Oremland Ronald S, Kulp Thomas R, Blum Jodi Switzer, Hoeft Shelley E, Baesman Shaun, Miller Laurence G, Stolz John F
U.S. Geological Survey, ms 480, 345 Middlefield Road, Menlo Park, CA 94025, USA.
Science. 2005 May 27;308(5726):1305-8. doi: 10.1126/science.1110832.
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.
瑟尔斯湖是一个盐饱和的碱性卤水湖，异常富含有毒元素砷。随着沉积物深度的增加，砷的形态从砷酸盐[As(V)]转变为亚砷酸盐[As(III)]。经培养的缺氧沉积物浆液表现出异化型As(V)还原酶活性，该活性受到H2或硫化物的显著刺激，而好氧浆液具有快速的As(III)氧化酶活性。从沉积物中分离出一种厌氧、极端嗜盐碱细菌，它通过As(V)呼吸生长，以乳酸盐或硫化物作为电子供体。因此，在瑟尔斯湖发生了一个完整的砷生物地球化学循环，部分由无机电子供体驱动。
