Isolation and characterization of Acidiphilium strain Teng-A and its metabolism of Fe(Ⅲ) during pure- and mixed cultivation

Abstract:

An acidophilic, aerobic and chemoheterotrophic bacterial strain Teng-A was isolated from acidic environmental samples collected at sulfidic hot springs of Tengchong County, Yunnan Province, China. Cells of strain Teng-A was rod-shaped (0.6～0.8 μm×1.0～1.5 μm), Gram-negative, motile with flagella. Strain Teng-A grew well at temperature of 29～33oC and at pH of 3.0～4.0. It used a wide variety of organic compounds for growth, but did not use ferrous iron, elemental sulfur, thiosulfate and tetrathionate as the sole energy source. Its G+C content was determined to be 69.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequence demonstrated that it was closely related to species of Acidiphilium. Under anoxic conditions, the strain Teng-A reduced Fe(Ⅲ)to Fe(Ⅱ) with glucose or hy drogen as electron donor (reduction rate is 11.56mg/L·day and 15.34mg/L·day, respectively). Metabolisms/Oxidation of ferrous iron by Acidithiobacillus ferrooxidans LJ-1 and Leptospirilum ferriphilum LJ-2, in the presence and absence of strain Teng-A were studied. When incubated with strain Teng-A, the oxidation rates of Fe(Ⅱ) was slightly decreased at the first 3 days (0.44g/L·day and 0.41g/L·day respectively) compared to pure culture of At ferrooxidans and L. ferriphilum, but all Fe(Ⅱ) was completely oxidized after 5 days. It was found that the morphologies of precipitates of Fe(Ⅲ) produced during pure and mixed cultivation were different. The potential application of Acidiphilium in bioleaching and its potential role during formation of precipitated ores were discussed.