mRNA expression in wild type and TTHA0175-deficient Thermus thermophilus HB8 strains; rich medium with growth temperature shift from 70C to 45C

In order to find function of TTHA0175 protein, we analyzed altered expression profile of the total mRNA of TTHA0175-deficient Thermus thermophilus HB8 strain grown in a rich (TT) medium after shifted down the growth temperature from 70 oC to 45 oC, and compared to that in the cases of wild type. Wild-type and TTHA0175-deficient T. thermophilus HB8 strains were each pre-cultured at 70oC for 16 h 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 (0.3 ml) were inoculated into 0.15 liter of the same medium and then cultivated at 70oC. At the Abs600=0.8 (0min), cold medium was added and the temperature were shifted down to 45oC. Cells were collected at 0, 30, and 120 min after temperature shift, and then crude RNA was extracted. In order to compare mRNA expression between 45oC and 70oC both in the cases of wild-type and TTHA0175-deficient strains, the expression of each mRNA at each time point was analyzed on a GeneChip.