Real-time PCR analysis of the heat-shock response of Acidithiobacillus ferrooxidans ATCC 23270.

As one of the most important bioleaching bacterial species, Acidithiobacillus ferrooxidans is subjected to different kinds of environmental stress such as temperature changes, presence of some toxic heavy metals or pH changes, which normally take place in bioleaching operations and may affect the activity of the bacteria. To obtain further knowledge of the protective mechanisms employed by A. ferrooxidans in response to elevated growth temperature, temporal gene expression profiles were examined in cells subjected to heat stress by using real-time PCR. The majority of predicted genes, including those encoding chaperones and heat-shock proteins, were significantly up-regulated (P < 0.05 and the fold change >or= 2.0) over a 25-min period after upshift to the heatshock temperature (from 30 to 42 degrees C) and then decrease to readjust their transcript levels to a new steady state at 42 degrees C. Finally, based on the gene expression data and computational analysis, a putative regulatory site having T-T-T-T-T-T-n-n in the -35 region and n-T-A-T-n-A-T-C in the -10 region with average 19 base pairs separating the two elements was predicted upstream of a number of heat-inducible genes.