Life in the Extreme: New Prokaryotes Living in High Temperature Low pH Environments

Abstract

There are a number of new organisms that live in acid hot springs that we now know about. These organisms live at about the temperature optimum of Sulfolobus (~70°C) and significantly above that optimum. These organisms grow well below the 105°C temperature optimum of Pyrolobus fumarii, the most extreme thermophile known (Stetter, 1982). The new prokaryotes may belong both to Archaea, like Sulfolobus and to the Bacteria. They were discovered in the acid hot springs of Yellowstone National Park, WY, U.S.A. In hot spring outflow channels with sulfur crystals the presence of Sulfolobus was rapidly confirmed in most samples, and at temperatures below 80°C rod shaped organisms were also present. In mixing pools rods were present at temperatures up to about 89°C. My analysis of these new organisms appears in the sections below.