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A molecular phylogenetic survey of polar sea ice microbial communities


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Brown, Mark Vincent 2000 , 'A molecular phylogenetic survey of polar sea ice microbial communities', PhD thesis, University of Tasmania.

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The structure of the Antarctic sea ice cover is highly heterogenous, with composition
in a given region depending on extremely localised physical processes. Past studies
have revealed a wide range of sea ice microbial communities (SIMCO's), associated
with a variety of ice types. Many of these assemblages are highly productive. Given
the enormous extent of the ice cover these localised but highly productive
communities constitute an important component of the regions biological processes.
To date, our knowledge of the taxonomical composition of SIMCO's extends from
culture based studies. This study employed culture independent molecular techniques
to identify biodiversity in a variety of SIMCO's. Clone libraries of 16S rRNA genes
were constructed from the total environmental DNA extracted from one Arctic and
seven Antarctic sea ice samples using universally-conserved, Archaea-specific and
Bacteria-specific 16S rDNA primers. A total of 539 recombinant clones were
obtained. Restriction fragment length polymorphism (RFLP) and sequence analysis
grouped the clones into 100 distinct phylotypes (a unique clone or group of clones
with sequence similarity >0.98) representing sympagic organisms of Bacterial and
Eukaryotic origin. Bacterial clones were affiliated with the alpha and gamma
Proteobacteria, the Cytophaga-Flavobacterium-Bacteroides Group, the
ChlamydialVerricomicrobia and the Gram positive bacteria. One clone was not
closely affiliated with any Bacterial Division. Eukaryotic clones were affiliated with
a variety of autotrophic and heterotrophic nanoplankton and included a large number
of plastid genes. A number of sequences from both groups represented putatively
novel organisms. The findings of this examination corroborate data previously
collected during culture based studies indicating bacterial biodiversity increases in
SIMCO's displaying high levels of primary productivity. Shifts in community
composition appear to be associated with alterations in the carbon budget. A
comparison of Arctic and Antarctic sea ice communities revealed several common
genera occuring at both poles.
The information gained from this study provides a focus for a number of important
future studies including in situ based analyses of SIMCO composition, cultivation of
novel organims identified by sequence anlaysis, and the examination of biogeography
of polar sea ice microbial bacteria.

Item Type: Thesis - PhD
Authors/Creators:Brown, Mark Vincent
Keywords: Microbial ecology, Extreme environments
Copyright Holders: The Author
Copyright Information:

Copyright 2000 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2000. Includes bibliographical references

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