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Global Diversity of Desert Hypolithic Cyanobacteria.

https://arctichealth.org/en/permalink/ahliterature282887
Source
Front Microbiol. 2017;8:867
Publication Type
Article
Date
2017
Author
Donnabella C Lacap-Bugler
Kevin K Lee
Stephen Archer
Len N Gillman
Maggie C Y Lau
Sebastian Leuzinger
Charles K Lee
Teruya Maki
Christopher P McKay
John K Perrott
Asunción de Los Rios-Murillo
Kimberley A Warren-Rhodes
David W Hopkins
Stephen B Pointing
Source
Front Microbiol. 2017;8:867
Date
2017
Language
English
Publication Type
Article
Abstract
Global patterns in diversity were estimated for cyanobacteria-dominated hypolithic communities that colonize ventral surfaces of quartz stones and are common in desert environments. A total of 64 hypolithic communities were recovered from deserts on every continent plus a tropical moisture sufficient location. Community diversity was estimated using a combined t-RFLP fingerprinting and high throughput sequencing approach. The t-RFLP analysis revealed desert communities were different from the single non-desert location. A striking pattern also emerged where Antarctic desert communities were clearly distinct from all other deserts. Some overlap in community similarity occurred for hot, cold and tundra deserts. A further observation was that the producer-consumer ratio displayed a significant negative correlation with growing season, such that shorter growing seasons supported communities with greater abundance of producers, and this pattern was independent of macroclimate. High-throughput sequencing of 16S rRNA and nifH genes from four representative samples validated the t-RFLP study and revealed patterns of taxonomic and putative diazotrophic diversity for desert communities from the Taklimakan Desert, Tibetan Plateau, Canadian Arctic and Antarctic. All communities were dominated by cyanobacteria and among these 21 taxa were potentially endemic to any given desert location. Some others occurred in all but the most extreme hot and polar deserts suggesting they were relatively less well adapted to environmental stress. The t-RFLP and sequencing data revealed the two most abundant cyanobacterial taxa were Phormidium in Antarctic and Tibetan deserts and Chroococcidiopsis in hot and cold deserts. The Arctic tundra displayed a more heterogenous cyanobacterial assemblage and this was attributed to the maritime-influenced sampling location. The most abundant heterotrophic taxa were ubiquitous among samples and belonged to the Acidobacteria, Actinobacteria, Bacteroidetes, and Proteobacteria. Sequencing using nitrogenase gene-specific primers revealed all putative diazotrophs were Proteobacteria of the orders Burkholderiales, Rhizobiales, and Rhodospirillales. We envisage cyanobacterial carbon input to the system is accompanied by nitrogen fixation largely from non-cyanobacterial taxa. Overall the results indicate desert hypoliths worldwide are dominated by cyanobacteria and that growing season is a useful predictor of their abundance. Differences in cyanobacterial taxa encountered may reflect their adaptation to different moisture availability regimes in polar and non-polar deserts.
PubMed ID
28559886 View in PubMed
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Nearing the cold-arid limits of microbial life in permafrost of an upper dry valley, Antarctica.

https://arctichealth.org/en/permalink/ahliterature273775
Source
ISME J. 2016 Jul;10(7):1613-24
Publication Type
Article
Date
Jul-2016
Author
Jacqueline Goordial
Alfonso Davila
Denis Lacelle
Wayne Pollard
Margarita M Marinova
Charles W Greer
Jocelyn DiRuggiero
Christopher P McKay
Lyle G Whyte
Source
ISME J. 2016 Jul;10(7):1613-24
Date
Jul-2016
Language
English
Publication Type
Article
Abstract
Some of the coldest and driest permafrost soils on Earth are located in the high-elevation McMurdo Dry Valleys (MDVs) of Antarctica, but little is known about the permafrost microbial communities other than that microorganisms are present in these valleys. Here, we describe the microbiology and habitable conditions of highly unique dry and ice-cemented permafrost in University Valley, one of the coldest and driest regions in the MDVs (1700?m above sea level; mean temperature -23?°C; no degree days above freezing), where the ice in permafrost originates from vapour deposition rather than liquid water. We found that culturable and total microbial biomass in University Valley was extremely low, and microbial activity under ambient conditions was undetectable. Our results contrast with reports from the lower-elevation Dry Valleys and Arctic permafrost soils where active microbial populations are found, suggesting that the combination of severe cold, aridity, oligotrophy of University Valley permafrost soils severely limit microbial activity and survival.
PubMed ID
27323892 View in PubMed
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