While many people may find 50°C (roughly 120°F) to be quite past their comfort zone, many thermophiles thrive between 45 and 122°C, with the toleration for the higher end (< 75°C) being hyperthermophiles. Thermophiles are organisms that can withstand – and sometimes even require – high temperatures to survive, hence their meaning “heat-loving.”

 Thermophiles are both prokaryotic and eukaryotic, though the microorganisms growing in the most extreme environments are archaea. Hot springs and deep-sea thermal vents can be found throughout the world, but a number of the studied thermophiles are concentrated in Yellowstone National Park, USA.

 What makes thermophiles so interesting is their ability to survive under high temperatures without denaturing their proteins. Thermophiles have special enzymes called extremozymes that are more tightly bound than enzymes at normal temperatures. Additionally, thermophile enzymes tend to have less glycine. Since glycine is the smallest and simplest amino acid, it typically allows proteins to be more flexible. Having less glycine in their structures would allow extremozymes to be more rigid and more resistant against extreme temperatures.

 Since extremozymes are able to function under extreme conditions, these enzymes have become well incorporated in biotechnological applications, such as PCR.

 Photo credit: harrell-enb150.blogspot.com


Life In The Extreme!

Above are two colorized freeze fracture TEMs (transmission electron micrographs) through heat-loving Extremophiles. The round sample at the top is called, Desulfurococcus mobilis and the other, at the bottom, is known as, Thermoproteus tenax. These are considered hyperthermophilic, meaning they are both very high temperature loving species.


Both these samples belong to the Archea Group. These are single-celled microorganisms that have no cell nucleus or any other organelles inside their cells. They were once considered to be forms of primitive bacteria but that has since been updated. Archaeal cells have unique properties separating them from the other two domains of life, Bacteria and Eukaryota. 

Despite this visual similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes, notably the enzymes involved in transcription and translation. Other aspects of archaeal biochemistry are unique, such as their reliance on ether lipids in their cell membranes.

Extremophile bacteria live in extreme conditions such as extreme temperature, pH, pressure and salt environments. These species lives in high-sulphur volcanic habitats or geothermal hot springs. It survives at temperatures up to 90 degrees Celsius (194 degrees F), and thrives optimally at 85 degrees Celsius.

Images above © Wolfgang Baumeister / Science Source