title: High rates of sulfate reduction in a low-sulfate hot spring microbial mat are driven by a low level of diversity of sulfate-respiring microorganisms.
abstract: The importance of sulfate respiration in the microbial mat found in the low-sulfate thermal outflow of Mushroom Spring in Yellowstone National Park was evaluated using a combination of molecular, microelectrode, and radiotracer studies. Despite very low sulfate concentrations, this mat community was shown to sustain a highly active sulfur cycle. The highest rates of sulfate respiration were measured close to the surface of the mat late in the day when photosynthetic oxygen production ceased and were associated with a Thermodesulfovibrio-like population. Reduced activity at greater depths was correlated with novel populations of sulfate-reducing microorganisms, unrelated to characterized species, and most likely due to both sulfate and carbon limitation.
authors.affiliation: Department of Microbiology and NASA Astrobiology Institute, University of Washington, Seattle, Washington 98195, USA. jdillon@csulb.edu
authors.forename: Jesse G
authors.initials: JG
authors.lastname: Dillon
authors.forename: Susan
authors.initials: S
authors.lastname: Fishbain
authors.forename: Scott R
authors.initials: SR
authors.lastname: Miller
authors.forename: Brad M
authors.initials: BM
authors.lastname: Bebout
authors.forename: Kirsten S
authors.initials: KS
authors.lastname: Habicht
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Webb
authors.forename: David A
authors.initials: DA
authors.lastname: Stahl
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002244:Carbon / Q000737:chemistry / Q000378:metabolism; D045482:Hot Springs / Q000737:chemistry / Q000382:microbiology*; D006862:Hydrogen Sulfide / Q000737:chemistry / Q000378:metabolism; D050885:Hydrogensulfite Reductase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010802:Phylogeny; D013431:Sulfates / Q000737:chemistry / Q000378:metabolism*; D013455:Sulfur / Q000737:chemistry / Q000378:metabolism; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D013431:Sulfates; D013455:Sulfur; D002244:Carbon; D050885:Hydrogensulfite Reductase; D010100:Oxygen; D006862:Hydrogen Sulfide