BACILLUS-TUSCIAE, A NEW SPECIES OF THERMOACIDOPHILIC, FACULTATIVELY CHEMOLITHOAUTOTROPHIC, HYDROGEN OXIDIZING SPOREFORMER FROM A GEOTHERMAL AREA

A thermophilic, chemolithoautotrophic, H2-oxidizing sporeformer was isolated from ponds in a solfatara in the geothermal area of Tuscany (Italy). Some physicochemical parameters of the habitat were determined. The habitat was characterized by the presence of H2 in the escaping gases, a very low content of phosphate and organic matter. Temperature and water level in the ponds varied widely. The organism formed oval, subterminal spores, which swelled distinctly the sporangium. Optimal growth occurred between pH 4.2-4.8 at 55.degree. C. It grew best under autotrophic conditions, but organic substrates including short chain fatty acids, amino acids and alcohols could also support heterotrophic growth. Sugars were not metabolized. The hydrogenase was soluble but did not reduce pyridine nucleotides. Based on its morphological and biochemical features, the organism belongs to the genus Bacillus, but differs from all the previously described species; it is proposed as constituting a new species, B. tusciae.