Isolation, characterization of Acidiphilium sp. DX1-1 and ore bioleaching by this acidophilic mixotrophic organism

The isolation and characterization of a subspecies of Acidiphilium that not only acts as an enhancer of other autotrophic acidophiles in bioleaching, but also has significant leaching capacity towards marmatite was described. Acidiphilium sp. DX1-1, a Gram-negative, motile, short rod-shaped bacterium that accumulates intracellular polyhydroxybutyrate, was isolated from the Dexing copper mine area in China. It is mesophilic and acidophilic with an optimum growth at 30 °C and pH 3.5. Phylogenetic analyses identify that it is a member of genus Acidiphilium and closely related to Acidiphilium cryptum and Acidiphilium multivorum. It is mixotrophic, utilizing organic substrates and a range of inorganic substrates, such as sulfur, ferric iron and a variety of sulfide minerals. Acidiphilium sp. DX1-1 is able to bioleach 40% of the zinc content of marmatite with the initial pH 3.5 within a month, which is even higher than that of A. ferrooxidans or the mixed culture with A. ferrooxidans at even lower pH.