Differential expression analysis of Thermus thermophilus HB8 wild-type strain in response to NaCl

In order to investigate response of T. thermophilus HB8 wild-type strain for high salt stress, we observed the expression profile of the total mRNA in the strain at 30 min after the addition of NaCl to a final concentration of 0.5% and/or 1.5%, and compared them with that of non-treated cells. Three T. thermophilus HB8 wild-type strains were pre-cultured at 70 degC for 16 hours in 3 mL of TT medium containing 0.8% polypeptone, 0.4% yeast extract, 0.2% NaCl, 0.4 mM CaCl2, and 0.4 mM MgCl2, which was adjusted to pH 7.2 with NaOH. The cells were inoculated into 1 L or 250 ml of TT medium to a 1/500 dilution, and then cultivated at 70°C for 6 hours. Then NaCl was added into the medium to a final concentration of 0.5 or 1.5%, and the cultivation was continued. Cells were collected at 0 and 30 min time point after the addition of excess NaCl, and then crude RNA was extracted. The expression of each mRNA at each time point was analyzed on a GeneChip.