Microbial community composition of lake sediment in the High Arctic
Permanent URL:
http://hdl.handle.net/2047/D20248636
Godoy-Carter, Veronica (Committee member)
Lewis, Kim (Committee member)
Chai, Yunrong (Committee member)
Nelson, Karen E. (Committee member)
1. Utilize cultivation-independent molecular approaches to define microbial community structure and identify potentially active organisms
2. Utilize culture-dependent approaches to create a comprehensive culture collection
3. Analyze and synthesize the data obtained from Aims 1 and 2 and assess the biological relevance of cultured organisms
The community appeared relatively rich and stable over time based upon a 16S rRNA gene survey. However, analysis of the expressed 16S rRNA genes indicated that activity of operational taxonomic units (OTUs) within the sediment community was dynamic, even across very small distances. Additionally, the most active members were not represented in any database to date.
Despite increasing advancements in microbial cultivation, our results emphasize the need to develop new tools and techniques. A total of 1173 strains were cultivated, but only a small fraction was detected as active (<7%), or even present in the community (<12%) based on 16S gene surveys. We conclude that the variation in OTU activity between replicate samples, and the low abundance and activity of OTUs cultured, are a result of microheterogeneity in spatial distribution within microbial communities. Thus, samples taken even millimeters apart were actually from potentially different communities. The results of this dissertation highlight the increasing need to study microbial communities on a scale relevant to microbial life.
community
cultivation
extreme
microbial
uncultivated
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