The Experts below are selected from a list of 1512 Experts worldwide ranked by ideXlab platform
R Nagendran - One of the best experts on this subject based on the ideXlab platform.
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fractionation behavior of heavy metals in soil during bioleaching with Acidithiobacillus thiooxidans
Journal of Hazardous Materials, 2009Co-Authors: Naresh R Kumar, R NagendranAbstract:The effects of bioleaching on the fractionation of soil heavy metals were investigated in this study. Bioleaching of heavy metals from contaminated soil was carried out in shake flask experiments. Acidophilic sulfur oxidizing bacteria Acidithiobacillus thiooxidans isolated from soil was used for bioleaching. Bioleaching resulted in removal of heavy metals at higher levels. Variations in the binding forms of heavy metals before, during and after bioleaching were evaluated. It was noticed that bioleaching affected the binding forms of all the heavy metals present in the soil. The major contaminant chromium bound mainly to the fractions of soil which are not very reactive (organic and residual fractions) also showed good removal efficiency. Bioleaching influenced the fractionation of metals in soil after treatment and most of the remnant heavy metals were bound either to residual fraction or to other not easily mobile fractions of soil. The results of this study indicated that the bioleaching process can be useful for efficient removal of heavy metals from soil. Further, the soil with remnant metals can be disposed off safely.
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changes in nutrient profile of soil subjected to bioleaching for removal of heavy metals using Acidithiobacillus thiooxidans
Journal of Hazardous Materials, 2008Co-Authors: R Nareshkumar, R NagendranAbstract:Studies were carried out to assess changes in nitrogen, phosphorus and potassium contents in soil during bioleaching of heavy metals from soil contaminated by tannery effluents. Indigenous sulfur oxidizing bacteria Acidithiobacillus thiooxidans isolated from the contaminated soil were used for bioremediation. Solubilization efficiency of chromium, cadmium, copper and zinc from soil was 88, 93, 92 and 97%, respectively. However, loss of nitrogen, phosphorus and potassium from the soil was 30, 70 and 68%, respectively. These findings indicate that despite its high potential for removal of heavy metals from contaminated soils, bioleaching results in undesirable dissolution/loss of essential plant nutrients. This aspect warrants urgent attention and detailed studies to evaluate the appropriateness of the technique for field application.
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bioleaching of heavy metals from contaminated soil using Acidithiobacillus thiooxidans effect of sulfur soil ratio
World Journal of Microbiology & Biotechnology, 2008Co-Authors: R Nareshkumar, R Nagendran, K ParvathiAbstract:Bioleaching of heavy metals from contaminated soil was carried out using indigenous sulfur oxidizing bacterium Acidithiobacillus thiooxidans. Experiments were carried out by varying sulfur/soil ratio from 0.03 to 0.33 to evaluate the optimum ratio for efficient bioleaching of heavy metals from soil. The influence of sulfur/soil ratio on the bioleaching efficiency was assessed based on decrease in pH, increase in oxidation–reduction potential, sulfate production and solubilization of heavy metals from the soil. Decrease in pH, increase in oxidation–reduction potential and sulfate production was found to be better with the increase in sulfur/soil ratio. While the final pH of the system with different sulfur/soil ratio was in the range of 4.1–0.7, oxidation reduction potential varied from 230 to 629 mV; sulfate production was in the range of 2,786–8,872 mg/l. Solubilization of chromium, zinc, copper, lead and cadmium from the contaminated soil was in the range of 11–99%. Findings of the study will help to optimize the ratio of sulfur/soil to achieve effective bioleaching of heavy metals from contaminated soils.
