Elemental Sulfur Disproportionation: pathways and application

Some microorganisms gain energy by disproportionating elemental sulfur, using it as both electron donor and acceptor and producing sulfate and sulfide. Because the reaction yields energy only when sulfide stays low, we developed a cultivation method that continuously strips sulfide by sparging cultures with N2/CO2, avoiding metal-oxide scavengers that hinder physiology and RNA work. With this approach we grew Desulfocapsa sulfexigens on sulfur or thiosulfate, collected RNA‑seq data, and combined expression patterns with product and thermodynamic analyses to propose a sulfur-disproportionation pathway. We also studied Acidianus sp. DS80, which appears to use alternative proteins and forms sulfate and later thiosulfate.