Ultrathin mycelia-forming organisms from submarine volcanic areas having an optimum growth temperature of 105 °C

Abstract

The most extremely thermophilic organisms known to date have been isolated from continental volcanic areas^1–3, and grow optimally between 70 and 85 °C. In the hope of finding organisms living at temperatures above 100 °C I have taken samples from the hot sea floor of a submarine solfatara field where, as a result of the high pressures liquid water is found that is hotter than 100 °C. Here I report that, from these samples, I isolated unusual disk-shaped prokaryotic organisms, connected by a network of thin hyphae, which grew at 100 °C in the presence of sulphur, hydrogen and carbon dioxide. The organisms could be successfully transferred to synthetic media and were strict anaerobes, growing optimally at 105 °C and not at all at 80 °C or below. However, they did survive for long periods at 4 °C and −20 °C in the absence of oxygen. During growth, H₂S was formed by sulphur reduction. Due to their extreme oxygen sensitivity, their unusual, irregular shape and primitive volcano-adapted metabolism, the novel organisms may represent a very ancient form of life existing in submarine volcanic areas in a water-supplied oxygen-free habitat, which has not changed for billions of years and which prevents competition with normal life due to prohibitively hot temperatures.