Sulfur Species as Redox Partners and Electron Shuttles for Ferrihydrite Reduction by Sulfurospirillum deleyianum

• DOI: 10.1128/aem.04220-13
• Publication Date: 2014-03-15T01:34:49Z
• Authors: Regina Lohmayer; Andreas Kappler; Tina Lösekann-Beh...; Britta Planer-Fri...
• Keywords: Ferrihydrite; Oxidation reduction

ABSTRACT Iron(III) (oxyhydr)oxides can represent the dominant microbial electron acceptors under anoxic conditions in many aquatic environments, which makes understanding mechanisms and processes regulating their dissolution transformation particularly important. In a previous laboratory-based study, it has been shown that 0.05 mM thiosulfate reduce 6 ferrihydrite indirectly via enzymatic reduction of to sulfide by sulfur-reducing bacterium Sulfurospirillum deleyianum , followed abiotic coupled reoxidation sulfide. Thiosulfate, elemental sulfur, polysulfides were proposed as reoxidized sulfur species functioning shuttles. However, exact transfer pathway remained unknown. Here, we present detailed analysis involved. Apart from thiosulfate, substoichiometric amounts sulfite, tetrathionate, sulfide, or also initiated reduction. The portion produced during ferrihydrite-dependent was about 10% total at maximum. main oxidation product attached iron mineral surface, indicates direct contact between microorganisms is necessary maintain process. Polysulfides not detected liquid phase. Minor found associated either with reaction identified rate determining. Cysteine, added source reducing agent, led therefore should be eliminated when redox reactions are investigated. Overall, could demonstrate large impact intermediate on biogeochemical transformations.