title: Abiotic factors influence microbial diversity in permanently cold soil horizons of a maritime-associated Antarctic Dry Valley.
abstract: The McMurdo Dry Valleys collectively comprise the most extensive ice-free region in Antarctica and are considered one of the coldest arid environments on Earth. In low-altitude maritime-associated valleys, mineral soil profiles show distinct horizontal structuring, with a surface arid zone overlying a moist and biologically active zone generated by seasonally melted permafrost. In this study, long-term microenvironmental monitoring data show that temperature and soil humidity regimes vary in the soil horizons of north- and south-facing slopes within the Miers Valley, a maritime valley in the McMurdo Dry Valleys. We found that soil bacterial communities varied from the north to the south. The microbial assemblages at the surface and shallow subsurface depths displayed higher metabolic activity and diversity compared to the permafrost soil interface. Multivariate analysis indicated that K, C, Ca and moisture influenced the distribution and structure of microbial populations. Furthermore, because of the large % RH gradient between the frozen subsurface and the soil surface we propose that water transported to the surface as water vapour is available to microbial populations, either as a result of condensation processes or by direct adsorption from the vapour phase.
authors.affiliation: Institute for Microbial Biotechnology and Metagenomics, University of the Western Cape, Cape Town, South Africa.
authors.forename: Francesca
authors.initials: F
authors.lastname: Stomeo
authors.forename: Thulani P
authors.initials: TP
authors.lastname: Makhalanyane
authors.forename: Angel
authors.initials: A
authors.lastname: Valverde
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Pointing
authors.forename: Mark I
authors.initials: MI
authors.lastname: Stevens
authors.forename: Craig S
authors.initials: CS
authors.lastname: Cary
authors.forename: Marla I
authors.initials: MI
authors.lastname: Tuffin
authors.forename: Don A
authors.initials: DA
authors.lastname: Cowan
mesh_terms: D000531:Altitude; D000864:Antarctic Regions; D001419:Bacteria / Q000235:genetics / Q000254:growth & development*; D044822:Biodiversity; D004269:DNA, Bacterial / Q000235:genetics; D003890:Desiccation; D004777:Environment; D006813:Humidity; D007053:Ice; D054892:Metagenome; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D013696:Temperature; D014867:Water
chemical_list: D004269:DNA, Bacterial; D007053:Ice; D012336:RNA, Ribosomal, 16S; D012987:Soil; D014867:Water