Monofluorophosphate Is a Selective Inhibitor of Respiratory Sulfate-Reducing Microorganisms

Abstract

Despite the environmental and economic cost of microbial sulfidogenesis in industrial operations, few compounds are known as selective inhibitors of respiratory sulfate reducing microorganisms (SRM), and no study has systematically and quantitatively evaluated the selectivity and potency of SRM inhibitors. Using general, high-throughput assays to quantitatively evaluate inhibitor potency and selectivity in a model sulfate-reducing microbial ecosystem as well as inhibitor specificity for the sulfate reduction pathway in a model SRM, we screened a panel of inorganic oxyanions. We identified several SRM selective inhibitors including selenate, selenite, tellurate, tellurite, nitrate, nitrite, perchlorate, chlorate, monofluorophosphate, vanadate, molydate, and tungstate. Monofluorophosphate (MFP) was not known previously as a selective SRM inhibitor, but has promising characteristics including low toxicity to eukaryotic organisms, high stability at circumneutral pH, utility as an abiotic corrosion inhibitor, and low cost. MFP remains a potent inhibitor of SRM growing by fermentation, and MFP is tolerated by nitrate and perchlorate reducing microorganisms. For SRM inhibition, MFP is synergistic with nitrite and chlorite, and could enhance the efficacy of nitrate or perchlorate treatments. Finally, MFP inhibition is multifaceted. Both inhibition of the central sulfate reduction pathway and release of cytoplasmic fluoride ion are implicated in the mechanism of MFP toxicity.

System-Wide Adaptations of Desulfovibrio alaskensis G20 to Phosphate-Limited Conditions

“…MFP is a selective inhibitor of the sulfate reduction pathway and also releases cytoplasmic fluoride ion, inhibiting enzymes that rely on hydroxide ion for catalysis (e.g. enolase) [51]. Therefore, we hypothesize that treatments of sulfate reducing microbes with MFP or THPS may be more efficient during phosphate limitation.…”

“…We also used MEV to compare the fitness scores of important genes measured in our study to the fitness scores measured for the same genes under different growth and stress conditions. The results of previous experiments were downloaded from the microbesonline.org database [36, 49–51]. We used OperonDB http://operondb.cbcb.umd.edu/cgi-bin/operondb/pairs.cgi?genome_id=329 and microbesonline.org to determine whether genes occurred in the same operon.…”

Arsenic Methylation Dynamics in a Rice Paddy Soil Anaerobic Enrichment Culture

“…The mechanism for molybdate and monofluorophosphate inhibition of sulfate reduction is the same: reaction between molybdate or monofluorophosphate and ATP interferes with the first step in the DSR pathway, the formation of adenosine 5′-phosphosulfate (APS) from ATP and SO 4 2− . The fact that addition of recommended concentrations 36 of molybdate versus monofluorophosphate had divergent effects on As methylation suggests that the mechanism was not solely related to the inhibition of DSR. Higher molybdate concentrations caused greater reductions in methylation efficiency (Figure 2), suggesting a dose-dependent effect of molybdate on arsenic methylation.…”

Diversity and Composition of Sulfate-Reducing Microbial Communities Based on Genomic DNA and RNA Transcription in Production Water of High Temperature and Corrosive Oil Reservoir

“…In spite of success with nitrate to control or prevent souring, problems exist for ineffectiveness in low-temperature oil reservoirs as a result of emergence of microbial zone (Callbeck et al, 2011). Recently, perchlorate and monofluorophosphate have been demonstrated as effective inhibitors of SRM (Carlson et al, 2015a,b). Perchlorate is effective in laboratory tests and also inhibits the sulfate reduction by Archaeoglobus (Engelbrektson et al, 2014).…”