Control of sulfidogenesis through bio‐oxidation of H₂S coupled to (per)chlorate reduction

Abstract

We investigated H2S attenuation by dissimilatory perchlorate-reducing bacteria (DPRB). All DPRB tested oxidized H2S coupled to (per)chlorate reduction without sustaining growth. H2S was preferentially utilized over organic electron donors resulting in an enriched (34S)-elemental sulfur product. Electron microscopy revealed elemental sulfur production in the cytoplasm and on the cell surface of the DPRB Azospira suillum. Based on our results, we propose a novel hybrid enzymatic-abiotic mechanism for H2S oxidation similar to that recently proposed for nitrate-dependent Fe(II) oxidation. The results of this study have implications for the control of biosouring and biocorrosion in a range of industrial environments.

Mechanisms of direct inhibition of the respiratory sulfate-reduction pathway by (per)chlorate and nitrate

“…The results of these studies in combination with our previous work Gregoire et al, 2014) signify that perchlorate amendment is a promising new strategy for control of sulfidogenesis in industrial systems. These studies further indicate that sulfidogenesis inhibition in complex ecosystems by (per)chlorate is multifaceted.…”

“…We demonstrate that nitrate is antagonistic to (per)chlorate inhibition in batch systems and resistance is cross-inducible implying that these compounds share at least one common target or mechanism of resistance. In combination with our previous studies Gregoire et al, 2014) these studies indicate the great potential for (per)chlorate as an attractive alternative technology for controlling sulfidogenesis in industrial ecosystems. Because of its unique physical and chemical properties relative to chlorate (Motzer 2001;Urbansky 2002;Coates and Achenbach 2004;Engelbrektson et al, 2014), perchlorate is seen as a more practical solution for industrial application.…”

“…These studies further indicate that sulfidogenesis inhibition in complex ecosystems by (per)chlorate is multifaceted. In addition to thermodynamic preference (E o ' ¼ þ 797 mV for the biological couple of ClO 4 À /Cl À ) relative to sulfate reduction (E o ' ¼ À 217 mV) and the ability of all dissimilatory (per)chlorate-reducing microorganism tested to innately oxidize H 2 S coupled to (per)chlorate respiration (Gregoire et al, 2014), these studies demonstrate that (per)chlorate is also directly and specifically inhibitory of SRM. As this inhibitor targets the central sulfate-respiratory pathway, which is highly conserved across all SRM regardless of phylogenetic affiliation, inhibition should be universal.…”

“…Perchlorate and chlorate, collectively (per)chlorate, represent an attractive alternative to nitrate as inhibitors of sulfide production Gregoire et al, 2014). As with nitrate, both direct and indirect inhibition mechanisms are possible.…”

“…Alternatively, indirect inhibition of sulfidogenesis by (per)chlorate can proceed by thermodynamic preference of these compounds as respiratory electron acceptors (Coates and Achenbach 2004;Engelbrektson et al, 2014) and inhibition of SRM by biogenic reactive chlorine and oxygen species. Furthermore, all dissimilatory (per)chlorate-reducing microorganisms tested innately coupled H 2 S oxidation to (per)chlorate reduction (Bruce et al, 1999), producing elemental sulfur as an inert primary end product (Gregoire et al, 2014) thus removing the principle cause of souring.…”