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Yang Y.,Central South University | Yang Y.,Key Laboratory of Biometallurgy | Wang X.,Central South University | Shi J.,Central South University | Li J.,Central South University
World Journal of Microbiology and Biotechnology

Human activities have a tremendous impact not only on the macroscopic world, but also on the micro-organisms. Here, Amplified Ribosomal DNA Restriction Analysis (ARDRA) was used for assessing the effect of the industrial sewage on the microbial community in sludge of Dongting Lake, the second-largest freshwater lake in China. The sludge samples from the outfall of the representative nitrogenous fertilizer plant near the lake were collected in March, 2010, and the sludge samples from the surrounding waters were treated as the control. The multi-element analysis results showed that the content of nitrogen, phosphorus in Sample SY were 1. 9 and 1. 47 times of the control group respectively. Based on restriction patterns derived from ARDRA, 26 representative clones (15 clones in the SY group and 11 clones in the DZ group) were sequenced. The sequence data and phylogenetic analysis of 16S rRNA gene presented that microorganism diversity of two sludge samples were abundant. Bacterial diversity presented among the outfall samples was dominated by Aeromonas sp. (5. 8%), Acidimicrobidae sp. (5. 8%) and Gemmatimonas sp. (5. 0%). In contrast, bacterial diversity presented among the control group was dominated by Xanthomonas sp. (8. 0%), Lautropia sp. (5. 8%) and Duganella sp. (5. 1%). The results indicated that due to the excessive of nitrogen and phosphorus discharged by the nitrogen fertilizer plant, the eutrophication in Dongting Lake has great influence on the microbial community structure. © 2011 Springer Science+Business Media B.V. Source

Zeng W.,Central South University | Zeng W.,Key Laboratory of Biometallurgy | Zeng W.,CSIRO | Tan S.,CSIRO | And 3 more authors.

Moderate thermophiles were used to bioleach pure chalcopyrite and showed good performance of copper extraction in the stirred tank reactor. The attached microorganisms on the mineral surface were detected by atomic force microscope (AFM). The result showed that the attached cells could produce extracellular polymeric substances (EPS) rapidly. However, it was difficult to reduce or eliminate the EPS once it was produced, and thus the large amount of EPS at the later stage of bioleaching would mediate the formation of jarosite and block the continuous copper extraction. Furthermore, the number of attached cells on the mineral surface was enumerated as a function of time and the variation was rather different from that of free cell density in the bioleaching solution. © 2010 Elsevier B.V. Source

Zeng W.,Central South University | Zeng W.,Key Laboratory of Biometallurgy | Zeng W.,CSIRO | Qiu G.,Central South University | And 2 more authors.

The electrochemistry behaviour of chalcopyrite electrodes was investigated by cyclic voltammetry. The results showed that the Cu-S intermediate species during electrochemical dissolution of chalcopyrite was mainly as Cu 2S, CuxS (1 < x < 2) and CuS. The formation process of these species was analysed. It was shown that the oxidation of chalcopyrite can only produce CuS, but CuxS and Cu2S were mainly formed due to the reduction reaction of copper ion and sulphur. Furthermore, it was found that the addition of copper ion could greatly affect the formation of Cu-S intermediate species. Therefore, during bioleaching of chalcopyrite, the effect of different concentrations of copper ion on the bioleaching process was investigated. The results revealed that when the copper concentration was low, it was hard to form Cu-S species in the ore residue. However, as copper concentration increased, the formation of Cu-S intermediate species also increased and could be detected by X-ray diffraction. © 2013 Elsevier B.V. Source

Wang Y.,Central South University | Su L.,Changsha Medical University | Zhang L.,Central South University | Zeng W.,Central South University | And 8 more authors.
Bioresource Technology

A defined mixed moderately thermophilic consortium including three terrestrial microorganisms (Leptospirillum ferriphilum, Acidithiobacillus caldus and Ferroplasma thermophilum) and a marine acidophilic halotolerant bacterium (Sulfobacillus sp. TPY) was constructed to evaluate its ability for bioleaching of chalcopyrite with the addition of sodium chloride (NaCl), and the community dynamics was monitored by real-time quantitative PCR (qPCR). It was found that Sulfobacillus sp. TPY was able to tolerate 2% (w/v) NaCl, while other three microorganisms were suppressed when the concentration of NaCl was higher than 0.35%. The results suggested that NaCl below certain concentration could improve copper extraction by using pure cultures or the consortium to bioleach chalcopyrite. Community dynamics analysis during bioleaching at 0.1% NaCl showed that Sulfobacillus sp. TPY was predominant species during the whole bioleaching process, L. ferriphilum and A. caldus were less at any time compared with Sulfobacillus sp. TPY. F. thermophilum had never been dominant species even in the final stage. © 2012 Elsevier Ltd. Source

Yang Y.,Central South University | Yang Y.,Key Laboratory of Biometallurgy | Diao M.,University of Queensland | Liu K.,Central South University | And 4 more authors.

The aim of this investigation was to compare a pure culture of Acidithiobacillus ferrooxidans GF with a mixed culture with Acidiphilium sp. DX1-1 in the bioleaching of low-grade copper ore. The leaching experiments were carried out at ambient temperature. The influence of temperature, pH, redox potential and concentration of total iron and ferric ion in solution on the performance of column bioleaching was also investigated. Total DNA was extracted from the mineral samples taken at different depths from the column top surface, and the corresponding microbial community structures were examined using amplified ribosomal DNA restriction analysis (ARDRA). Copper extractions by the pure and mixed cultures achieved 14.87% and 20.11% respectively over a period of 117 days, including 15 days of acid pre-leaching and 102 days of bioleaching. The ratios between autotrophic and heterotrophic bacteria at the top and bottom portions of the columns were 1.20:1 and 2.14:1, respectively. © 2012 Elsevier B.V. All rights reserved. Source

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