With the aid of a high-speed and high-sensitivity camera, biologists at the University of Regensburg have recorded the movement of a type of microorganism called Archaea.
Archaea thrive at temperatures between 80°C and 100°C and, to study live cells and understand how they move, the scientists at the department of microbiology designed a thermal microscope where the mechanical stage can be heated to 95°C. A fluorescent dye was used to visualise the cell flagella responsible for movement.
The Archaea species Methanothermobacter thermautotrophicus studied only emits weak fluorescence, so the camera had to be very sensitive. It also had to have a high scanning frequency to be able to follow the fast-swimming microorganisms, which can travel 200 times the length of their body in one second.
Cameras from PCO were used, including the pco.1200 hs which has a frame rate of 100 images per second and is fast enough to continuously film the microorganisms at such speeds. Based on the magnification scale of the microscope it is possible to calculate the distances travelled by the Archaea from one frame to the next.
The microbiologists at the University of Regensburg discovered two ‘swimming styles’. First the microorganisms jet through the water at high speed, travelling long distances in search of a suitable living environment in their biotope. It is assumed that they use the temperature gradient for orientation. Once they have found a suitable location, they slow down swimming at one-tenth of their original speed in zigzag patterns, apparently searching for a place to cling to the wall of the test tube. The team found out that the Archaea use the same organelles for both types of motion as well as for adhesion.
The team’s work is purely basic research, according to Professor Reinhard Wirth, who led the study. Nevertheless, there are aspects that could be economically valuable – the adhesive used by the Archaea to hold onto surfaces, for example, remains sticky even in boiling water, which is a property with potential for many technical applications, such as gluing silicon in microchips that become hot during operation.
