Pyrobaculum gen. nov., a new genus of neutrophilic, rod-shaped archaebacteria from continental solfataras growing optimally at 100�C

Six isolates of a new genus of anaerobic archaebacteria, named Pyrodictium, were isolated from a submarine solfataric field off Vulcano, Italy. These disc-shaped organisms grew at at least 110°C with an optimum around 105°C, and formed highly unusual networks of fibres. They were hydrogen-sulphur-autotrops. During growth in a fermenter, pyrite was formed. Two species can be distinguished: Pyrodictium occultum - which has a G + C-content of 62 mol%, and, as the dominant component in its cell envelope, a glycoprotein with a molecular weight of 172000 - and Pyrodictium brockii - which has a G + C-content of 51.5 to 56.6 mol%, a protein of molecular weight 150000 as its major cell envelope component, and whose growth yield is greatly increased in the presence of yeast extract. Copyright © 1983 Gustav Fischer Verlag, Stuttgart/New York. Published by Elsevier GmbH.. All rights reserved.