Microbial Analyses of Ancient Ice Core Sections from Greenland and Antarctica

Abstract

Ice deposited in Greenland and Antarctica entraps viable and nonviable microbes, as well as biomolecules, that become temporal atmospheric records. Five sections (estimated to be 500, 10,500, 57,000, 105,000 and 157,000 years before present, ybp) from the GISP2D (Greenland) ice core, three sections (500, 30,000 and 70,000 ybp) from the Byrd ice core, and four sections from the Vostok 5G (Antarctica) ice core (10,500, 57,000, 105,000 and 105,000 ybp) were studied by scanning electron microscopy, cultivation and rRNA gene sequencing. Bacterial and fungal isolates were recovered from 10 of the 12 sections. The highest numbers of isolates were found in ice core sections that were deposited during times of low atmospheric CO2, low global temperatures and low levels of atmospheric dust. Two of the sections (GISP2D at 10,500 and 157,000 ybp) also were examined using metagenomic/metatranscriptomic methods. These results indicated that sequences from microbes common to arid and saline soils were deposited in the ice during a time of low temperature, low atmospheric CO2 and high dust levels. Members of Firmicutes and Cyanobacteria were the most prevalent bacteria, while Rhodotorula species were the most common eukaryotic representatives. Isolates of Bacillus, Rhodotorula, Alternaria and members of the Davidiellaceae were isolated from both Greenland and Antarctica sections of the same age, although the sequences differed between the two polar regions.

Microbial ecology of Antarctic aquatic systems

“…1), particularly of microorganisms attached to dust, pollen or water droplets 48 , provides the potential means of dispersing everything everywhere and enabling the environment to select, as per the Baas Becking hypothesis 40,[49][50][51][52][53][54] . A study of Greenland and Antarctic glacial ice cores suggests that aeolian dispersal of microorganisms is limited between the poles, with microorganisms trapped in ice having originated from geographically local regions 55 . The evidence supporting this came from ice cores from Greenland ice sheets (Greenland Ice Sheet Project 2 (GISP2)) and Antarctic ice sheets (Vostok and Byrd) that were 10,500 and 157,000 years old; these were studied using metagenomics and metatranscriptomics and were used to isolate viable cultures 55 .…”

“…A study of Greenland and Antarctic glacial ice cores suggests that aeolian dispersal of microorganisms is limited between the poles, with microorganisms trapped in ice having originated from geographically local regions 55 . The evidence supporting this came from ice cores from Greenland ice sheets (Greenland Ice Sheet Project 2 (GISP2)) and Antarctic ice sheets (Vostok and Byrd) that were 10,500 and 157,000 years old; these were studied using metagenomics and metatranscriptomics and were used to isolate viable cultures 55 . The most prevalent microbial sequences were from the phyla Firmicutes, particularly Bacillus spp., and Cyanobacteria, and although similar species were identified in Antarctic and Arctic ice cores, species composition between samples was unique 55 .…”

Abundance, viability and diversity of the indigenous microbial populations at different depths of the NEEM Greenland ice core

“…To our knowledge, this is the first study to provide a considerable amount of sequence information comparing the microbial population diversity at several depths of a 2537-m-deep polar ice core using NGS. A recent report of Knowlton et al (2013) performed a 454 metagenomic/metatransciptomic analysis of two sections of the GISP2 ice core from 1601-and 3014-m depths yielding a limited number of 33 quality sequences unique to the ice. Several other metagenomic studies of glacial ice were performed on near surface glacial ice (Simon et al 2009;Choudhari et al 2013) or on subglacial Arctic ice and accretion Vostok ice (Hamilton et al 2013;Shtarkman et al 2013).…”

“…Interestingly, the dominant group of clones from the 1729.75-m sample was related to filamentous Cyanobacteria commonly found in Antarctica and the Arctic (Quesada & Vincent 2012;Strunecky et al 2012), including in Greenland glacial ice (Knowlton et al 2013). Several cyanobacteria were also found in the 101.2-and 2051.5-m-deep NEEM ice samples.…”

Permafrost Meta-Omics and Climate Change

“…Despite oligotrophic conditions, freezing temperatures, low water availability, high salinity, and background radiation, viable microbes have been detected in permafrost that has been frozen for thousands to millions of years (Gilichinsky et al 2008;Knowlton et al 2013;Panikov 2009;Rivkina et al 1998Rivkina et al , 2000Waldrop et al 2010;Zhang et al 2013a). Although there is often less microbial biomass and diversity in permafrost than in overlying active layer soils, which are exposed to seasonal freeze-thaw cycles, several studies show that a variety of microbial phyla reside and are active in permafrost (Hultman et al 2015, Jansson & Taş 2014, Rivkina et al 2000.…”