Characteristics of Acidibacillus Spp.: A Novel Genus of Acidophilic Iron-Oxidising Firmicutes

Strains of acidophilic bacteria, isolated from different global locations, were shown to be representatives of a novel genus within the Firmicutes phylum. All isolates oxidised and reduced iron and catalysed the oxidative dissolution of pyrite. Together they formed two distinct phylogenetic clusters, one of which included mesophilic strains that did not oxidise sulfur, and the other thermotolerant/moderately thermophilic strains that could oxidise sulfur. The novel genus Acidibacillus is proposed for these new isolates, to include A. ferrooxidans (mesophilic iron-oxidising strains) and A. sulfooxidans (moderately thermophilic iron-and sulfur-oxidising strains) as candidate species.