Bacterial diversity in rhizosphere soil from Antarctic vascular plants of Admiralty Bay, maritime Antarctica

Abstract

The Antarctic is a pristine environment that contributes to the maintenance of the global climate equilibrium. The harsh conditions of this habitat are fundamental to selecting those organisms able to survive in such an extreme habitat and able to support the relatively simple ecosystems. The DNA of the microbial community associated with the rhizospheres of Deschampsia antarctica Desv (Poaceae) and Colobanthus quitensis (Kunth) BartI (Caryophyllaceae), the only two native vascular plants that are found in Antarctic ecosystems, was evaluated using a 16S rRNA multiplex 454 pyrosequencing approach. This analysis revealed similar patterns of bacterial diversity between the two plant species from different locations, arguing against the hypothesis that there would be differences between the rhizosphere communities of different plants. Furthermore, the phylum distribution presented a peculiar pattern, with a bacterial community structure different from those reported of many other soils. Firmicutes was the most abundant phylum in almost all the analyzed samples, and there were high levels of anaerobic representatives. Also, some phyla that are dominant in most temperate and tropical soils, such as Acidobacteria, were rarely found in the analyzed samples. Analyzing all the sample libraries together, the predominant genera found were Bifidobacterium (phylum Actinobacteria), Arcobacter (phylum Proteobacteria) and Faecalibacterium (phylum Firmicutes). To the best of our knowledge, this is the first major bacterial sequencing effort of this kind of soil, and it revealed more than expected diversity within these rhizospheres of both maritime Antarctica vascular plants in Admiralty Bay, King George Island, which is part of the South Shetlands archipelago.

Molecular characterization of microbial communities in the rhizosphere soils and roots of diseased and healthy Panax notoginseng

“…3), which was similar to several previous studies (Lauber Teixeira et al 2010), the data obtained was valid for detecting the differences in microbial community structure between healthy and diseased plants at OTU ( Fig. 3; Table 5) and phylum levels (Table 6).…”

Microbiology of Eutrophic (Ornithogenic and Hydrocarbon-Contaminated) Soil

“…Rhizosphere soils were dominated by representatives of the phyla Firmicutes, Actinobacteria, and Proteobacteria. The high representation of Firmicutes in rhizosphere soils is notable as this group is not found to make up a substantial proportion of the bacterial communities in unvegetated soils of the region (Yergeau et al 2007b;Teixeira et al 2010). A high proportion of Firmicutes was found to group to the Clostridia, suggesting bacterial community structure may be influenced by anaerobic conditions of the rhizosphere.…”

“…On Livingston Island, Bacteroidetes were found to be enriched in moss covered soils compared with the surrounding unvegetated soils, which may be related directly to the plant cover or to the reduced soil pH (Ganzert et al 2011). On King George Island, rhizosphere soils of the flowering plants Deschampsia antarctica and Colobanthus quitensis have been found to support similar bacterial communities, and these communities are very different to those reported in unvegetated soils in the region (Teixeira et al 2010). Rhizosphere soils were dominated by representatives of the phyla Firmicutes, Actinobacteria, and Proteobacteria.…”

Reproducibility and quantitation of amplicon sequencing-based detection

“…At present, the 454 pyrosequencing technology has been widely used to reveal microbial diversity and ecology in different natural environments, such as the deep sea (Sogin et al, 2006;Huber et al, 2007), extreme hydrogeological conditions (Edwards et al, 2006) and soil (Leininger et al, 2006;Roesch et al, 2007). In addition, multiplexed high-throughput pyrosequencing of individual genes (for example, 16S rRNA) by tagging or bar coding with short nucleotides (also called pyrotag sequencing ) Parameswaran et al, 2007;Roesch et al, 2007;Hamady et al, 2008) has been developed to process many samples simultaneously and has been widely used in microbial community studies (Youssef et al, 2009;Cheung et al, 2010;Chun et al, 2010;He et al, 2010a, b;Koopman et al, 2010;Schutte et al, 2010;Teixeira et al, 2010;Uroz et al, 2010). A similar strategy has also been used for sequencing functional genes (Iwai et al, 2010).…”