Sulfur Metabolites Play Key System-Level Roles in Modulating Denitrification
Anne E. Otwell, Alex V. Carr, Erica L.‐W. Majumder, Maryann Ruiz, Regina L. Wilpiszeski, Linh Hoang, Bill Webb, Serdar Turkarslan, Sean M. Gibbons, Dwayne A. Elias, David A. Stahl, Gary Siuzdak, Nitin S. Baliga
Abstract
Nitrate-reducing bacteria (NRB) and sulfate-reducing bacteria (SRB) colonize diverse anoxic environments, including soil subsurface, groundwater, and wastewater. NRB and SRB compete for resources, and their interplay has major implications on the global cycling of nitrogen and sulfur species, with undesirable outcomes in some contexts. For instance, the removal of reactive nitrogen species by NRB is desirable for wastewater treatment, but in agricultural soils, NRB can drive the conversion of nitrates from fertilizers into nitrous oxide, a potent greenhouse gas. Similarly, the hydrogen sulfide produced by SRB can help sequester and immobilize toxic heavy metals but is undesirable in oil wells where competition between SRB and NRB has been exploited to suppress hydrogen sulfide production. By characterizing how reduced sulfur compounds inhibit growth and activity of NRB, we have gained systems-level and mechanistic insight into the interplay of these two important groups of organisms and drivers of their stratification in diverse environments.