Sulfur oxidation to sulfate coupled with electron transfer to electrodes by Desulfuromonas strain TZ1

Abstract

Microbial oxidation of elemental sulfur with an electrode serving as the electron acceptor is of interest because this may play an important role in the recovery of electrons from sulfidic wastes and for current production in marine benthic microbial fuel cells. Enrichments initiated with a marine sediment inoculum, with elemental sulfur as the electron donor and a positively poised (+300 mV versus Ag/AgCl) anode as the electron acceptor, yielded an anode biofilm with a diversity of micro-organisms, including Thiobacillus, Sulfurimonas, Pseudomonas, Clostridium and Desulfuromonas species. Further enrichment of the anode biofilm inoculum in medium with elemental sulfur as the electron donor and Fe(III) oxide as the electron acceptor, followed by isolation in solidified sulfur/Fe(III) medium yielded a strain of Desulfuromonas, designated strain TZ1. Strain TZ1 effectively oxidized elemental sulfur to sulfate with an anode serving as the sole electron acceptor, at rates faster than Desulfobulbus propionicus, the only other organism in pure culture previously shown to oxidize S° with current production. The abundance of Desulfuromonas species enriched on the anodes of marine benthic fuel cells has previously been interpreted as acetate oxidation driving current production, but the results presented here suggest that sulfur-driven current production is a likely alternative.

Correlation of the Electrochemical Kinetics of High‐Salinity‐Tolerant Bioanodes with the Structure and Microbial Composition of the Biofilm

“…The presence of the Desulfuromonas genus was not surprising, as these bacteria had already been identified as electroactive in the pioneering MFC studies. [43] This genus has been found to be dominant on bioanodes formed from marine sediments [44,45] and other different types of inoculum, such as paper-mill effluents. [46] Desulfuromonas acetoxidans is known to reduce Fe III oxides through outer-membrane type-C cytochromes [47] and it has been implemented in MFCs.…”

Synergic system between photovoltaic module and microbial fuel cell with simultaneous pollution control

“…Recently it was shown that Desulfuromonas species are capable to S° oxidation coupled to electron transfer to electrodes which has important implications for the interpretation of the function of microbial communities colonizing anodes and harvesting electricity from marine sediments 10 . Desulfuromonas species are often the most abundant species in the biofilms of marine sediment fuel cells 10,[22][23][24][25] . It was previously assumed that the primary role of these organisms was the oxidation of acetate coupled to current production.…”

“…However, by setting the anode potential at +300 mV vs. Ag/AgCl, the abstraction of electrons from sulfur by sulfur-oxidizing species forms sulfate that can be reduced again to H2S by sulfate-reducing microorganisms, such as Desulfovibrio species that belong to sulfur cycle bacteria 10 . Recently it was shown that Desulfuromonas species are capable to S° oxidation coupled to electron transfer to electrodes which has important implications for the interpretation of the function of microbial communities colonizing anodes and harvesting electricity from marine sediments 10 . Desulfuromonas species are often the most abundant species in the biofilms of marine sediment fuel cells 10,[22][23][24][25] .…”

“…Recently it was determined that despite H2S generation as a result of S 0 -reduction, this bacterium can also oxidize elemental sulfur to sulfite and sulfate with an electrode serving as the electron acceptor 10 . Since sulfur can accumulate on anodes from the abiotic oxidation of sulfide it shows the possibility of continuous simultaneous carrying of opposite stages of sulfur cycle in the anode chamber of MFC by activity of only one genus of bacterium.…”

Interconnection between tricarboxylic acid cycle and energy generation in microbial fuel cell performed by desulfuromonas acetoxidans IMV B-7384

“…Since the electron transfer mechanisms so far observed in BESs resemble closely to the mechanisms investigated for dissimilatory metal reducing microorganisms 4 , D. acetoxidans is very promising anode biocatalyst for MFC that is not investigated enough presently. Recently it was shown that despite hydrogen sulfide generation as a result of S 0 -reduction, this bacterium can also oxidize elemental sulfur to sulfite and sulfate with an electrode serving as the electron acceptor 9 . Since sulfur can accumulate on anodes from the abiotic oxidation of sulfide it shows the possibility of continuous simultaneous carrying of opposite stages of sulfur cycle in the anode chamber of MFC by activity of only one genus of bacterium.…”