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Bioleaching of heavy metals from contaminated soil using Acidithiobacillus thiooxidans: effect of sulfur/soil ratio
World Journal of Microbiology & Biotechnology, 2007Co-Authors: R Nareshkumar, R Nagendran, K ParvathiAbstract:Bioleaching of heavy metals from contaminated soil was carried out using indigenous sulfur oxidizing bacterium Acidithiobacillus thiooxidans. Experiments were carried out by varying sulfur/soil ratio from 0.03 to 0.33 to evaluate the optimum ratio for efficient bioleaching of heavy metals from soil. The influence of sulfur/soil ratio on the bioleaching efficiency was assessed based on decrease in pH, increase in oxidation–reduction potential, sulfate production and solubilization of heavy metals from the soil. Decrease in pH, increase in oxidation–reduction potential and sulfate production was found to be better with the increase in sulfur/soil ratio. While the final pH of the system with different sulfur/soil ratio was in the range of 4.1–0.7, oxidation reduction potential varied from 230 to 629 mV; sulfate production was in the range of 2,786–8,872 mg/l. Solubilization of chromium, zinc, copper, lead and cadmium from the contaminated soil was in the range of 11–99%. Findings of the study will help to optimize the ratio of sulfur/soil to achieve effective bioleaching of heavy metals from contaminated soils.
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influence of initial ph on bioleaching of heavy metals from contaminated soil employing indigenous Acidithiobacillus thiooxidans
Chemosphere, 2007Co-Authors: Naresh R Kumar, R NagendranAbstract:Abstract Bioleaching of heavy metals from contaminated soil was carried out employing indigenous sulfur oxidizing bacterium Acidithiobacillus thiooxidans . Experiments were carried out to assess the influence of initial pH of the system on bioleaching of chromium, zinc, copper, lead and cadmium from metal contaminated soil. pH at the end of four weeks of bioleaching at different initial pH of 3–7 was between 0.9 and 1.3, ORP between 567 and 617 mV and sulfate production was in the range of 6090–8418 mg l −1 . Chromium, zinc, copper, lead and cadmium solubilization ranged from “59% to 98%” at different initial pH. A. thiooxidans was not affected by the increasing pH of the bioleaching system towards neutral and it was able to utilize elemental sulfur. The results of the present study are encouraging to develop the bioleaching process for decontamination of heavy metal contaminated soil.
Yili Liang - One of the best experts on this subject based on the ideXlab platform.
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responses of Acidithiobacillus thiooxidans a01 to individual and joint nickel ni2 and ferric fe3
Minerals, 2019Co-Authors: Aijia Chen, Yunhua Xiao, Yili LiangAbstract:Acidithiobacillus thiooxidans A01 is widely used in bioleaching processes and commonly thrives in most metal-rich environments. However, interactions between different heavy metals remain obscure. In this study, we elaborated the effect of ferric iron on the growth and gene expression of At. thiooxidans A01 under the stress of nickel. The results showed that 600 mM Ni2+ completely inhibited the growth and sulfur metabolism of At. thiooxidans A01. However, trace amounts of Fe3+ (0.5 mM) facilitated the growth of At. thiooxidans A01 in the presence of 600 mM Ni2+. With the addition of 5 mM Fe3+, the maximum cell density reached 1.84 × 108 cell/mL, and pH value was 0.95. In addition, metal resistance-related and sulfur metabolism genes were significantly up regulated with extra ferric iron. Taking the whole process into account, the promoting effect of Fe3+ addition can be attributed to the following: (1) alleviation of the effects of Ni2+ toxicity and restoring the growth of At. thiooxidans A01, (2) a choice of multiple pathways to export nickel ion and producing precursor of chelators of heavy metals. This can suggest that microorganisms may widely exhibit metabolic activity in iron-rich environments with heavy metals. Our study will facilitate the technique development for the processing of ore bodies with highly challenging ore compositions.
