Prokaryotic Abundance and Activity in Permafrost of the Northern Victoria Land and Upper Victoria Valley (Antarctica)
- 293 Downloads
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.
KeywordsPermafrost Microbial community Microbial activity Physiological profiles Antarctica
This work was supported by grants from the National Antarctic Research Program (PNRA), Italian Ministry of Education and Research (Research Project PNRA 2013/AZ1.05) and from the National Council of Research (CNR) in the frame of the Short Term Mobility 2015 (STM, AMMCNT-CNR N. 0058167). Our thanks to all the staff at “Mario Zucchelli” Station, for the logistic help and support, which made possible the expedition. We want to thank Dr. Fabio Baio and Dr. Andrea Strini for their role in the drilling and sampling procedures, Dr. Giulia Maricchiolo and Mr. Michele Furnari (CNR-IAMC) for laboratory availability and for technical instrument helps, respectively, as well as Dr. Daniela Zampino (CNR-IPCB) and Dr. Fabrizio Ioppolo for their friendly technical support.
- 22.Guglielmin M, Biasini A, Smiraglia C (1997) The contribution of geoelectrical investigations in the analysis of periglacial and glacial landforms in ice free areas of the Northern Foothills (Northern Victoria Land, Antarctica). Geographiska Annaler: Series A, Physical Geography 79:17–24CrossRefGoogle Scholar
- 26.Hoppe HG (1993) Use of fluorogenic model substrates for extracellular enzyme activity (EEA) measurement of bacteria. In: Kemp PF, Sherr BF, Sherr EB, Cole JJ (eds) Handbook of methods in aquatic microbial ecology. FL Lewis Publisher, Boca Raton, pp. 423–432Google Scholar
- 37.Mulyukin AL, Demkina EV, Manucharova NA, Akimov VN, Andersen D, McKay C, Gal’chenko VF (2014) The prokaryotic community of subglacial bottom sediments of Antarctic Lake Untersee: detection by cultural and direct microscopic techniques. Mikrobiologiya 83(2):215–224Google Scholar
- 38.Niederberger TD, Sohm JA, Gunderson TE, et al (2015) Microbial community composition of transiently wetted Antarctic Dry Valley soils. Front. Microbiol. 6:1–12Google Scholar
- 39.Orombelli G, Baroni C, Denton GH (1991) Late Cenozoic glacial history of the Terra Nova Bay region, Northern Victoria Land, Antarctica. Geogr. Fis. Din. Quat. 13(2):139–163Google Scholar
- 54.Waldrop MP, Wickland KP, White III R, et al (2010) Molecular investigations into a globally important carbon pool: permafrost-protected carbon in Alaskan soils. Glob. Chang. Biol. 16:2543–2554Google Scholar