Comparison of Microbial Community Compositions of Two Subglacial Environments Reveals a Possible Role for Microbes in Chemical Weathering Processes

Abstract

Viable microbes have been detected beneath several geographically distant glaciers underlain by different lithologies, but comparisons of their microbial communities have not previously been made. This study compared the microbial community compositions of samples from two glaciers overlying differing bedrock. Bulk meltwater chemistry indicates that sulfide oxidation and carbonate dissolution account for 90% of the solute flux from Bench Glacier, Alaska, whereas gypsum/anhydrite and carbonate dissolution accounts for the majority of the flux from John Evans Glacier, Ellesmere Island, Nunavut, Canada. The microbial communities were examined using two techniques: clone libraries and dot blot hybridization of 16S rRNA genes. Two hundred twenty-seven clones containing amplified 16S rRNA genes were prepared from subglacial samples, and the gene sequences were analyzed phylogenetically. Although some phylogenetic groups, including the Betaproteobacteria, were abundant in clone libraries from both glaciers, other well-represented groups were found at only one glacier. Group-specific oligonucleotide probes were developed for two phylogenetic clusters that were of particular interest because of their abundance or inferred biochemical capabilities. These probes were used in quantitative dot blot hybridization assays with a range of samples from the two glaciers. In addition to shared phyla at both glaciers, each glacier also harbored a subglacial microbial population that correlated with the observed aqueous geochemistry. These results are consistent with the hypothesis that microbial activity is an important contributor to the solute flux from glaciers.

Subglacial Lake Whillans microbial biogeochemistry: a synthesis of current knowledge

“…The nature of any chemolithotrophic processes present is dependent on the nature of electron donor/acceptor couples available for respiration, which in turn are dependent on the chemical properties of the subglacial environment [97]. A number of factors have been implicated in controlling subglacial chemistry.…”

“…Early findings suggested that meltwater inputs controlled the amount of oxygen entering some subglacial systems and, consequently, their redox state [74]. Other studies pointed to bedrock composition as being influential in governing microbial communities by providing mineral and carbon substrates [96,97]. As the fourth most abundant element in the lithosphere, iron is likely to have a critical role in the redox chemistry of many subglacial water masses.…”

Cultivation of a novel cold-adapted nitrite oxidizing betaproteobacterium from the Siberian Arctic

“…Comparative sequence analysis of the 16S rRNA genes revealed a high level of sequence identity between the new nitrite oxidizing betaproteobacterium and clone Run-S67 (AB247475) from domestic sewage (99.0%), clone Elb 168 (AJ421928) from a biofilm of a polluted river (98.8%) (Brü mmer et al, 2003), clone BG.g12 (DQ228379) from subglacial environments (97.8%) (Skidmore et al, 2005) and clone c5LKS43 (AM086129) from sediments of the mesotrophic lake Kinneret (96.3%) (Schwarz et al, 2007). The next related taxonomically described organism is Gallionella ferruginea (93.5% similarity).…”

Ancient permafrost staphylococci carry antibiotic resistance genes

“…Microbial activity was also found in ice sediments of perennial and permanent lake ice [5,6] and in the Antarctic Sea [7,8]. Anaerobic microorganisms were isolated from glacier samples in the Arctic [9,10] and Greenland [11]. …”