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comparative genomics of the extreme acidophile Acidithiobacillus thiooxidans reveals intraspecific divergence and niche adaptation
International Journal of Molecular Sciences, 2016Co-Authors: Xian Zhang, Yunhua Xiao, Xue Feng, Yili LiangAbstract:Acidithiobacillus thiooxidans known for its ubiquity in diverse acidic and sulfur-bearing environments worldwide was used as the research subject in this study. To explore the genomic fluidity and intraspecific diversity of Acidithiobacillus thiooxidans (A. thiooxidans) species, comparative genomics based on nine draft genomes was performed. Phylogenomic scrutiny provided first insights into the multiple groupings of these strains, suggesting that genetic diversity might be potentially correlated with their geographic distribution as well as geochemical conditions. While these strains shared a large number of common genes, they displayed differences in gene content. Functional assignment indicated that the core genome was essential for microbial basic activities such as energy acquisition and uptake of nutrients, whereas the accessory genome was thought to be involved in niche adaptation. Comprehensive analysis of their predicted central metabolism revealed that few differences were observed among these strains. Further analyses showed evidences of relevance between environmental conditions and genomic diversification. Furthermore, a diverse pool of mobile genetic elements including insertion sequences and genomic islands in all A. thiooxidans strains probably demonstrated the frequent genetic flow (such as lateral gene transfer) in the extremely acidic environments. From another perspective, these elements might endow A. thiooxidans species with capacities to withstand the chemical constraints of their natural habitats. Taken together, our findings bring some valuable data to better understand the genomic diversity and econiche adaptation within A. thiooxidans strains.
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theoretical model of the structure and the reaction mechanisms of sulfur oxygenase reductase in Acidithiobacillus thiooxidans
Advanced Materials Research, 2015Co-Authors: Xian Zhang, Yili LiangAbstract:Sulfur oxygenase reductase (SOR), which is thought to be an important enzyme involved in sulfur oxidation in many microorganisms, may play a key role in sulfur oxidation in Acidithiobacillus thiooxidans. Draft genome sequence of A. thiooxidans A01 indicated the presence of sulfur oxygenase reductase gene (sor). The complementary DNA fragment was speculated to encode a putative 311-aa full-length protein SOR. Structural analysis of SOR revealed that three cysteines located in the two conserved domains, C32 at V-G-P-K-V-C32 as well as C102 and C105 at C102-X-X-C105, might form the substrate activation and binding site. It was proposed that conserved motif H87-X3-H91-X23-E115 acted as ligands might combine with iron atom to constitute a mononuclear non-heme iron center, catalyzing the oxidation reaction of substrate.
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draft genome sequence of the extremophile Acidithiobacillus thiooxidans a01 isolated from the wastewater of a coal dump
Genome Announcements, 2014Co-Authors: Xian Zhang, Yili Liang, Yunhua XiaoAbstract:ABSTRACT The draft genome of Acidithiobacillus thiooxidans A01 contains 3,820,158 bp, with a G+C content of 53.08% and 3,660 predicted coding sequences (CDSs). The bacterium contains a series of specific genes involved in the oxidation of elemental sulfur and reduced inorganic sulfur compounds (RISCs).
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comparative study of nickel resistance of pure culture and co culture of Acidithiobacillus thiooxidans and leptospirillum ferriphilum
Archives of Microbiology, 2013Co-Authors: Ying Xu, Yili Liang, Huidan Jiang, Yunhua XiaoAbstract:The effect of Ni2+ on the growth and functional gene expression of the pure culture and co-culture of Acidithiobacillus thiooxidans and Leptospirillum ferriphilum has been studied. Compared with the pure culture, the co-culture showed a stronger sulfur and ferrous ion oxidation activity. At 100 mM, A. thiooxidans in co-culture grew faster and had 48 h shorter lag phases. The cell number of A. thiooxidans in co-culture was about 5 times higher than that in pure culture. The existence of A. thiooxidans in co-culture activated the expression of some metal resistance genes in L. ferriphilum at least 16 h in advance. A. thiooxidans in co-culture tends to chose more efficient pathways to transport nickel ion, ensuring the export of heavy metal was faster and more effective than that in pure culture. All the data indicated that there were synergetic interactions between iron- and sulfur-oxidizing bacteria under the stress of Ni2+.
Alejandro Maass - One of the best experts on this subject based on the ideXlab platform.
