O-loaded goethite with Shewanella oneidensis MR-1 in the presence of S0 at pH 8.5. The incubation results showed that MR-1 reduced S0 instead of goethite, and biogenic sulfide induced the formation of thioantimonite (SbIII-S). SbIII-S was then oxidized by S0 to mobile thioantimonate (SbV-S), resulting in over fourfold greater Sb release to water compared with the abiotic control. SbIV-S was identified as the intermediate during the oxidation process by Fourier transform ion cyclotron resonance mass spectrometry and electron spin resonance analysis. The existence of SbIV-S reveals that the oxidation of SbIII-S to SbV-S follows a two-step consecutive one-electron transfer from Sb to S atoms. SbV-S then links with SbIII-S by sharing S atoms and inhibits SbIII-S polymerization and SbIII 2S3 precipitation like a “capping agent”. This study clarifies the thiolation and oxidation pathway of SbIII-O to SbV-S by S0 respiration and expands the role of DMRB in the fate of Sb.

Arsenite S-Adenosylmethionine Methyltransferase Is Responsible for Antimony Biomethylation in Nostoc sp. PCC7120

“…To examine whether the substrate for NsArsM is Sb(OH) 3 or Sb(GS) 3 , Raman spectra were collected as shown in Figure 2C. Two Raman shifts at 319 and 352 cm −1 were observed when Sb(III)-O was mixed with GSH for 1 min and assigned as Sb−S stretching vibrations of polymeric Sb(III)-S. 39 In agreement with a previous study that GSH exists in millimolar levels in cytosol, 40,41 our Raman results suggest the readily formation of Sb(III)-GSH complexes as the NsArsM substrate. Meanwhile, the Sb−C bond in methylated Sb was evidenced by surface-enhanced Raman scattering (SERS) spectroscopy (Figure 2D), where a new peak at 532 cm −1 was clearly resolved after 2 h incubation, which is due to Sb−C vibrations.…”

“…Consistent with our results, As(GS) 3 , a complex of GSH and As(III), has been reported as the preferred substrate for ArsM protein. 38 Considering that the thiol groups in GSH exhibit a strong preference for Sb(III) relative to As(III), 39 Sb(III) would readily form complexes with GSH, and the resulting Sb(GS) 3 binds to NsArsM protein.…”

Fate of antimony contamination generated by road traffic – A focus on Sb geochemistry and speciation in stormwater ponds

“…Thioantimonate species have been designated as potential intermediates of these sulphidation reactions, having particular consequences on Sb mobility for instance by limiting Sb affinity to iron oxides (Ye et al, 2019(Ye et al, , 2021. The presence of minor amounts of such thio-Sb forms, including within the solid phase, could not be excluded since XANES spectra of sorbed thio-Sb at the Sb K-edge should contribute in between the Sb-O and Sb-S species.…”

Simulated-sunlight-driven Cr(vi) reduction on a type-II heterostructured Sb2S3/CdS photocatalyst

“…1(b), the bare Sb 2 S 3 shows two weak characteristic peaks at Raman Environmental Science: Nano Paper shifts of 280.4 cm −1 and 302.3 cm −1 , which correspond to the Sb-S stretching vibration of the A g -symmetry group on the surface of Sb 2 S 3 . 26 After the CdS NP anchoring, two strong characteristic peaks appear at Raman shifts of 292 cm −1 and 592 cm −1 , which can be assigned to the intense first-order longitudinal optical (1-LO) phonon and second-order (2-LO) overtone of the cubic CdS lattice. 27 This further supports the conclusion from XRD analysis.…”