Journal Article

Land coverage influences the bacterial community composition in the critical zone of a sub-Arctic basaltic environment

Stephen Summers, Andrew S. Whiteley, Laura C. Kelly and Charles S. Cockell

in FEMS Microbiology Ecology

Volume 86, issue 3, pages 381-393
Published in print December 2013 |
Published online November 2013 | e-ISSN: 1574-6941 | DOI:

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Silicate weathering improves soils by releasing bioessential nutrients from the bedrock to the soil ecosystem. However, whether bacteria are capable of inhabiting subsurface critical zones (zone of active rock weathering), and their role therein, are unknown. Next-generation sequencing and community fingerprinting permitted us to characterize communities from an Icelandic critical zone environment. Communities were compared with respect to physico-chemical properties of the environment to determine the factors influencing bacterial diversity. We showed that land coverage influenced critical zone communities. Analysis of tree-covered site (TCS) soils exhibited high cell densities (TCS = 2.25 × 107 g−1), whereas lichen- and moss-covered sites (LMS) had lower cell densities (LMS = 1.06 × 107 cells g−1), thought to be a result of the organic carbon produced by the trees. Differences in the bacterial community were observed from the abundance of 16S rRNA gene sequences affiliated with Acidobacteria and Proteobacteria, with TCS possessing higher abundances of Proteobacteria [no of sequences: LMS = 1526 (±497); TCS = 2214 (±531)], specifically Alpha- and Betaproteobacteria, and lower Acidobacteria numbers [no of sequences: LMS = 1244 (±338); TCS = 598 (±140)]. Diversity indices and 16S rRNA gene rarefaction showed that communities from TCS soils had lower α-diversity than sites without, indicative of specialized communities at sites with root-forming plants.

Keywords: critical zone; weathering; bacteria; minerals; Soil Microbiology; Molecular Ecology

Journal Article.  6972 words.  Illustrated.

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