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Abstracts of the 3rd Annual Argonne Soil Metagenomics Workshop, Chicago, IL, Oct. 5-7, 2011.
Aspects of Adaptation by Same Bacterial Genus to Diverse Environments
Authors
S. Geetha Saarunya1, Tatiana Vishnivetskaya1, Karuna Chourey2, Alice C. Layton1, and Susan M. Pfiffner1
1
Affiliation
Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN
2
Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN
INTRODUCTION: Microorganisms are considered to be the oldest forms of life and are known to occupy all the
major environments including air, water, and soil. Extreme environmental conditions such as the hot or cold
temperatures may affect the genomic evolution of these organisms. The genetic alterations which occur within a
taxonomic group would enlarge the concept of bacterial species and their adaptation to diverse environments. One
example is the genus Exiguobacterium, which thrives from subfreezing to thermal environs.
HYPOTHESIS: The ability of Exiguobacterium genus members to survive and proliferate in both low and high
thermal regimes could be attributed to the core genome containing essential cold and heat stress responsive genes
which have evolved through genomic rearrangements and or horizontal gene transfer.
RESULTS: The sequences of Exiguobacterium sibiricum 255-15 (GenBank no. CP001022) and Exiguobacterium
sp. AT1b (GenBank no CP001615) were downloaded from NCBI. These bacteria belong to different species, as
evidenced from the average nucleotide identity between these strains. It was calculated using the Jspecies software
(http://www.imedea.uib.es/jspecies/) and was found to be 69.2%; which is below the 94% cut off expected for in
silico species delineation. Out of 81 stress-responsive genes studied, nine genes were common in both genomes (1).
MAUVE multiple genome alignment software was used to identify regions of genomic rearrangements (2).
Probabilistic analysis of horizontal gene transfer was performed on the nine genes based on the criteria specified by
Koonin et al. (3).
CONCLUSIONS: The results from this study can be further used to explore the adaptation mechanisms of a
microorganism for extreme environments.
REFERENCES
1.
Vishnivetskaya TA, Kathariou S, Tiedje JM. 2009. The Exiguobacterium genus: biodiversity and
biogeography. Extremophiles 13(3): 541-555
2.
Aaron C.E. Darling, Bob Mau, Frederick R. Blatter, and Nicole T. Perna. 2004. Mauve: multiple alignment
of conserved genomic sequence with rearrangements. Genome Research. 14(7):1394-1403.
3.
Koonin EV, Makarova KS, Aravind L: Horizontal gene transfer in prokaryotes: quantification and
classification. Annu Rev Microbiol 2001, 55:709-742