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

• Published in: FEMS Microbiology Ecology
• Main Authors: Summers, Stephen, Whiteley, Andrew S., Kelly, Laura, Cockell, Charles S.
• Other Authors: Centre for Ecology and Hydrology, SUPA School of Physics and Astronomy Edinburgh, University of Edinburgh, School of Earth and Environment, The University of Western Australia (UWA), Interactions Arbres-Microorganismes (IAM), Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL), NERC Centre for Ecology and Hydrology, UK; Open University, UK
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: weathering; critical zone; bacteria; minerals; molecular ecology; soil microbiology; [SDV]Life Sciences [q-bio]; Arctic
• Online Access: https://hal.archives-ouvertes.fr/hal-01268513; https://doi.org/10.1111/1574-6941.12167

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=2.25x 10(7)g(-1)), whereas lichen- and moss-covered sites (LMS) had lower cell densities (LMS=1.06x10(7)cellsg(-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 -diversity than sites without, indicative of specialized communities at sites with root-forming plants.