16S rDNA diversity of cultured and uncultured prokaryotes of a mat sample from Lake Fryxell, McMurdo Dry Valleys, Antarctica

Abstract

The prokaryotic diversity of aerobic and anaerobic bacterial isolates and of bacterial and archaeal 16S rDNA clones was determined for a microbial mat sample from the moated region of Lake Fryxell, McMurdo Dry Valleys, Antarctica. Among the anaerobic bacteria, members of Clostridium estertheticum and some other psychrotolerant strains dominated whereas methanogens and other Archaea were lacking. Isolates highly related to Flavobacterium hibernum, Janthiniobacterium lividum, and Arthrobacter flavus were among the aerobic bacteria most frequently isolated. Assessment of more than 350 partial 16S rDNA clone sequences of libraries generated by Bacteria- and Archaea-specific PCR primers revealed a rich spectrum of bacterial diversity but only two different archaeal clone sequences. Among the Bacteria, representative sequences belonged to the class Proteobacteria, order Verrucomicrobiales, class Actinobacteria, Clostridium/Bacillus subphylum of Gram-positives, and the Cytophaga-Flavobacterium-Bacteroides phylum. The clones formed about 70 higher taxonomy groups (<98% sequence similarity) and 133 potential species, i.e., groups of clones sharing greater than 98% similarity. Only rarely were clone sequences found to be highly related to Lake Fryxell isolates and to strains of described species. Subsequent analysis of ten sequencing batches of 36 individual clones indicated that the diversity might be still higher than had been assessed.

High 16S rDNA bacterial diversity in glacial meltwater lake sediment, Bratina Island, Antarctica

“…Our results show that the prokaryotic diversity is comparable to, if not higher than, that shown in other studies of Antarctic meltwater lake sediments (Bowman et al 2000), microbial mats in East Antarctic lakes (Brambilla et al 2001), and the Arctic Ocean (Raven-schlag et al 1999), each of which report a high level of complexity in the prokaryotic community structure. The linearity of the rarefaction curve (Fig.…”

“…Putative strains are related to species detected either in cold marine or lake waters and sediment or in bioremediation processes, with several heterotrophs involved in the cycling of CO 2 and inorganic nutrients and decomposition. Some of the more metabolically 'specialized' bacteria, such as the Fe (III)-reducing Pelobacter, have also been detected in microbial mats in Lake Fryxell, Antarctic Dry Valleys (Brambilla et al 2001). …”

Microbiology of Eutrophic (Ornithogenic and Hydrocarbon-Contaminated) Soil

“…The absence of hydrological features (ponds and lakes) in the Beacon Valley compared to Miers Valley was considered an important factor in explaining the differences in cyanobacterial compositions between the two valleys (Wood et al 2008). Heterotrophic bacteria in microbial mats, which include representatives of the phyla Actinobacteria, Proteobacteria, Bacteroidetes, Firmicutes, and Deinococcus-Thermus (Brambilla et al 2001;Van Trappen et al 2002;Rojas et al 2009;Peeters et al 2011), may be similarly redistributed by aeolian processes in Antarctic ecosystems. Indeed, proximity to hydrological features was found to be more important than soil moisture for describing variation in both bacterial and cyanobacterial community structures in Miers Valley soils (Niederberger et al 2012).…”

Bacillus cecembensis sp. nov., isolated from the Pindari glacier of the Indian Himalayas

“…The ubiquitous distribution of Bacillus species in nature is due to the resistance of their endospores to chemical and physical agents. Species of Bacillus have been shown to be resistant to radiation (Shivaji et al, 2006;Venkateswaran et al, 2003), extremely low temperatures (Brambilla et al, 2001;Logan et al, 2000;Rüger et al, 2000;Nelson & Parkinson, 1978;Abd El-Rahman et al, 2002;Lechner et al, 1998), high temperatures (Baker et al, 2001;Caccamo et al, 2000;Combet-Blanc et al, 1995), salinity Lee et al, 2006;Gugliandolo et al, 2003), alkalinity (Nogi et al, 2005;Vargas et al, 2005;Yumoto et al, 1998), acidity (Albert et al, 2005) and high pressure (Bae et al, 2005). Although Bacillus species have been isolated from a wide range of habitats, only one Bacillus species with a validly published name, Bacillus lehensis (Ghosh et al, 2007), has been isolated from the Himalayan region.…”