Affitins are derived from Sul7d proteins which are hosted by Sulfolobus, Acidianus and Metallosphaera archaea. During a trip to Italy in 2016, we could not help but visit the famous Solfatara crater near the city of Pozzuoli!

The archaeal specie Sulfolobus solfataricus was first discovered in 1980 there. In the main area of the crater, one can see Bocca Grande and Bocca Nuova fumaroles with sulfur deposits where temperatures are very high (up to 160°C). The optimal temperature for growth of Sulfolobus solfataricus is around 80°C with a pH between 2 and 4. In fact, it’s in the backside of the crater that Karl Setter and Wolfram Zillig isolated samples from a small field, called Pisciarelli, in steam-heated acidic water holes. In these holes, the temperature is more “Sulfolubus friendly”: between 95 and 110°C…

Sulfolobus acidocaldarius, another well-studied specie, was the first Sulfolobus to be described (1972). It was discovered by Thomas D. Brock and his collaborators in Yellowstone park (USA).

Photos by Barbara Mouratou & Frédéric Pecorari