Generation of acid mine drainage around the Karaerik copper mine (Espiye, Giresun, NE Turkey): implications from the bacterial population in the Acisu effluent.

The Karaerik Cu mine is a worked-out deposit with large volumes of tailings and slags which were left around the mine site without any protection. Natural feeding of these material and run-off water from the mineralised zones into the Acisu effluent causes a serious environmental degradation and creation of acid mine drainage (AMD) along its entire length. This research aims at modelling the formation of AMD with a specific attempt on the characterisation of the bacterial population in association with AMD and their role on its occurrence. Based on 16SrRNA analyses of the clones obtained from a composite water sample, the bacterial community was determined to consist of Acidithiobacillus ferrivorans, Ferrovum myxofaciens, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans as iron-oxidising bacteria, Acidocella facilis, Acidocella aluminiidurans, Acidiphilium cryptum and Acidiphilium multivorum as iron-reducing bacteria, and Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Acidiphilium cryptum as sulphur-oxidising bacteria. This association of bacteria with varying roles was interpreted as evidence of a concomitant occurrence of sulphur and iron cycles during the generation of AMD along the Acisu effluent draining the Karaerik mine.

Acidiphilium iwatense sp. nov., isolated from an acid mine drainage treatment plant, and emendation of the genus Acidiphilium.

Several strains of aerobic, acidophilic, chemo-organotrophic bacteria belonging to the genus Acidiphilium were isolated from an acid mine drainage (AMD) (pH 2.2) treatment plant. 16S rRNA gene sequence comparisons showed that most of the novel isolates formed a phylogenetically coherent group (designated Group Ia) distinguishable from any of the previously established species of the genus Acidiphilium at <98% similarity. This was supported by genomic DNA-DNA hybridization assays. The Group Ia isolates were characterized phenotypically by an oval cell morphology, non-motility, growth in the range pH 2.0-5.5 (optimum pH 3.5), lack of photosynthetic pigment and the presence of C19:0 cyclo ω8c as the main component of the cellular fatty acids and ubiquinone-10 as the major quinone. On the basis of these data, the name Acidiphilium iwatense sp. nov. is proposed to accommodate the Group Ia isolates, and the description of the genus Acidiphilium is emended. The type strain of Acidiphilium iwatense sp. nov. is MS8(T) ( =NBRC 107608(T)=KCTC 23505(T)).

Microbial diversity in acid mine drainage of Xiang Mountain sulfide mine, Anhui Province, China.

To understand the composition and structure of microbial communities in acid (pH 3.0) mine drainage (AMD) associated with pyrite mine tailings in Anhui Province, China, molecular diversities of 16S rRNA and 18S rRNA genes were examined using a PCR-based cloning approach. Bacterial, archaeal and microeukaryotic clone libraries were constructed. In contrast to typical dominance of autotrophic acidophiles, genus Acidiphilium, which consists of mixotrophic acidophiles capable of chemoorganotrophic and photosynthetic metabolisms, was the largest group in the bacterial clone library. These mixotrophic organisms may be advantageous in the oligotrophic AMD environment of the study site (certain amounts of dissolved organic carbon and light) by switching between two modes of metabolisms. Unexpectedly, a large fraction of bacterial clones (12.7%) were related to the neutrophilic genus Legionella, which can cause Legionnaires' disease, a potentially lethal pneumonia. The eukaryotic 18S rRNA gene sequences were mostly related to Oxytricha, Nuclearia, and Penicillium. In the archaeal clone library, all the sequences were affiliated to the phylum Crenarchaeota, while the Euryarchaeota was not present.

Isolation and characterization of ferrous- and sulfur-oxidizing bacteria from Tengchong solfataric region, China.

Microbial oxidation and reduction of iron and sulfur are important parts of biogeochemical cycles in acidic environments such as geothermal solfataric regions. Species of Acidithiobacillus and Leptospirillum are the common ferrous-iron and sulfur oxidizers from such environments. This study focused on the Tengchong sofataric region, located in Yunnan Province, Southwest China. Based on cultivation, 9 strains that grow on ferrous-iron and sulfuric compounds were obtained. Analysis of 16S rRNA genes of the 9 strains indicated that they were affiliated to Acidithiobacillus, Alicyclobacillus, Sulfobacillus, Leptospirillum and Acidiphilium. Physiological and phylogenetic studies indicated that two strains (TC-34 and TC-71) might represent two novel members of Alicyclobacillus. Strain TC-34 and TC-71 showed 94.8%-97.1% 16S rRNA gene identities to other species of Alicyclobacillus. Different from the previously described Alicyclobacillus species, strains TC-34 and TC-71 were mesophilic and their cellular fatty acids do not contain omega-cyclic fatty acids. Strain TC-71 was obligately dependent on ferrous-iron for growth. It was concluded that the ferrous-iron oxidizers were diversified and Alicyclobacillus species were proposed to take part in biochemical geocycling of iron in the Tengchong solfataric region.

[Isolation and characterization of Acidiphilium strain teng-A and its metabolism of fe (III) during pure- and mixed cultivation].

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 microm x 1.0 - 1.5 microm), Gram-negative, motile with flagella. Strain Teng-A grew well at temperature of 29-33 degrees C 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 11.56 mg/L day and 15.34 mg/L x 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 (0.44 g/L x day and 0.4 g/L x 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.