Characterization of Ferroplasma isolates and Ferroplasma acidarmanus sp nov., extreme acidophiles from acid mine drainage and industrial bioleaching environments

Three recently isolated extremely acidophilic archaeal strains have been shown to be phylogenetically similar to Ferroplasma acidiphilum Y-T by 16S rRNA gene sequencing. All four Ferroplasma isolates were capable of growing chemoorganotrophically on yeast extract or a range of sugars and chemomixotrophically on ferrous iron and yeast extract or sugars, and isolate Ferroplasma acidarmanus Fer1(T) required much higher levels of organic carbon. All four isolates were facultative anaerobes, coupling chemoorganotrophic growth on yeast extract to the reduction of ferric iron. The temperature optima for the four isolates were between 35 and 42degreesC and the pH optima were 1.0 to 1.7, and F. acidarmanus Fer1(T) was capable of growing at pH 0. The optimum yeast extract concentration for F. acidarmanus Fer1(T) was higher than that for the other three isolates. Phenotypic results suggested that isolate F. acidarmanus Fer1(T) is of a different species than the other three strains, and 16S rRNA sequence data, DNA-DNA similarity values, and two-dimensional polyacrylamide gel electrophoresis protein profiles clearly showed that strains DR1, MT17, and Y-T group as a single species. F. acidarmanus Fer1(T) groups separately, and we propose the new species F. acidarmanus Fer1(T) sp. nov.