Microbial diversity and activity in hypersaline high Arctic spring channels

Abstract

Lost Hammer (LH) spring is a unique hypersaline, subzero, perennial high Arctic spring arising through thick permafrost. In the present study, the microbial and geochemical characteristics of the LH outflow channels, which remain unfrozen at C-18°C and are more aerobic/ less reducing than the spring source were examined and compared to the previously characterized spring source environment. LH channel sediments contained greater microbial biomass (*100-fold) and greater microbial diversity reflected by the 16S rRNA clone libraries. Phylotypes related to methanogenesis, methanotrophy, sulfur reduction and oxidation were detected in the bacterial clone libraries while the archaeal community was dominated by phylotypes most closely related to THE ammonia-oxidizing Thaumarchaeota. The cumulative percent recovery of 14 Cacetate mineralization in channel sediment microcosms exceeded *30% and *10% at 5 and -5°C, respectively, but sharply decreased at -10°C( B1%). Most bacterial isolates (Marinobacter, Planococcus, and Nesterenkonia spp.) were psychrotrophic, halotolerant, and capable of growth at -5°C. Overall, the hypersaline, subzero LH spring channel has higher microbial diversity and activity than the source, and supports a variety of niches reflecting the more dynamic and heterogeneous channel environment.

Defining the Functional Potential and Active Community Members of a Sediment Microbial Community in a High-Arctic Hypersaline Subzero Spring

“…Other Arctic cold springs, on Ellesmere Island in the Canadian high Arctic and on the Norwegian highArctic Svalbard archipelago, have been reported (12-14), although the discharges from these springs are not subzero. Viable microbial communities have been described for all of these Arctic springs (3,4,7,8,(13)(14)(15).The Lost Hammer (LH) Spring, located in the central west region of AHI (79°7=N, 90°21=W) is the coldest and saltiest of all Arctic springs described to date. LH is characterized by a perennial hypersaline (24%) discharge at subzero temperatures (ϳϪ5°C) flowing to the surface through a hollow, 2-m-high cone-shaped salt tufa structure.…”

“…ryoenvironments are defined as permanently subzero or frozen environments, such as permafrost, glaciers, ice sheets, multiyear sea ice, high-elevation Antarctic dry valleys, and some cold saline springs (1)(2)(3)(4)(5)(6). Microorganisms inhabiting cryoenvironments must face the challenges of subzero temperatures, low water activity, and, often, high solute concentrations to sustain their viability.…”

“…Microorganisms inhabiting cryoenvironments must face the challenges of subzero temperatures, low water activity, and, often, high solute concentrations to sustain their viability. The cold saline springs on Axel Heiberg Island (AHI) in the Canadian high Arctic discharge through 500 to 600 m of thick permafrost, maintain a liquid state at subzero temperatures, and offer a unique opportunity to assess microbial adaptations to extremes of both high salinity and subzero temperatures (3,4,(7)(8)(9). These springs occur in an area with an average annual air temperature of Ϫ15°C, reaching below Ϫ40°C during the winter months, and probably originate from subpermafrost groundwater flow through carboniferous evaporites in areas of diapiric uplift on AHI (10,11).…”

“…Other Arctic cold springs, on Ellesmere Island in the Canadian high Arctic and on the Norwegian highArctic Svalbard archipelago, have been reported (12)(13)(14), although the discharges from these springs are not subzero. Viable microbial communities have been described for all of these Arctic springs (3,4,7,8,(13)(14)(15).…”

“…During the summer months, the spring waters empty from the dome structure, partially exposing the spring sediments to ambient conditions; however, the sediments remain anoxic and highly reducing. Continuous gas emissions from the spring indicate a thermogenic methane source underlying LH (3,4). On the basis of these properties, this spring is considered a significant astrobiology analogue site (15,16) for possible habitats currently present on Mars and the cold moons Europa and Enceladus.…”