Metallosphaera tengchongensis sp. nov., an acidothermophilic archaeon isolated from a hot spring

Two novel acidothermophilic archaea, strains Ric-A ᵀ and Ric-F, were isolated from muddy water samples of a sulfuric hot spring located in Tengchong County, Yunnan Province, PR China. The strains were aerobic and facultatively chemolithoautotrophic. Both strains could oxidize S ⁰ and K ₂S ₄O ₆ for autotrophic growth, and could use organic materials for heterotrophic growth. Growth was observed at 55–75 °C and pH 1.5–6.5. The strains could oxidize metal sulfide ores, showing their potential in bioleaching. The DNA G+C contents of strains Ric-A ᵀ and Ric-F were 41.8 and 41.6 mol%, respectively. Analysis of 16S rRNA gene sequences showed that the two strains shared 99.8 % sequence similarity to each other, but