Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA.
Environ Microbiol Rep. 2011 Dec;3(6):774-82. doi: 10.1111/j.1758-2229.2011.00298.x. Epub 2011 Oct 18.
The habitability of icy environments may be limited by low temperature, low nutrient concentrations, high solute concentrations and the physical ice matrix. The basal ice of ice sheets and glaciers contains sediments that may be a source of nutrients for microbial activity. Here we quantify microbial respiration and active cell populations of Antarctic glacial isolates Paenisporosarcina sp. B5 and Chryseobacterium sp. V3519-10 in laboratory ices with abundant nutrients at temperatures from -4°C to -33°C. At all temperatures, initial high rates of metabolism were followed by lower rates suggestive of a non-reproductive metabolic state such as maintenance or dormancy. Metabolism was sustained by viable cells as quantified via culturability, CTC reduction and LIVE/DEAD staining. Respiration rates based on active cell populations did not correspond to rates representative of reproductive growth from the literature, but suggested lower levels of metabolism. Our data demonstrated that bacteria actively respired acetate in polycrystalline ice with abundant nutrients despite low temperatures and the physical ice matrix. Our results suggest that the debris-rich basal ice that exists at temperatures just below the freezing point and underlies portions of both the Greenland and Antarctic ice sheets represents a significant potential habitat for metabolically active microbial communities.
冰冷环境的宜居性可能受到低温、低营养浓度、高溶质浓度和物理冰基质的限制。冰盖和冰川的基底层冰含有可能是微生物活动养分来源的沉积物。在这里，我们在温度为-4°C 至-33°C 的富含营养物质的实验室冰中，定量测定了南极冰川分离株 Paenisporosarcina sp. B5 和 Chryseobacterium sp. V3519-10 的微生物呼吸作用和活性细胞群体。在所有温度下，最初的高代谢率之后是较低的代谢率，这表明存在非生殖代谢状态，如维持或休眠。代谢通过可培养性、CTC 还原和 LIVE/DEAD 染色来量化的存活细胞得以维持。基于活性细胞群体的呼吸率与文献中代表生殖生长的速率不一致，但表明代谢水平较低。我们的数据表明，尽管温度低且存在物理冰基质，但在富含营养物质的多晶冰中，细菌仍能积极地呼吸乙酸盐。我们的研究结果表明，在接近冰点的温度下存在富含碎片的基底层冰，并且存在于格陵兰和南极冰盖的部分地区，这代表了具有代谢活性微生物群落的重要潜在栖息地。
