Characterizing Microbial Diversity and the Potential for Metabolic Function at −15 °C in the Basal Ice of Taylor Glacier, Antarctica

Biology

Shawn M. Doyle²  Scott N. Montross¹  Mark L. Skidmore¹ 

[1] Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA; E-Mails:;Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA; E-Mail:

关键词: Antarctica;    basal ice;    subzero metabolism;    microbial survival;   

DOI  :  10.3390/biology2031034

来源: mdpi

【 摘 要 】

Measurement of gases entrapped in clean ice from basal portions of the Taylor Glacier, Antarctica, revealed that CO₂ ranged from 229 to 328 ppmv and O₂ was near 20% of the gas volume. In contrast, vertically adjacent sections of the sediment laden basal ice contained much higher concentrations of CO₂ (60,000 to 325,000 ppmv), whereas O₂ represented 4 to 18% of the total gas volume. The deviation in gas composition from atmospheric values occurred concurrently with increased microbial cell concentrations in the basal ice profile, suggesting that in situ microbial processes (i.e., aerobic respiration) may have altered the entrapped gas composition. Molecular characterization of 16S rRNA genes amplified from samples of the basal ice indicated a low diversity of bacteria, and most of the sequences characterized (87%) were affiliated with the phylum, Firmicutes. The most abundant phylotypes in libraries from ice horizons with elevated CO₂ and depleted O₂ concentrations were related to the genus Paenisporosarcina, and 28 isolates from this genus were obtained by enrichment culturing. Metabolic experiments with Paenisporosarcina sp. TG14 revealed its capacity to conduct macromolecular synthesis when frozen in water derived from melted basal ice samples and incubated at −15 °C. The results support the hypothesis that the basal ice of glaciers and ice sheets are cryospheric habitats harboring bacteria with the physiological capacity to remain metabolically active and biogeochemically cycle elements within the subglacial environment.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.