Flow-type apparatus for studying thermotolerance of hyperthermophiles under conditions simulating hydrothermal vent circulation

A flow-type apparatus has been developed to study thermotolerance of microorganisms under conditions simulating submarine hydrothermal circulation. The apparatus is designed so that microorganisms can be exposed to high temperature for periods of only a few seconds duration, and can be operated at temperatures up to 400 °C and hydrostatic pressures up to 30 MPa, even under strict anaerobic conditions. The performance of the apparatus was tested by studying the thermotolerance of a mesophilic bacterium, Escherichia coli strain W3110, after heat treatment at temperatures between 59.0 and 64.5 °C for 1.5 s. The results compared favorably with the literature data obtained by a conventional batch method at lower temperatures and longer heating durations. Thermotolerance of a hyperthermophilic archaeon, Pyrococcus horikoshii strain OT3, was successfully determined by the apparatus at temperatures up to 119 °C and pressures up to 25 MPa under anaerobic conditions.