Acidianus infernus gen. nov., sp. nov., and Acidianus brierleyi Comb. nov.: Facultatively Aerobic, Extremely Acidophilic Thermophilic Sulfur-Metabolizing Archaebacteria

Abstract

A new genus, Acidianus, is characterized from studies of 26 isolates of thermoacidophilic archaebacteria from different solfatara fields and marine hydrothermal systems; these isolates grow as facultative aerobes by lithotrophic oxidation and reduction of SO, respectively, and are therefore different from the strictly aerobic Sulfolobus species. The Acidianus isolates have a deoxyribonucleic acid guanine-plus-cytosine content of 31 mol%. In contrast, two of three Sulfolobus species, including the type species, have a guanine-plus-cytosine content of 37 mol%; Sulfolobus brierleyi is the exception, with a guanine-plus-cytosine content of 31 mol%. In contrast to its earlier descriptions, S. brierleyi is able to grow strictly anaerobically by hydrogen-sulfur autotrophy. Therefore, it is described here as a member of the genus Acidianus. The following species are assigned to the genus Acidianus: Acidianus infernus sp. nov. (type strain, strain DSM 3191) and Acidianus brierleyi comb. nov. (type strain, strain DSM 1651).