Going to the extreme
05 Jul 2014



For most of us, temperatures around the mid-twenties and a light breeze, sounds like the ideal environment - anything over or under this happy medium and we start to feel a little under pressure.


​​Extremophiles thrive in some of the most extreme environments around. Credit: Dreamstime​


But some bacteria are able to take the heat - and the cold! Whilst facing even more extreme kinds of high pressure.These organisms are appropriately named Extremophiles as they thrive in some of the most extreme environments around whether it’s boiling deep-sea vents, deep under desert rocks or in some really salty places like animal intestines.

One branch of this extreme team, known as piezophiles, has caught the eye of a group of scientists from the University College London. These organisms are generally found on ocean floors which have an average depth of 3800m and where temperatures reach a chilling two degrees. This light lacking deep sea den is also home to extreme pressures, which hit around 38MPa, and so scientists want to understand the novel ways in which bacteria have adapted in order to become tolerant of these pressures and be able to colonise these deep sea habitats.

Dr. Fabrizia Foglia, University College London, explains, ‘Piezophillic organisms are extraordinary because they can function and survive under extreme pressure conditions. For example, some bacteria have been found to survive up to 110MPa in deep sea floor environments. It’s critically important that we can understand how bacterial life can function under such extreme conditions as these and to do this we are studying the membrane structure of live bacteria under high pressure.’

The team want to see how high pressure works in live organisms in order to compare what happens to mesophile bacteria compared with extremophiles. Mesophile bacteria are different in that they grow best at moderate temperatures between 20-45degrees and they are often used in the process of beer and wine making.

One of the reasons the team are interested to study these bacteria under high pressure is that in the food industry high hydrostatic pressure technology is finding increased application because it doesn’t use heat and has the ability to inactivate microorganisms and well as enzymes which would otherwise shorten life of the product. So the team want to see how affective pressure is on killing these bacteria and whether it is possible for the bacteria to become pressure adapted and in doing so behaving more like the extremophiles.

Any one for rocks?

 ‘The bacteria we are working with, Shewanella oneidensis MR-1, is a mesophile bacterium and is very versatile because it can grow with and without oxygen.’ explains Fabrizia. ‘In anaerobic conditions these bacteria use metals to produce their own energy – so basically eating rocks!’

By looking at the reactions that appear on the Membrane you can tell a lot about an organism and so the Team have been using Quasi-elastic neutron scattering to look at the diffusion of water across the membrane at high pressure to see how the membrane reacts and what changes they can observe.

‘Bacteria can adapt to high pressure and this is what we are interested in studying. What we have are two strains the wild type and then we have generated a pressure adapted a strain of the bacteria which we make in the lab. We are now using neutrons to look at the difference between the two at very high pressures to see if the pressure affects the structure and the death rate of these bacteria.’

Some survive better, down where there’s pressure, under the sea

The Mariana Trench is the deepest point known to date – 11000m in depth and with a pressure maximum around 100MPa. The Team are looking these pressures and even more extreme pressures. They used the IRIS spectrometer at ISIS to look at how the structure of the membrane changes as the pressure is increased from 200 to 500 MPa. The results so far are looking promising.

‘What we are recording is survivor cells; a very small population can adapt, this is interesting because shewanella is a mesophile bacterium so it grows at normal pressure and temperature conditions however we know that it contains the genotype of the piezophiles and pressure resistant species. So we are hoping to do some protein studies on the bacteria and also some genomic studies in the future to look at this further and see if this is the case.’

Felice Laake

Research date: July 2014

Further Information

For further information please contact Dr. Fabrizia Foglia