A microbial arsenic cycle in a salt-saturated, extreme environment.
Searles Lake is a salt-saturated, alkaline brine unusually rich in the toxic element arsenic. Arsenic speciation changed from arsenate [As(V)] to arsenite [As(III)] with sediment depth. Incubated anoxic sediment slurries displayed dissimilatory As(V)-reductase activity that was markedly stimulated by H2 or sulfide, whereas aerobic slurries had rapid As(III)-oxidase activity. An anaerobic, extremely haloalkaliphilic bacterium was isolated from the sediment that grew via As(V) respiration, using either lactate or sulfide as its electron donor. Hence, a full biogeochemical cycle of arsenic occurs in Searles Lake, driven in part by inorganic electron donors.
Oremland
Ronald S
RS
U.S. Geological Survey, ms 480, 345 Middlefield Road, Menlo Park, CA 94025, USA. roremlan@usgs.gov
Kulp
Thomas R
TR
Blum
Jodi Switzer
JS
Hoeft
Shelley E
SE
Baesman
Shaun
S
Miller
Laurence G
LG
Stolz
John F
JF
D000332:Aerobiosis; D000693:Anaerobiosis; D001149:Arsenates / Q000378:metabolism*; D018053:Arsenites / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism*; D001639:Bicarbonates / Q000378:metabolism; D002140:California; D017753:Ecosystem; D004579:Electron Transport; D020459:Genes, rRNA; D019015:Geologic Sediments / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D012492:Salts; D012965:Sodium Chloride; D013440:Sulfides / Q000378:metabolism; D014867:Water / Q000737:chemistry; D014871:Water Microbiology
D001149:Arsenates; D018053:Arsenites; D001639:Bicarbonates; D012492:Salts; D013440:Sulfides; D014867:Water; D019344:Lactic Acid; D012965:Sodium Chloride; C015001:arsenite; C025657:arsenic acid