5 research outputs found

    Evaluation of microbial diversity of the microbial mat from the extremely acidic Lake Robule (Bor, Serbia)

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    Extremely acidic environments are frequently formed in areas impacted by mining activities, and Lake Robule is such an ecosystem. Although an extreme environment, Lake Robule is inhabited by acidophilic microorganisms. We investigated biodiversity of the macroscopic structure known as a microbial mat formed on the lake bottom in shallow waters. Microbial mats are common in acidic environments, but their composition can differ significantly from site to site. Microbial diversity of the mat from Lake Robule was investigated using both cultivation-dependent and metagenomic approaches. The results showed the mat to be mostly inhabited by heterotrophic acidophilic bacteria. When compared to the microbial community of Lake Robule's surface water, the microbial mat proved to be a more complex community. A biogeochemical model of the mat of Lake Robule is proposed on the basis of our results and available published data

    Bioleaching of copper from samples of old flotation tailings (Copper Mine Bor, Serbia)

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    Bioleaching of samples taken from depths of 10, 15, and 20 m from old flotation tailings of the Copper Mine Bor was conducted in shaken flasks using the extremely acidic water of Lake Robule as lixiviant. The yields of copper after five weeks of the bioleaching experiments were 68.34 +/- 1.21 % for the 15-m sample, 72.57 +/- 0.57 % for the 20-m sample and 97.78 +/- 5.50 % for the 10-m sample. The obtained results were compared to the results of acid leaching of the same samples and it was concluded that bioleaching was generally more efficient for the treatment of samples taken from depths of 10 and 20 m. The content of pyrite in the 20-in sample, which contained the highest amount of this mineral, was reduced after bioleaching. The benefits of this approach are recovery of substantial amounts of copper, reducing the environmental impact of flotation tailings and the application of abundant and free water from the acidic Robule Lake as lixiviant. The obtained results showed that bioleaching could be more efficient than acid leaching for copper extraction from flotation tailings with higher sulfide contents

    Investigation of the microbial diversity of an extremely acidic, metal-rich water body (Lake Robule, Bor, Serbia)

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    An investigation of the microbial diversity in the extremely acidic, metal-rich Lake Robule was performed using culture-dependant and culture-independent (T-RFLP) methods. In addition, the ability of the indigenous bacteria from the lake water to leach copper from a mineral concentrate was tested. T-RFLP analysis revealed that the dominant bacteria in the lake water samples were the obligate heterotroph Acidiphilium cryptum (approximate to 50 % of the total bacteria) and the iron-oxidizing autotroph Leptospirillum ferrooxidans (approximate to 40 %) The iron/sulfur-oxidizing autotroph Acidithiobacillus ferrooxidans was reported to be the most abundant bacteria in the Lake in an earlier study, but it was not detected in the present study using T-RFLP, although it was isolated on solid media and detected in enrichment (bioleaching) cultures. The presence of the two bacterial species detected by T-RFLP (L. ferrooxidans and A. cryptum) was also confirmed by cultivation on solid media. The presence and relative abundance of the bacteria inhabiting Lake Robule was explained by the physiological characteristics of the bacteria and the physico-chemical characteristics of the lake water

    Cooperative Networked Systems

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    Complexity. Complex systems. Emergence: examples. Swarm intelligence. Ant colony and particle swarm optimization: applications. Stigmergy. Adaptation. Autopoiesis. Multi-agent systems. Graph representation: Laplacian. Flocking: examples from computer, communication, and control sciences. Cooperation in multi agent systems. Decentralized vs. centralized decision making. Networked systems. Cyber-physical systems. Systems of systems. Consensus based methodology applied to estimation, detection and control. Distributed sensor calibration. Distributed clock synchronization. Future directions towards convergence of computers, communications and control.11th Symposium on Neural Network Applications in Electrical Engineering (NEUREL), Proceedings, Sep 20-22, 2012, Univ Belgrade, Fac Elect Engn, Belgrade, Serbi

    Metformin Effects on Malignant Cells and Healthy PBMC; The Influence of Metformin on the Phenotype of Breast Cancer Cells

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    The aim of research was to determine the effects of maximally therapeutically achievable concentrations of metformin on malignant cells and healthy peripheral blood mononuclear cells (PBMC). Eight patients with T2D or hyperglycemia and nine healthy volunteers were included in the study. For determination of the influence of metformin on the phenotype of breast carcinoma, 1,410 patients with surgically removed tumors were included. From this group 37 breast cancer patients had DM type 2 or hyperglycemia and were pretreated with metformin alone or sometimes in combination with other antidiabetic drugs. Our results proved that metformin at low concentrations induced mild decrease in survival of malignant cells and PBMC stimulated for proliferation, but it didn't affect survival of resting PBMC. The effects of plasma of hyperglycemic patients who were under metformin therapy on autologous PBMC-induced decrease in survival of MDA-MB-361 cells, was noticeable in some patients. Metformin pretreatment for 24 h of HER2+ MDA-MB-361 cells, which were subsequently treated for 48 h with Herceptin, induced additional decline in cell survival. The analysis of influence of metformin on phenotype of breast cancer cells revealed significantly lower number of diabetic cancer patients treated with metformin with overexpressed HER2+ tumors (p lt 0.013), while the number of patients with ER+PR+ tumors was not significantly changed (p lt 0.832). In conclusion, therapeutically used concentrations of metformin exhibit mild cytotoxic action on malignant and dividing normal cells pointing to its preferred role in malignant and autoimmune diseases. The use of metformin was associated with pronounced decrease in HER2 overexpressing tumors
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