title: Prokaryotic Abundance and Activity in Permafrost of the Northern Victoria Land and Upper Victoria Valley (Antarctica).
abstract: Victoria Land permafrost harbours a potentially large pool of cold-affected microorganisms whose metabolic potential still remains underestimated. Three cores (BC-1, BC-2 and BC-3) drilled at different depths in Boulder Clay (Northern Victoria Land) and one sample (DY) collected from a core in the Dry Valleys (Upper Victoria Valley) were analysed to assess the prokaryotic abundance, viability, physiological profiles and potential metabolic rates. The cores drilled at Boulder Clay were a template of different ecological conditions (different temperature regime, ice content, exchanges with atmosphere and with liquid water) in the same small basin while the Dry Valleys site was very similar to BC-2 conditions but with a complete different geological history and ground ice type. Image analysis was adopted to determine cell abundance, size and shape as well as to quantify the potential viable and respiring cells by live/dead and 5-cyano-2,3-ditolyl-tetrazolium chloride staining, respectively. Subpopulation recognition by apparent nucleic acid contents was obtained by flow cytometry. Moreover, the physiological profiles at community level by Biolog-Ecoplate™ as well as the ectoenzymatic potential rates on proteinaceous (leucine-aminopeptidase) and glucidic (ß-glucosidase) organic matter and on organic phosphates (alkaline-phosphatase) by fluorogenic substrates were tested. The adopted methodological approach gave useful information regarding viability and metabolic performances of microbial community in permafrost. The occurrence of a multifaceted prokaryotic community in the Victoria Land permafrost and a large number of potentially viable and respiring cells (in the order of 104-105) were recognised. Subpopulations with a different apparent DNA content within the different samples were observed. The physiological profiles stressed various potential metabolic pathways among the samples and intense utilisation rates of polymeric carbon compounds and carbohydrates, mainly in deep samples. The measured enzymatic activity rates suggested the potential capability of the microbial community to decompose proteins and polysaccharides. The microbial community seems to be appropriate to contribute to biogeochemical cycling in this extreme environment.
authors.affiliation: National Council of Research (IAMC-CNR), Institute for Coastal Marine Environment, Spianata San Raineri 86, 98122, Messina, Italy. rosabruna.laferla@iamc.cnr.it.
authors.forename: Rosabruna
authors.identifier: 0000-0003-1029-7349
authors.initials: R
authors.lastname: La Ferla
authors.affiliation: National Council of Research (IAMC-CNR), Institute for Coastal Marine Environment, Spianata San Raineri 86, 98122, Messina, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Azzaro
authors.affiliation: Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166, Messina, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Michaud
authors.affiliation: National Council of Research (IAMC-CNR), Institute for Coastal Marine Environment, Spianata San Raineri 86, 98122, Messina, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Caruso
authors.affiliation: National Council of Research (IAMC-CNR), Institute for Coastal Marine Environment, Spianata San Raineri 86, 98122, Messina, Italy.|Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166, Messina, Italy.
authors.forename: Angelina
authors.initials: A
authors.lastname: Lo Giudice
authors.affiliation: Institute of Biology, Federal University of Rio de Janeiro, Prédio do CCS, Cidade Universitária do Fundao, Rio de Janeiro, Brazil.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Paranhos
authors.affiliation: Institute of Biology, Federal University of Rio de Janeiro, Prédio do CCS, Cidade Universitária do Fundao, Rio de Janeiro, Brazil.
authors.forename: Anderson S
authors.initials: AS
authors.lastname: Cabral
authors.affiliation: Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166, Messina, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Conte
authors.affiliation: National Council of Research (IAMC-CNR), Institute for Coastal Marine Environment, Spianata San Raineri 86, 98122, Messina, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cosenza
authors.affiliation: National Council of Research (IAMC-CNR), Institute for Coastal Marine Environment, Spianata San Raineri 86, 98122, Messina, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Maimone
authors.affiliation: Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166, Messina, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Papale
authors.affiliation: National Council of Research (IAMC-CNR), Institute for Coastal Marine Environment, Spianata San Raineri 86, 98122, Messina, Italy.
authors.forename: Alessandro Ciro
authors.initials: AC
authors.lastname: Rappazzo
authors.affiliation: Department of Theoretical and Applied Sciences, University of Insubria, Via J.H. Dunant 3, Varese, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Guglielmin
mesh_terms: D000864:Antarctic Regions; D003080:Cold Temperature; D004798:Enzymes / Q000032:analysis; D065946:Permafrost / Q000382:microbiology*; D012988:Soil Microbiology; D014867:Water
chemical_list: D004798:Enzymes; D014867:Water
keywords: Antarctica; Microbial activity; Microbial community; Permafrost; Physiological profiles