Relationship of critical temperature to macromolecular synthesis and growth yield in Psychrobacter cryopegella

Low-temperature growth of Shewanella oneidensis MR-1

Shewanella oneidensis MR-1 is a mesophilic bacterium with a maximum growth temperature of approximately 35 degrees C but the ability to grow over a wide range of temperatures, including temperatures near zero. At room temperature ( approximately 22 degrees C) MR-1 grows with a doubling time of about 40 min, but when moved from 22 degrees C to 3 degrees C, MR-1 cells display a very long lag phase of more than 100 h followed by very slow growth, with a doubling time of approximately 67 h. In comparison to cells grown at 22 degrees C, the cold-grown cells formed long, motile filaments, showed many spheroplast-like structures, produced an array of proteins not seen at higher temperature, and synthesized a different pattern of cellular lipids. Frequent pilus-like structures were observed during the transition from 3 to 22 degrees C.

Cold Adaptation of the Antarctic Archaeon, Methanococcoides burtonii Assessed by Proteomics Using ICAT

Using isotope coded affinity tag (ICAT) chromatography and liquid chromatography-mass spectrometry, 163 proteins were identified from the cold-adapted archaeon, Methanococcoides burtonii. 14 proteins were differentially expressed during growth at 4 degrees C and 23 degrees C. Knowledge of protein abundance, protein identity and gene arrangement was used to determine mechanisms of cold adaptation. Growth temperature was found to affect proteins involved in energy generation and biosynthesis linked to methanogenesis, membrane transport, transcription and protein folding, as well as affecting the expression of two hypothetical proteins. Pooling the data from this ICAT study with data from a previous two-dimensional gel electrophoresis study highlighted consistencies and differences between the two methods, and led us to conclude that the two approaches were generally complementary. This is the first report of ICAT applied to Archaea, or for the study of cold adaptation in any organism.