RESEARCH ARTICLE International Microbiology 19(3):161-173 (2016) doi:10.2436/20.1501.01.274. ISSN (print): 1139-6709. e-ISSN: 1618-1095 www.im.microbios.org Functional ecology of soil microbial communities along a glacier forefield in Tierra del Fuego (Chile) Miguel A. Fernández-Martínez, 1 Stephen B. Pointing, 2 Sergio Pérez-Ortega, 1,3 María Arróniz-Crespo, 4,5 T. G. Allan Green, 5 Ricardo Rozzi, 6 Leopoldo G. Sancho, 5 Asunción de los Ríos 1* 1 Department of Biochemistry and Microbial Ecology, Museo Nacional de Ciencias Naturales, CSIC. Madrid, Spain. 2 Institute for Applied Ecology, Auckland University of Technology, Auckland, New Zealand. 3 Real Jardín Botánico, CSIC, Madrid, Spain. 4 Department of Chemistry and Tecnology of Food, Universidad Politécnica de Madrid, Madrid, Spain. 5 Department of Plant Biology II. Universidad Complutense de Madrid, Madrid, Spain. 6 Institute of Ecology and Biodiversity, University of Magallanes, Puerto Williams, Chile Received 25 August 2016 · Accepted 25 September 2016 Summary. A previously established chronosequence from Pia Glacier forefeld in Tierra del Fuego (Chile) containing soils of diferent ages (from bare soils to forest ones) is analyzed. We used this chronosequence as framework to postulate that microbial successional development would be accompanied by changes in functionality. To test this, the GeoChip functional microarray was used to identify diversity of genes involved in microbial carbon and nitrogen metabolism, as well as other genes related to microbial stress response and biotic interactions. Changes in putative functionality generally refected succession-related taxonomic compo- sition of soil microbiota. Major shifts in carbon fxation and catabolism were observed, as well as major changes in nitrogen metabolism. At initial microbial dominated succession stages, microorganisms could be mainly involved in pathways that help to increase nutrient availability, while more complex microbial transformations such as denitrifcation and methanogenesis, and later degradation of complex organic substrates, could be more prevalent at vegetated successional states. Shifts in virus populations broadly refected changes in microbial diversity. Conversely, stress response pathways appeared relatively well conserved for communities along the entire chronosequence. We conclude that nutrient utilization is likely the major driver of microbial succession in these soils. [Int Microbiol 19(3):161-173 (2016)] Keywords: Functional genes · antibiotic resistance · GeoChip microarray · primary succession · chronosequence * Corresponding author: A. de los Ríos E-mail: arios@mncn.csic.es Introduction Microorganisms play a fundamental role in the initial coloni- zation of exposed soils after glacial retreat [9,29,31,43,65]. Pioneer microorganisms are responsible for most biological transformations and drive the development of stable and la- bile pools of nutrients [5,33] that facilitate further microbial colonization, and, subsequently establishment of lichens, bryophytes and vascular plants [9,13,51]. Numerous studies have investigated the changes in microbial community com- position along chronosequences in glacier forelands [9,39,59, 65]. However, the associated changes in functional commu- nity structure and their role in the succession are still poorly understood. Soil microbial communities underpin carbon (C) and ni- trogen (N) transformation processes (e.g., photosynthesis, N 2 fxation, substrate decomposition, nutrient mineralization), Supplementary information (SI) [http://hdl.handle.net/10261/147168] contains additional Figures and Tables.