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Evidence of adaptation, niche separation and microevolution within the genus Polaromonas on Arctic and Antarctic glacial surfaces.

https://arctichealth.org/en/permalink/ahliterature271909
Source
Extremophiles. 2016 Apr 20;
Publication Type
Article
Date
Apr-20-2016
Author
Jan Gawor
Jakub Grzesiak
Joanna Sasin-Kurowska
Piotr Borsuk
Robert Gromadka
Dorota Górniak
Aleksander Swiatecki
Tamara Aleksandrzak-Piekarczyk
Marek K Zdanowski
Source
Extremophiles. 2016 Apr 20;
Date
Apr-20-2016
Language
English
Publication Type
Article
Abstract
Polaromonas is one of the most abundant genera found on glacier surfaces, yet its ecology remains poorly described. Investigations made to date point towards a uniform distribution of Polaromonas phylotypes across the globe. We compared 43 Polaromonas isolates obtained from surfaces of Arctic and Antarctic glaciers to address this issue. 16S rRNA gene sequences, intergenic transcribed spacers (ITS) and metabolic fingerprinting showed great differences between hemispheres but also between neighboring glaciers. Phylogenetic distance between Arctic and Antarctic isolates indicated separate species. The Arctic group clustered similarly, when constructing dendrograms based on 16S rRNA gene and ITS sequences, as well as metabolic traits. The Antarctic strains, although almost identical considering 16S rRNA genes, diverged into 2 groups based on the ITS sequences and metabolic traits, suggesting recent niche separation. Certain phenotypic traits pointed towards cell adaptation to specific conditions on a particular glacier, like varying pH levels. Collected data suggest, that seeding of glacial surfaces with Polaromonas cells transported by various means, is of greater efficiency on local than global scales. Selection mechanisms present of glacial surfaces reduce the deposited Polaromonas diversity, causing subsequent adaptation to prevailing environmental conditions. Furthermore, interactions with other supraglacial microbiota, like algae cells may drive postselectional niche separation and microevolution within the Polaromonas genus.
PubMed ID
27097637 View in PubMed
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Identification of miniature plasmids in psychrophilic Arctic bacteria of the genus Variovorax.

https://arctichealth.org/en/permalink/ahliterature270585
Source
FEMS Microbiol Ecol. 2016 Apr;92(4)
Publication Type
Article
Date
Apr-2016
Author
Anna Ciok
Lukasz Dziewit
Jakub Grzesiak
Karol Budzik
Dorota Gorniak
Marek K Zdanowski
Dariusz Bartosik
Source
FEMS Microbiol Ecol. 2016 Apr;92(4)
Date
Apr-2016
Language
English
Publication Type
Article
Abstract
The Svalbard archipelago (Spitsbergen Island) is the northernmost landmass in the European Arctic and has a variety of small- and medium-sized glaciers. The plasmidome of eleven psychrophilic strains of Variovorax spp. isolated from the ice surface of Hans and Werenskiold Glaciers of Spitsbergen Island, was defined. This analysis revealed the presence of six plasmids whose nucleotide sequences have been determined. Four of them, exhibiting high reciprocal sequence similarity, possess unique structures, since their genomes lack any recognized genes. These miniature replicons, not exceeding 1 kb in size, include pHW69V1 (746 bp), which is the smallest autonomous replicon so far identified in free-living bacteria. The miniature plasmids share no similarity with known sequences present in the databases. In silico and experimental analyses identified conserved DNA regions essential for the initiation of replication of these replicons.
PubMed ID
26917781 View in PubMed
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Microbial community development on the surface of Hans and Werenskiold Glaciers (Svalbard, Arctic): a comparison.

https://arctichealth.org/en/permalink/ahliterature263930
Source
Extremophiles. 2015 Jun 24;
Publication Type
Article
Date
Jun-24-2015
Author
Jakub Grzesiak
Dorota Górniak
Aleksander Swiatecki
Tamara Aleksandrzak-Piekarczyk
Katarzyna Szatraj
Marek K Zdanowski
Source
Extremophiles. 2015 Jun 24;
Date
Jun-24-2015
Language
English
Publication Type
Article
Abstract
Surface ice and cryoconite holes of two types of polythermal Svalbard Glaciers (Hans Glacier-grounded tidewater glacier and Werenskiold Glacier-land-based valley glacier) were investigated in terms of chemical composition, microbial abundance and diversity. Gathered data served to describe supraglacial habitats and to compare microbe-environment interactions on those different type glaciers. Hans Glacier samples displayed elevated nutrient levels (DOC, nitrogen and seston) compared to Werenskiold Glacier. Adjacent tundra formations, bird nesting sites and marine aerosol were candidates for allochtonic enrichment sources. Microbial numbers were comparable on both glaciers, with surface ice containing cells in the range of 10(4) mL(-1) and cryoconite sediment 10(8) g(-1) dry weight. Denaturating gradient gel electrophoresis band-based clustering revealed differences between glaciers in terms of dominant bacterial taxa structure. Microbial community on Werenskiold Glacier benefited from the snow-released substances. On Hans Glacier, this effect was not as pronounced, affecting mainly the photoautotrophs. Over-fertilization of Hans Glacier surface was proposed as the major factor, desensitizing the microbial community to the snow melt event. Nitrogen emerged as a limiting factor in surface ice habitats, especially to Eukaryotic algae.
PubMed ID
26104673 View in PubMed
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