Guan Zhou Qiu

Isolation and characterization of Ferroplasma thermophilum sp. nov., a novel extremely acidophilic, moderately thermophilic archaeon and its role in bioleaching of chalcopyrite

Aims:  To isolate Ferroplasma thermophilum L1T from a low pH environment and to understand its role in bioleaching of chalcopyrite.

Microbial populations in acid mineral bioleaching systems of Tong Shankou Copper Mine, China

Aims:  To understand the composition and structure of microbial communities in different acid mineral bioleaching systems, and to present a more complete picture of microbially mediated acid mine drainage production.

Metagenomic Insights into the Microbial Community Diversity between Leaching Heap and Acid Mine Drainage

The leaching heap and acid mine drainage are two key nodes in a bioleaching system. This study aimed to investigate the microbial community structural and functional diversity between the two nodes in bioleaching system from Dexing copper mine in Jiangxi province, China. 16SrRNA gene cloning and metagenomic analysis consistently indicated that there were obvious differences on microbial community structural and functional diversity in the two nodes. In leaching heap, the dominant species was the heterotrophic bacterium Acidiphilium; while the dominant species was the autotrophic bacterium Acidithiobacillus in acid mine drainage. Seven bacteria species were found in both two nodes, while the unique bacteria species in leaching heap and acid mine drainage were eleven and eight, respectively. In relation to the microbial community function aspect, all contigs and singlets were annotated against the non-redundant protein database of NCBI and clustering analyzed with COG database. For the two nodes, the COG clustering results showed that the functional category abundances were different, though the functional categories were similar. And the great majority of ORFs were forecasted as function unknown. All the results meant that the microbial community structural and functional diversity of bioleaching system was not as simple as former thought. This study could provide a new meta-view of theoretical support to bioleaching process.

Synthesis and Magnetic Properties of Fe–Ni Alloy Nanoparticles Obtained by Hydrothermal Reaction

The magnetic properties of Fe-Ni alloy nanoparticles with particle size in the range 35-45 nm were prepared by almost simultaneously reducing Fe(II) and Ni(II) solution using hydrazine hydrate as a reducing agent in strong alkaline media for two hours at 80 °C. Chemical composition, crystal structure, morphology, thermal stability and magnetic properties of as synthesized Fe-Ni alloy nanoparticles were systematically characterized by means of XRD, TEM, TG-DSC and VSM. These results indicate that there is a vitally important relationship among particle size, particle morphology, and different mol ratio of FeSO4 to NiSO4. The saturation magnetization (Ms). and coercivity (Hc) strongly affected by the composition of Fe-Ni alloy nanoparticles. The hydrothermal reaction is a simple, effective, and low-cost synthetic method to prepare FeNi3 alloy nanoparticles.

Electrochemical Behavior of Massive Bornite Bioleached Electrodes in the Presence of Acidithiobacillus Ferrooxidans and Acidithiobacillus Caldus

In this work, the monitoring of bacterial and chemical dissolution of massive bornite was performed using cyclic voltammetry (CV); the mineral surface was examined using scanning electron microscopy (SEM) and the elements were indentified by Energy Dispersive X-ray Analysis (EDXA). The electrolyte employed for the electrochemical tests was the medium used for bioleaching the electrodes (3.0 g•dm-3 (NH4)2•SO4, 0.5 g•dm-3K2HPO4, 0.5 g•dm-3 MgSO4•7H2O and 0.1 g•dm-3 Ca(NO3)2).The results showed differences in voltagramms carried out by Acidithiobacillus ferrooxidans and Acidithiobacillus caldus: In bioleached electrodes tested in the presence of Acidithiobacillus ferrooxidans, the anodic and cathodic current signals were larger than with Acidithiobacillus caldus The analysis of CV results allowed attributing the different peaks observed in both the direct and reverse potential scanning to the oxidation of bornite to a secondary copper mineral(chalcocite and covellite) and its reduction via different non stoichiometric copper sulphides intermediaries. Surface evidences were produced by SEM, and chemical elements evidences were also investigated by EDAX.

Isolation, Characterization and Phylogenetic Analysis of Acidiphilium-Like Bacteria from Acid Mine Drainage

The acidophilic heterotrophic bacteria Acidiphilium spp. were considered as a ministrant of Leptospirillum spp., Acidithiobacillus spp. and other autotrophic bacteria in acid mine drainage (AMD). 25 Acidiphilium-like bacterial strains were isolated from eight different mines in China and their physiology was characterized. Their marmatite-bioleaching ability has been investigated and compared with that of a mixed culture of Acidiphilium sp. and Acidithiobacillus ferrooxidans. The results indicated that some Acidiphilium-like strains exhibited a high marmatite-bioleaching ability, which was even higher than that of Acidithiobacillus ferrooxidans. The leaching efficiency was not higher in mixed than in pure culture. The phylogenetic relationship of the 25 Acidiphilium-like strains was analyzed by 16S rRNA sequencing, GyrB sequencing and rep-PCR genomic fingerprinting. The 25 strains and other eight species of Acidiphilium spp. were clustered into three groups.

