This Article Full Text Full Text (PDF) Supplemental material Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bergholz, P. W. Articles by Tiedje, J. M. Search for Related Content PubMed PubMed Citation Articles by Bergholz, P. W. Articles by Tiedje, J. M. Pubmed/NCBI databases GEO DataSet

 Previous Article  |  Next Article 

Journal of Bacteriology, April 2009, p. 2340-2352, Vol. 191, No. 7
0021-9193/09/$08.00+0     doi:10.1128/JB.01377-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Psychrobacter arcticus 273-4 Uses Resource Efficiency and Molecular Motion Adaptations for Subzero Temperature Growth ^,

Peter W. Bergholz,^* Corien Bakermans , and James M. Tiedje

NASA Astrobiology Institute Center for Genomic and Evolutionary Studies on Microbial Life at Low Temperature and Center for Microbial Ecology, Michigan State University, East Lansing, Michigan

Received 1 October 2008/ Accepted 6 January 2009

Permafrost soils are extreme environments that exert low-temperature, desiccation, and starvation stress on bacteria over thousands to millions of years. To understand how Psychrobacter arcticus 273-4 survived for >20,000 years in permafrost, transcriptome analysis was performed during growth at 22°C, 17°C, 0°C, and –6°C using a mixed-effects analysis of variance model. Genes for transcription, translation, energy production, and most biosynthetic pathways were downregulated at low temperatures. Evidence of isozyme exchange was detected over temperature for D-alanyl-D-alanine carboxypeptidases (dac1 and dac2), DEAD-box RNA helicases (csdA and Psyc_0943), and energy-efficient substrate incorporation pathways for ammonium and acetate. Specific functions were compensated by upregulation of genes at low temperature, including genes for the biosynthesis of proline, tryptophan, and methionine. RNases and peptidases were generally upregulated at low temperatures. Changes in energy metabolism, amino acid metabolism, and RNase gene expression were consistent with induction of a resource efficiency response. In contrast to results observed for other psychrophiles and mesophiles, only clpB and hsp33 were upregulated at low temperature, and there was no upregulation of other chaperones and peptidyl-prolyl isomerases. relA, csdA, and dac2 knockout mutants grew more slowly at low temperature, but a dac1 mutant grew more slowly at 17°C. The combined data suggest that the basal biological machinery, including translation, transcription, and energy metabolism, is well adapted to function across the growth range of P. arcticus from –6°C to 22°C, and temperature compensation by gene expression was employed to address specific challenges to low-temperature growth.

---

* Corresponding author. Present address: 709 Bradfield Hall, Department of Crop and Soil Science, Cornell University, Ithaca, NY 14853. Phone: (517) 449-5943. Fax: (607) 255-8615. E-mail: pwb49{at}cornell.edu

Published ahead of print on 23 January 2009.

Supplemental material for this article may be found at http://jb.asm.org/.

Present address: Department of Earth Sciences, Montana State University, Bozeman, MT.

---

Journal of Bacteriology, April 2009, p. 2340-2352, Vol. 191, No. 7
0021-9193/09/$08.00+0     doi:10.1128/JB.01377-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.