The Exiguobacterium genus: biodiversity and biogeography |
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Authors: | Tatiana A Vishnivetskaya Sophia Kathariou James M Tiedje |
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Institution: | (1) North Carolina State University, Raleigh, NC 27695, USA;(2) Center for Microbial Ecology, Michigan State University, East Lansing, MI 48823, USA;(3) Present address: Microbial Ecology and Physiology Group, Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Bldg. 1505, Rm. 392, MS-6038, Oak Ridge, TN 37831-6038, USA |
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Abstract: | Bacteria of the genus Exiguobacterium are low G + C, Gram-positive facultative anaerobes that have been repeatedly isolated from ancient Siberian permafrost. In
addition, Exiguobacterium spp. have been isolated from markedly diverse sources, including Greenland glacial ice, hot springs at Yellowstone National
Park, the rhizosphere of plants, and the environment of food processing plants. Strains of this hereto little known bacterium
that have been retrieved from such different (and often extreme) environments are worthy of attention as they are likely to
be specifically adapted to such environments and to carry variations in the genome which may correspond to psychrophilic and
thermophilic adaptations. However, comparative genomic investigations of Exiguobacterium spp. from different sources have been limited. In this study, we employed different molecular approaches for the comparative
analysis of 24 isolates from markedly diverse environments including ancient Siberian permafrost and hot springs at Yellowstone
National Park. Pulsed-field gel electrophoresis (PFGE) with I-CeuI (an intron-encoded endonuclease), AscI and NotI were optimized for the determination of genomic fingerprints of nuclease-producing isolates. The application of a DNA macroarray
for 82 putative stress-response genes yielded strain-specific hybridization profiles. Cluster analyses of 16S rRNA gene sequence
data, PFGE I-CeuI restriction patterns and hybridization profiles suggested that Exiguobacterium strains formed two distinct divisions that generally agreed with temperature ranges for growth. With few exceptions (e.g.,
Greenland ice isolate GIC31), psychrotrophic and thermophilic isolates belonged to different divisions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Exiguobacterium PFGE Macroarray Psychrophilic and thermophilic adaptations |
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