The heat shock response in meso- and thermoacidophilic chemolithotrophic bacteria

The heat shock response was studied in a chemolithotrophic thermoacidophilic archaebacterium Sulfolobus acidocaldarius (shifted from 70° to 85°C) and a mesoacidophilic microorganism Thiobacillus ferrooxidans (from 30° to 41°C). When transferred from their normal growth temperature to the stress temperature, cells showed a decrease in the incorporation of Na214CO3 into proteins, and at the same time, the synthesis of a specific subset of heat shock proteins was observed. Ethanol (4%) at 30°C, also caused a response similar to the heat shock upon T. ferrooxidans cells, whereas Sulfolobus cells at 70°C did not incorporate radioactive CO2 in the presence of ethanol, apparently being damaged by the organic solvent.