Architecture of thermal adaptation in an Exiguobacterium sibiricum strain isolated from 3 million year old permafrost: A genome and transcriptome approach




Rodrigues, Debora F.
Ivanova, Natalia
He, Zhili
Huebner, Marianne
Zhou, Jizhong
Tiedje, James M.

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BMC Genomics


Background: Many microorganisms have a wide temperature growth range and versatility to tolerate large thermal fluctuations in diverse environments, however not many have been fully explored over their entire growth temperature range through a holistic view of its physiology, genome, and transcriptome. We used Exiguobacterium sibiricum strain 255-15, a psychrotrophic bacterium from 3 million year old Siberian permafrost that grows from -5°C to 39°C to study its thermal adaptation. Results: The E. sibiricum genome has one chromosome and two small plasmids with a total of 3,015 protein-encoding genes (CDS), and a GC content of 47.7%. The genome and transcriptome analysis along with the organism's known physiology was used to better understand its thermal adaptation. A total of 27%, 3.2%, and 5.2% of E. sibiricum CDS spotted on the DNA microarray detected differentially expressed genes in cells grown at -2.5°C, 10°C, and 39°C, respectively, when compared to cells grown at 28°C. The hypothetical and unknown genes represented 10.6%, 0.89%, and 2.3% of the CDS differentially expressed when grown at -2.5°C, 10°C, and 39°C versus 28°C, respectively. Conclusion: The results show that E. sibiricum is constitutively adapted to cold temperatures stressful to mesophiles since little differential gene expression was observed between 4°C and 28°C, but at the extremities of its Arrhenius growth profile, namely -2.5°C and 39°C, several physiological and metabolic adaptations associated with stress responses were observed.



Glycine Betaine, Amino Acid Biosynthesis, Thermal Adaptation, Siberian Permafrost, Dethiobiotin


Copyright 2008 BMC genomics. Recommended citation: Rodrigues, Debora F., Natalia Ivanova, Zhili He, Marianne Huebner, Jizhong Zhou, and James M. Tiedje. "Architecture of thermal adaptation in an Exiguobacterium sibiricum strain isolated from 3 million year old permafrost: a genome and transcriptome approach." BMC genomics 9, no. 1 (2008): 547. DOI: 10.1186/1471-2164-9-547 URL: Reproduced in accordance with the original publisher’s licensing terms and with permission from the author(s).