Key Laboratory of Biometallurgy

Changsha, China

Key Laboratory of Biometallurgy

Changsha, China
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Zhang M.,Central South University | Hu T.,Central South University | Ren G.,Central South University | Zhu Z.,Central South University | And 2 more authors.
Energy and Fuels | Year: 2017

The hydrophobicity of coal limits the adsorption of microorganisms and the efficiency of biological desulfurization was influenced, while the surfactant can enhance the interaction of the four phases, air, water, bacteria, and coal grain. In this experiment, three types of surfactant, anionic (SDS), cationic (DTAB), and nonionic (Tween 20), were investigated at 30 °C, and the cell concentration, pH value, leaching time, and coal biodesulfurization rate of the coal desulfurization system were detected. It is shown that the total desulfurization rate approached 29.7% in 16 days when 1100 mg/L Tween 20 was added in the shaking test, which represented the optimum efficiency. Further column leaching desulfurizating experiments showed that the desulfurization rate of the experimental group with Tween 20 (12.75%) was notably higher than that of the control group (8.32%). Along with the processing of desulfurization, the cell concentration decreased at first, and then rapidly increased, and finally stayed constant. The pH value of coal water slurry increased. The leaching time increased with the process of the desulfurization system. We concluded that the nonionic surfactant has a significant effect on coal biodesulfurization. © 2017 American Chemical Society.

Wan M.-X.,Central South University | Wan M.-X.,Johns Hopkins University | Wang R.-M.,Central South University | Xia J.-L.,Central South University | And 7 more authors.
Biotechnology and Bioengineering | Year: 2012

A novel green unicellular microalgal isolate from the freshwater of the Inner Mongolia Province of China and named as CCTCC M209220, grows between pH 6 and 11 and temperatures of 20-35°C with optimal conditions at pH 9 and 30°C. Morphological features and the phylogenetic analysis for the 18S rRNA gene reveal that the isolate is a Chlorella sorokiniana strain. A nitrogen source test reveals that this strain can grow well with nitrate and urea, but not ammonium. The strain can grow heterotrophically with glucose as the carbon source and accumulates lipid content as high as 56% (w/w) dry weight after 7 days in high glucose concentrations compared to 19% lipids achieved in 30 days of photoautotrophic culture. The relative neutral lipid content as a fraction of the total lipid is also much higher in heterotrophic culture as compared to photoautotrophic culture. © 2012 Wiley Periodicals, Inc.

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 | Year: 2012

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.

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 | Year: 2012

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.

Wang Y.,Central South University | Zeng W.,Central South University | Zeng W.,Key Laboratory of Biometallurgy | Qiu G.,Central South University | And 4 more authors.
Applied and Environmental Microbiology | Year: 2014

Three kinds of samples (acid mine drainage, coal mine wastewater, and thermal spring) derived from different sites were collected in China. Thereafter, these samples were combined and then inoculated into a basal salts solution in which different substrates (ferrous sulfate, elemental sulfur, and chalcopyrite) served as energy sources. After that, the mixed cultures growing on different substrates were pooled equally, resulting in a final mixed culture. After being adapted to gradually increasing pulp densities of chalcopyrite concentrate by serial subculturing for more than 2 years, the final culture was able to efficiently leach the chalcopyrite at a pulp density of 20% (wt/vol). At that pulp density, the culture extracted 60.4% of copper from the chalcopyrite in 25 days. The bacterial and archaeal diversities during adaptation were analyzed by denaturing gradient gel electrophoresis and constructing clone libraries of the 16S rRNA gene. The results show that the culture consisted mainly of four species, including Leptospirillum ferriphilum, Acidithiobacillus caldus, Sulfobacillus acidophilus, and Ferroplasma thermophilum, before adapting to a pulp density of 4%. However, L. ferriphilum could not be detected when the pulp density was greater than 4%. Real-time quantitative PCR was employed to monitor the microbial dynamics during bioleaching at a pulp density of 20%. The results show that A. caldus was the predominant species in the initial stage, while S. acidophilus rather than A. caldus became the predominant species in the middle stage. F. thermophilum accounted for the greatest proportion in the final stage. © 2014, american Society for Microbiology. All Rights Reserved.

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.
Hydrometallurgy | Year: 2013

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.

Zeng W.,Central South University | Zeng W.,Key Laboratory of Biometallurgy | Zeng W.,CSIRO | Tan S.,CSIRO | And 3 more authors.
Hydrometallurgy | Year: 2011

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.

Zeng W.,CSIRO | Zeng W.,Central South University | Zeng W.,Key Laboratory of Biometallurgy | Qiu G.,Central South University | And 4 more authors.
Hydrometallurgy | Year: 2011

A mixed culture of moderately thermophilic microorganisms was used to bioleach chalcopyrite at 48 °C, and it showed good performance in copper extraction. The electrochemical response of massive chalcopyrite electrodes bioleached for various periods up to 20 days was studied using cyclic voltametry. The results showed that as bioleaching progressed, the anodic and cathodic current signals decreased and the anodic peak moved gradually from low potential to high potential. Furthermore, the oxidation peak of chalcopyrite disappeared at a late stage of bioleaching, while the oxidation peak of intermediate species (CuxS (1 < × < 2)) existed throughout the whole bioleaching process. The results of SEM/EDX analysis of the electrodes indicate that at the end of bioleaching, the surface of chalcopyrite was covered with extracellular polymeric substances (EPS) and jarosite, indicating that these are the major components of a passivation layer that blocks continuous copper extraction. © 2010 Elsevier B.V. All rights reserved.

Xie J.,Central South University | Xie J.,University of Oklahoma | Xie J.,Key Laboratory of Biometallurgy | He Z.,University of Oklahoma | And 8 more authors.
Applied and Environmental Microbiology | Year: 2011

Acid mine drainage (AMD) is an extreme environment, usually with low pH and high concentrations of metals. Although the phylogenetic diversity of AMD microbial communities has been examined extensively, little is known about their functional gene diversity and metabolic potential. In this study, a comprehensive functional gene array (GeoChip 2.0) was used to analyze the functional diversity, composition, structure, and metabolic potential of AMD microbial communities from three copper mines in China. GeoChip data indicated that these microbial communities were functionally diverse as measured by the number of genes detected, gene overlapping, unique genes, and various diversity indices. Almost all key functional gene categories targeted by GeoChip 2.0 were detected in the AMD microbial communities, including carbon fixation, carbon degradation, methane generation, nitrogen fixation, nitrification, denitrification, ammonification, nitrogen reduction, sulfur metabolism, metal resistance, and organic contaminant degradation, which suggested that the functional gene diversity was higher than was previously thought. Mantel test results indicated that AMD microbial communities are shaped largely by surrounding environmental factors (e.g., S, Mg, and Cu). Functional genes (e.g., narG and norB) and several key functional processes (e.g., methane generation, ammonification, denitrification, sulfite reduction, and organic contaminant degradation) were significantly (P < 0.10) correlated with environmental variables. This study presents an overview of functional gene diversity and the structure of AMD microbial communities and also provides insights into our understanding of metabolic potential in AMD ecosystems. Copyright © 2011, American Society for Microbiology. All Rights Reserved.

Zeng W.,Central South University | Zeng W.,Key Laboratory of Biometallurgy | Zeng W.,CSIRO | Qiu G.,Central South University | And 2 more authors.
Hydrometallurgy | Year: 2013

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.

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