Coupled Abiotic and Biotic Sulfurization Processes during Microbial Sulfate Reduction with Alkyl Substrates

We here demonstrate that abiotic and biotic sulfurization processes can concomitantly occur during the degradation of alkyl substrates by microbial sulfate-reduction (MSR), and that sulfurization of OM can lead to the formation of OSC that, in return, can potentially fuels MSR. It can thus be envisaged that, in some circumstances, MSR can 1) counterbalance the apparent recalcitrance of OSC formed abiotically by metabolizing them further into cell biomass and/or other less recalcitrant OSC and, 2) decrease the content in OSC (and thus increase the quality) of the preserved OM/oil. The biogeochemical importance of such processes still needs to be evaluated. In addition to the enlargement of the panel of interactions that can occur during OM diagenesis in hydrocarbon-containing anoxic sediments and oil reservoirs, our study opens up new perspectives on mechanistic aspects involved in the sulfurization under natural conditions of organic compounds that are supposed not reactive with inorganic sulfur species.