Comparative Study of Fluoride-Tolerance of Five Typical Bioleaching Microorganisms

In the bioleaching of uranium ore, fluoride that ever accreted with the ore floats into solution, inhibiting the growth and metabolic processes of microorganism or even killing them, further reducing the efficiency of uranium leaching. In order to study the fluoride tolerance of the bioleaching microorganisms, five typical bioleaching strains including Acidithiobacillus ferrooxidans ATCC 23270, Leptospirillum ferriphilum YSK, Sulfobacillus thermosulfidooxidans ST, Acidithiobacills thiooxidans A01, Acidithiobacills caldus S1 were selected to compare their growth fluctuation and their oxidation rate of iron or sulfur in the presence of different concentration of fluoride. The results showed that At. ferrooxidans ATCC 23270 held the best fluoride tolerance, while S. thermosulfidooxidans ST took the worst. In order to explore the mechanism of microbial resistance to fluoride, whole-genome array (WGA) was used to analyze the genome-wide expression profiling of At. ferrooxidans ATCC 23270 upon 4.8 mM fluoride stress. The results showed that gene categories closely related to fluoride tolerance include cell membrane, energy metabolism, transport and binding functions of proteins, DNA metabolism, cell processing, synthesis and transportation of protein and other functional and metabolic pathways. Most of the genes associated with iron-sulfur metabolic system of At. ferrooxidans were highly expressed during 10 to 120 minutes, while in the long-term stress for 4 hours, the gene expression returned to normal level or even were down regulated. All these results provide useful information for further research on domesticating bacteria and increasing the efficiency of uranium leaching.

Microbial Communities in Acid Mine Water from Two Different Copper Mines in China

Microorganisms such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans are the most studied acid mine drainage (AMD) organisms, they catalyze ferrous iron oxidization, thus determine the rate of metal sulfide dissolution, and play very important roles in AMD generation. To present a more complete picture of microbially mediated AMD production, the composition of microbial communities in five AMD samples was determined using a culture-independent 16S rDNA based cloning approach. Three samples, named SX1, SX2 and SX3, were obtained from three separate AMD sites of the Zhong Tiaoshan copper mine in Shanxi Province, China. The other two samples, named K1 and K2, were obtained from two separate bioleaching systems of the Tong Shankou copper mine, Hubei Province, China. Phylogenetic analysis revealed that the bacteria in these five samples fell into four major groups: Proteobacteria (α-, β-, γ-, δ-proteobacteria), Nitrospira (Leptospirillum), Firmicutes and Bacteroidetes. Proteobacteria such as A. ferrooxidans and A. albertensis dominated in the samples SX2, SX3, K1 and K2, but were scarce in sample SX1; Nitrospira such as Leptospirillum ferrooxidans, Leptospirillum ferriphilum and Leptospirillum group lll, were prevalent in the samples SX1, SX3, K1 and K2, but scarcely occurred in sample SX2; Firmicutes were only found in the samples SX3 and K1; Bacteroidetes were only found in the sample SX3. Archaea were only detected in the two samples K1 and K2 from the Tong Shankou copper mine. Thermoplasma and Ferroplasma lineages were detected abundantly in these two samples. Unexpectedly, sequences affiliated with Sulfolobales and the genus Methanothermus were also detected in small numbers. The results of a PCA (Principal Component Analysis) suggested that biogeochemical properties of the samples correlated with the microbial community structure in these samples. Additionally, the concentrations of some elements such as S, Fe, Cu, Zn and Ag seemed to be key factors resulting in the diverse distribution of typical iron-oxidizers (such as Acidithiobacillus ferrooxidans and Leptospirillum species) in different water samples. The fluorescence in situ hybridization (FISH) method was also used to investigate microbes in the samples K1 and K2. The variation in the intensity of the hybridization signals from different probes (such as CY3 labeled probe TF539, FAM labeled probe LF655, CY3 labeled probe FER656, FAM labeled ARCH915 and CY5 labeled ACD840) indicated the difference of microbes’ distribution in different environments, which may prove some results revealed by RFLP. Advanced Materials Research Online: 2007-07-15 ISSN: 1662-8985, Vols. 20-21, pp 577-577 doi:10.4028/www.scientific.net/AMR.20-21.577

Output Work of the Electro-Generative Simultaneous Leaching for Sphalerite-MnO2 in the Presence of Acidithiobacillus ferrooxidans

Sphalerite was used to study both the electro-generative simultaneous leaching (EGSL) and the bio-electro-generative simultaneous leaching (BEGSL) in this paper. The Relationship between potential, work output, and current for sphalerite in presence of A. Ferrooxidans and sterile, showed that the electro-generation trend enhanced in the presence of A. ferrooxidans for sphalerite. The Evans graph for sphalerite in presence of A. ferrooxidans and sterile showed that with the increase of current, the output potential decreased. The dissolved metal ion in the presence of A. ferrooxidans is nearly 30% higher than that in the absence of A. ferrooxidans; the electro-generative quantity in the former is about 130% more than that in the latter; the transferred charge due to the bacteria is more than that of EGSL process in the last stage of BEGSL.

Optimization of the Method for Simultaneous Extraction Bioleaching Bacteria DNA and RNA

Metagenomic and metatrascription technologies were developed rapidly and applied widely in environmental microbiology in recent years and were also gradually applied in biohydrometallurgy. However, how to get good quality DNA and RNA simultaneously is still the key factor to determine the success and relibility of the whole data analysis. In this study, a wide used DNA extraction method [ was optimized for extraction of crude nucleic acid from acidic habitat. Our results showed that nucleic acid extraction buffer (pH 7.0) contain PIPES salt could effectively extract crude nucleic acid (including DNA and RNA) from four pure culture and several acidic environmental samples. Qiagen DNA and RNA isolation system (All prep DNA/RNA Mini kit) could separate DNA and RNA. Good quality with A260/280 was around 1.87±0.01 for total 33.88±7.85 μg DNA and A260/230 around 2.07±0.07 for total 20.00±2.73 μg RNA were obtained from 300 mL A.f culture medium (strain concentration was around 2×107). All isolated DNA and RNA could be used for downstream molecular analysis. This study provides a useful method for simultaneous extraction, separation and purification DNA and RNA from acidic habitat, which could accelerate the quantitative analysis for biohydrometually and therefore increase the efficiency of biohydrometually.