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Title: Thiosulfate oxidation by Thiomicrospira thermophila: Metabolic flexibility in response to ambient geochemistry

Previous studies of the stoichiometry of thiosulfate oxidation by colorless sulfur bacteria have failed to demonstrate mass balance of sulfur, indicating that unidentified oxidized products must be present. Here the reaction stoichiometry and kinetics under variable pH conditions during the growth of Thiomicrospira thermophila strain EPR85, isolated from diffuse hydrothermal fluids at the East Pacific Rise, is presented. At pH 8.0, thiosulfate was stoichiometrically converted to sulfate. At lower pH, the products of thiosulfate oxidation were extracellular elemental sulfur and sulfate. Here, we were able to replicate previous experiments and identify the missing sulfur as tetrathionate, consistent with previous reports of the activity of thiosulfate dehydrogenase. Tetrathionate was formed under slightly acidic conditions. Genomic DNA from T. thermophila strain EPR85 contains genes homologous to those in the Sox pathway ( soxAXYZBCDL), as well as rhodanese and thiosulfate dehydrogenase. No other sulfur oxidizing bacteria containing sox(CD)2 genes have been reported to produce extracellular elemental sulfur. If the apparent modified Sox pathway we observed in T. thermophila is present in marine Thiobacillus and Thiomicrospira species, production of extracellular elemental sulfur may be biogeochemically important in marine sulfur cycling.
Authors:
 [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [1] ;  [1]
  1. Washington Univ., St. Louis, MO (United States)
  2. Carnegie Inst. of Washington, Washington, DC (United States)
  3. Argonne National Lab. (ANL), Lemont, IL (United States); The Univ. of Chicago, Chicago, IL (United States)
  4. Rutgers Univ., New Brunswick, NJ (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Environmental Microbiology
Additional Journal Information:
Journal Volume: 18; Journal Issue: 9; Journal ID: ISSN 1462-2912
Publisher:
Wiley
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 58 GEOSCIENCES
OSTI Identifier:
1339997