Physiological Ecology of Microorganisms in Subglacial Lake Whillans

• DOI: 10.3389/fmicb.2016.01705
• Publication Date: 2016-10-27T07:10:54Z
• Authors: Trista J. Vick-Ma...; Andrew C. Mitchell; Amanda M. Achberger; Brent C. Christner; John E. Dore; Alexander B. Michaud; Jill A. Mikucki; Alicia M. Purcell; Mark L. Skidmore; John C. Priscu
• Keywords: Extreme environment

Subglacial microbial habitats are widespread in glaciated regions of our planet. Some these environments have been isolated from the atmosphere and sunlight for many thousands years. Consequently, ecosystem processes must rely on energy gained oxidation inorganic substrates or detrital organic matter. Lake Whillans (SLW) is one more than 400 subglacial lakes known to exist under Antarctic ice sheet; however, little about physiology energetics systems. When it was sampled through its 800 m thick cover 2013, SLW water column shallow (~2 deep), oxygenated, possessed sufficient concentrations C, N, P support growth. Here, we use a combination physiological assays models assess life SLW. In general, microorganisms grew slowly this energy-limited environment. Heterotrophic cellular carbon turnover times, calculated 3H-thymidine 3H-leucine incorporation rates, were long (60 500 days) while doubling times averaged 196 days. Inferred growth rates (average ~0.006 d-1) obtained same incubations at least an order magnitude lower those measured surface oligotrophic areas ocean. Low efficiency (8%) indicated that heterotrophic populations partition majority their demand maintenance rather Chemoautotrophic CO2-fixation exceeded C-demand by factor ~1.5. Aerobic respiratory activity associated with chemoautotrophic metabolism surpassed estimated supply oxygen SLW, implying could deplete oxygenated waters, resulting anoxia. We used thermodynamic calculations examine biogeochemical energetic consequences environmentally imposed switching between aerobic anaerobic metabolisms column. utilizing acetate formate as electron donors yielded less chemolithotrophic when terms density, which supports experimental results showed excess activity. The communities lake ecosystems provide important natural laboratories study behavior inhabiting cold, dark environments.