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a new genome of Acidithiobacillus thiooxidans provides insights into adaptation to a bioleaching environment
Research in Microbiology, 2014Co-Authors: Dante Travisany, Pilar Parada, Maria Paz Cortes, Mauricio Latorre, Alex Di Genova, Marko Budinich, Roberto A Bobadillafazzini, Mauricio Gonzalez, Alejandro MaassAbstract:Abstract Acidithiobacillus thiooxidans is a sulfur oxidizing acidophilic bacterium found in many sulfur-rich environments. It is particularly interesting due to its role in bioleaching of sulphide minerals. In this work, we report the genome sequence of At. thiooxidans Licanantay, the first strain from a copper mine to be sequenced and currently used in bioleaching industrial processes. Through comparative genomic analysis with two other At. thiooxidans non-metal mining strains (ATCC 19377 and A01) we determined that these strains share a large core genome of 2109 coding sequences and a high average nucleotide identity over 98%. Nevertheless, the presence of 841 strain-specific genes (absent in other At. thiooxidans strains) suggests a particular adaptation of Licanantay to its specific biomining environment. Among this group, we highlight genes encoding for proteins involved in heavy metal tolerance, mineral cell attachment and cysteine biosynthesis. Several of these genes were located near genetic motility genes (e.g. transposases and integrases) in genomic regions of over 10 kbp absent in the other strains, suggesting the presence of genomic islands in the Licanantay genome probably produced by horizontal gene transfer in mining environments.
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stoichiometric modeling of oxidation of reduced inorganic sulfur compounds riscs in Acidithiobacillus thiooxidans
Biotechnology and Bioengineering, 2013Co-Authors: Roberto Bobadilla A Fazzini, Maria Paz Cortes, Marko Budinich, Alejandro Maass, Leandro Padilla, Daniel MaturanaAbstract:The prokaryotic oxidation of reduced inorgan- ic sulfur compounds (RISCs) is a topic of utmost impor- tance from a biogeochemical and industrial perspective. Despite sulfur oxidizing bacterial activity is largely known, no quantitative approaches to biological RISCs oxidation have been made, gathering all the complex abiotic and enzymatic stoichiometry involved. Even though in the case of neutrophilic bacteria such as Paracoccus and Beggia- toa species the RISCs oxidation systems are well described, there is a lack of knowledge for acidophilic microorganisms. Here, we present the first experimentally validated stoichio- metric model able to assess RISCs oxidation quantitatively in Acidithiobacillus thiooxidans (strain DSM 17318), the arche- type of the sulfur oxidizing acidophilic chemolithoauto- trophs. This model was built based on literature and genomic analysis, considering a widespread mix of formerly proposed RISCs oxidation models combined and evaluated experimentally. Thiosulfate partial oxidation by the Sox system (SoxABXYZ) was placed as central step of sulfur oxidation model, along with abiotic reactions. This model was coupled with a detailed stoichiometry of biomass pro- duction, providing accurate bacterial growth predictions. In silico deletion/inactivation highlights the role of sulfur dioxygenase as the main catalyzer and a moderate function of tetrathionate hydrolase in elemental sulfur catabolism, demonstrating that this model constitutes an advanced instrument for the optimization of At. thiooxidans biomass production with potential use in biohydrometallurgical and environmental applications. Biotechnol. Bioeng. 2013;110: 2242-2251.
Yunhua Xiao - One of the best experts on this subject based on the ideXlab platform.
