Article

Prokaryotic Diversity of Arctic Ice Shelf Microbial Mats

Department of Natural Resource Sciences, McGill University, Montreal, Canada.
Environmental Microbiology (Impact Factor: 6.24). 04/2008; 10(4):950-66. DOI: 10.1111/j.1462-2920.2007.01516.x
Source: PubMed

ABSTRACT The prokaryotic diversity and respiratory activity of microbial mat communities on the Markham Ice Shelf and Ward Hunt Ice Shelf in the Canadian high Arctic were analysed. All heterotrophic isolates and > 95% of bacterial 16S rRNA gene clone library sequences from both ice shelves grouped within the phyla Bacteroidetes, Proteobacteria and Actinobacteria. Clone library analyses showed that the bacterial communities were diverse and varied significantly between the two ice shelves, with the Markham library having a higher estimated diversity (Chao1 = 243; 105 operational taxonomic units observed in 189 clones) than the Ward Hunt library (Chao1 = 106; 52 operational taxonomic units observed in 128 clones). Archaeal 16S rRNA gene clone libraries from both ice shelves were dominated by a single Euryarchaeota sequence, which appears to represent a novel phylotype. Analyses of community activity by radiorespiration assays detected metabolism in mat samples from both ice shelves at temperatures as low as -10 degrees C. These findings provide the first insight into the prokaryotic biodiversity of Arctic ice shelf communities and underscore the importance of these cryo-ecosystems as a rich source of microbiota that are adapted to extreme cold.

Download full-text

Full-text

Available from: Lyle G Whyte, Aug 10, 2015
0 Followers
 · 
261 Views
  • Source
    • "Martian ice wedges are high-priority targets in the search for life beyond Earth, and to expand our understanding of the habitability of such ice environments, we elected to study analog ice wedge environments from the Canadian high Arctic. The microbial communities of a variety of terrestrial cryoenvironments have been studied, such as those found in glacier ice (Skidmore et al., 2000; Miteva et al., 2004), subglacial environments (Yde et al., 2010), cryoconite holes (Sä wströ m et al., 2002), Arctic permafrost soil (Steven et al., 2009; Wilhelm et al., 2011), Antarctic Dry Valley soils and endoliths (Pointing et al., 2009), cryopegs (Gilichinsky, 2002), ice shelves (Bottos et al., 2008), high Arctic saline perennial spring environments (Perreault et al., 2007; Niederberger et al., 2009, 2010), and various other ice environments (Lacelle et al., 2011). These studies reveal complex cold-tolerant microbial communities, some of which exhibit active metabolism at in situ temperatures in ice and brine (-5°C) (Niederberger et al., 2010; Bakermans and Skidmore, 2011) and permafrost (-15°C) (Steven et al., 2008). "
  • Source
    • "degree of microbial diversity was observed in the extremely cold environments of Arctic and Antarctica [4] [5] [17] [19] [22] [37]. However, the microbial communities within the freshwater and brackish water psychrophilic lakes have been less explored compared to the marine psychrophilic microbial communities. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Microorganisms, native to the cold environments have successfully acclimatized their physiological, metabolic and biological features, exhibiting uniqueness in their enzymes, proteins, and membrane structures. These cold-active enzymes have immense biotechnological potential. The diversity of culturable bacteria in two different water lakes (the sub-glacial freshwater and the brackish) of Himalayas was analyzed using SYBR green staining and cultural methods. A total of 140 bacteria were isolated and were grouped as psychrophiles, psychrotrophs and psychrotolerant organisms, based on their optimal temperature for growth. The amplified ribosomal DNA restriction analysis using three restriction enzymes facilitated the grouping of these isolates into 96 genotypes at ≥85% polymorphism. Phylogenetic analysis using 16S rRNA gene sequences revealed that the bacterial strains from both lakes belonged to Firmicutes, Proteobacteria (α, β, and γ) or Actinobacteria. Screening of the germplasm for the activity of different cold-active hydrolases such as protease, amylase, xylanase and cellulase, revealed that about sixteen isolates were positive, and exhibiting a wide range of stability at various temperature and pH. Our results suggest that the distinctly different ecosystems of sub-glacial freshwater and brackish water lakes have diverse groups of bacteria, which can be an excellent source of extracellular hydrolases with a wide range of thermal stability. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).
    Journal of Basic Microbiology 08/2013; 53(8). DOI:10.1002/jobm.201200126 · 1.20 Impact Factor
  • Source
    • "The phototrophic communities in these mats rely on internal nutrient recycling and scavenging systems to cope with the low allochthonous input of nutrients that is typical of ultra-oligotrophic freshwater ecosystems in the polar desert environment (Varin et al., 2010). The mat consortia contain diverse Bacteria (Bottos et al., 2008) as well as Archaea and viruses (Varin et al., 2010). Microscopic studies have long indicated that eukaryotes including metazoa (Murray, 1910) also occur in polar mats, but little is known about the diversity of microbial eukaryotes that may be present and their distribution across habitats, regions or continents. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Cyanobacterial mats are commonly found in freshwater ecosystems throughout the polar regions. Most mats are multilayered three-dimensional structures with the filamentous cyanobacteria embedded in a gel-like matrix. Although early descriptions mentioned the presence of larger organisms including metazoans living in the mats, there have been few studies specifically focused on the microbial eukaryotes, which are often small cells with few morphological features suitable for identification by microscopy. Here, we applied 18S rRNA gene clone library analysis to identify eukaryotes in cyanobacterial mat communities from both the Antarctic and the extreme High Arctic. We identified 39 ribotypes at the level of 99% sequence similarity. These consisted of taxa within algal and other protist groups including Chlorophyceae, Prasinophyceae, Ulvophyceae, Trebouxiophyceae, Bacillariophyceae, Chrysophyceae, Ciliophora, and Cercozoa. Fungi were also recovered, as were 21 metazoan ribotypes. The eukaryotic taxa appeared habitat-specific with little overlap between lake, pond, and ice shelf communities. Some ribotypes were common to both Arctic and Antarctic mats, suggesting global dispersal of these taxa and similarity in the environmental filters acting on protist communities. Many of these eukaryotic taxa likely benefit from protected, nutrient-rich microhabitats within the cyanobacterial mat environment.
    FEMS Microbiology Ecology 05/2012; 82(2):416-28. DOI:10.1111/j.1574-6941.2012.01418.x · 3.88 Impact Factor
Show more