The outer membrane profile was reorganized, anabolic pathways and core as well as energy metabolism were repressed and the alginate regulon and sugar catabolism were activated. At the investigated early time point of cold adaptation, the transcriptome was reprogrammed in almost all functional categories, but the protein profile had still not adapted to the change of living conditions in the cold. Free-living bacteria are frequently exposed

to temperatshifts and nonoptimal growth temperatures. In order to grow at low temperatures, the organism must overcome the growth-diminishing effects of this stress condition, such as Dabrafenib price decreased membrane fluidity, altered redox status, increased stability of RNA and DNA secondary structures and thus a reduced Selleckchem MS-275 efficiency of replication, transcription

and translation (Phadtare, 2004). Cold shock response and adaptation have been studied extensively in bacterial model organisms such as Escherichia coli (Phadtare et al., 1999; Gualerzi et al., 2003; Inouye & Phadtare, 2004) and Bacillus subtilis (Graumann & Marahiel, 1999; Beckering et al., 2002; Weber & Marahiel, 2002; Mansilla & de Mendoza, 2005; Budde et al., 2006; El-Sharoud & Graumann, 2007). Pseudomonas putida strain KT2440 (Bagdasarian et al., 1981; Regenhardt et al., 2002) is another bacterial model organism particularly for environmental microbiology. We recently screened a transposon library for genes that are essential for the survival of P. putida KT2440 at low temperatures (Reva et al., 2006). Life at lower temperature was hampered when the transposon had inactivated key genes that are necessary these for the maintenance of (1) transcription, translation and ribosomal activity, (2) membrane integrity and fluidity and (3) redox status of the cell. Here, we report on the global genomewide response of P. putida KT2440 to a downshift of temperature from 30 to 10 °C at both the mRNA

transcript and the protein level. Transcriptome and proteome analyses were accomplished using deep cDNA sequencing and a gel-free, MS-centered proteomics approach. Pseudomonas putida KT2440 (strain DSM6125) (Bagdasarian et al., 1981) was obtained from DSMZ (Braunschweig, Germany). Bacterial cultures were inoculated from a frozen stock culture and incubated at 30 °C for 8 h at 250 r.p.m. in Luria–Bertani medium. An aliquot of 0.2 mL was added to 20 mL M9 medium (Na2HPO4 33.9 g L−1, KH2PO4 15.0 g L−1, NaCl 2.5 g L−1, NH4Cl 5.0 g L−1, MgSO4 2 mM, CaCl2 0.1 mM, FeSO4·7H2O 0.01 mM, pH 6.8) supplemented with 15 mM succinate as the sole carbon source in a 100-mL flask and incubated overnight at 30 °C. Bacteria were then grown in a 1.5-L batch culture (M9+15 mM succinate) using the BioFlo 110 Fermenter (New Brunswick Scientific Co., Edison, NJ) to ensure constant pH, aeration and agitation. When cultures reached the mid-exponential phase (OD600 nm∼0.8), the temperature was decreased from 30 to 10 °C.