sulfuroxidizers

Sulfuroxidizers are microorganisms that obtain energy by oxidizing reduced sulfur compounds to sulfate. The majority are chemoautotrophs that fix carbon dioxide and rely on inorganic substrates for energy rather than organic matter. In oxygen-rich environments, oxygen commonly serves as the terminal electron acceptor, but some sulfuroxidizers can use nitrate or other acceptors in low-oxygen or anoxic zones, enabling sulfide oxidation in diverse redox settings.

Metabolic pathways used to oxidize sulfur compounds include the Sox (sulfur oxidation) multienzyme system, which processes thiosulfate and related species, and the reverse dissimilatory sulfite reductase (rDSR) pathway, which operates on sulfide or elemental sulfur in certain lineages. Some sulfuroxidizers accumulate elemental sulfur or form intracellular sulfur globules as intermediates. Taxonomically, they span several bacterial groups—especially among the Proteobacteria—as well as sulfur-oxidizing archaea that inhabit extreme environments. Common marine representatives include filamentous Beggiatoa and the stalked bacteria Thiomargarita, as well as free-living Sulfurovum and Sulfurimonas in vent and seep settings; freshwater and soil lineages include Thiobacillus and related taxa.

Ecologically, sulfuroxidizers contribute to the sulfur cycle by converting reduced sulfur to sulfate, supporting primary production in dark or sulfide-rich habitats and linking energy flow to other organisms. They influence sulfur chemistry, pH, and metal cycling in natural and engineered systems. In wastewater treatment and bioreactors, sulfur-oxidizing bacteria are used to remove sulfide odors and oxidize reduced sulfur species, often in combination with oxygen or nitrate supply to optimize performance.