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responses of Acidithiobacillus thiooxidans a01 to individual and joint nickel ni2 and ferric fe3
Minerals, 2019Co-Authors: Aijia Chen, Yunhua Xiao, Yili LiangAbstract:Acidithiobacillus thiooxidans A01 is widely used in bioleaching processes and commonly thrives in most metal-rich environments. However, interactions between different heavy metals remain obscure. In this study, we elaborated the effect of ferric iron on the growth and gene expression of At. thiooxidans A01 under the stress of nickel. The results showed that 600 mM Ni2+ completely inhibited the growth and sulfur metabolism of At. thiooxidans A01. However, trace amounts of Fe3+ (0.5 mM) facilitated the growth of At. thiooxidans A01 in the presence of 600 mM Ni2+. With the addition of 5 mM Fe3+, the maximum cell density reached 1.84 × 108 cell/mL, and pH value was 0.95. In addition, metal resistance-related and sulfur metabolism genes were significantly up regulated with extra ferric iron. Taking the whole process into account, the promoting effect of Fe3+ addition can be attributed to the following: (1) alleviation of the effects of Ni2+ toxicity and restoring the growth of At. thiooxidans A01, (2) a choice of multiple pathways to export nickel ion and producing precursor of chelators of heavy metals. This can suggest that microorganisms may widely exhibit metabolic activity in iron-rich environments with heavy metals. Our study will facilitate the technique development for the processing of ore bodies with highly challenging ore compositions.
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comparative genomics of the extreme acidophile Acidithiobacillus thiooxidans reveals intraspecific divergence and niche adaptation
International Journal of Molecular Sciences, 2016Co-Authors: Xian Zhang, Yunhua Xiao, Xue Feng, Yili LiangAbstract:Acidithiobacillus thiooxidans known for its ubiquity in diverse acidic and sulfur-bearing environments worldwide was used as the research subject in this study. To explore the genomic fluidity and intraspecific diversity of Acidithiobacillus thiooxidans (A. thiooxidans) species, comparative genomics based on nine draft genomes was performed. Phylogenomic scrutiny provided first insights into the multiple groupings of these strains, suggesting that genetic diversity might be potentially correlated with their geographic distribution as well as geochemical conditions. While these strains shared a large number of common genes, they displayed differences in gene content. Functional assignment indicated that the core genome was essential for microbial basic activities such as energy acquisition and uptake of nutrients, whereas the accessory genome was thought to be involved in niche adaptation. Comprehensive analysis of their predicted central metabolism revealed that few differences were observed among these strains. Further analyses showed evidences of relevance between environmental conditions and genomic diversification. Furthermore, a diverse pool of mobile genetic elements including insertion sequences and genomic islands in all A. thiooxidans strains probably demonstrated the frequent genetic flow (such as lateral gene transfer) in the extremely acidic environments. From another perspective, these elements might endow A. thiooxidans species with capacities to withstand the chemical constraints of their natural habitats. Taken together, our findings bring some valuable data to better understand the genomic diversity and econiche adaptation within A. thiooxidans strains.
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draft genome sequence of the extremophile Acidithiobacillus thiooxidans a01 isolated from the wastewater of a coal dump
Genome Announcements, 2014Co-Authors: Xian Zhang, Yili Liang, Yunhua XiaoAbstract:ABSTRACT The draft genome of Acidithiobacillus thiooxidans A01 contains 3,820,158 bp, with a G+C content of 53.08% and 3,660 predicted coding sequences (CDSs). The bacterium contains a series of specific genes involved in the oxidation of elemental sulfur and reduced inorganic sulfur compounds (RISCs).
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comparative study of nickel resistance of pure culture and co culture of Acidithiobacillus thiooxidans and leptospirillum ferriphilum
Archives of Microbiology, 2013Co-Authors: Ying Xu, Yili Liang, Huidan Jiang, Yunhua XiaoAbstract:The effect of Ni2+ on the growth and functional gene expression of the pure culture and co-culture of Acidithiobacillus thiooxidans and Leptospirillum ferriphilum has been studied. Compared with the pure culture, the co-culture showed a stronger sulfur and ferrous ion oxidation activity. At 100 mM, A. thiooxidans in co-culture grew faster and had 48 h shorter lag phases. The cell number of A. thiooxidans in co-culture was about 5 times higher than that in pure culture. The existence of A. thiooxidans in co-culture activated the expression of some metal resistance genes in L. ferriphilum at least 16 h in advance. A. thiooxidans in co-culture tends to chose more efficient pathways to transport nickel ion, ensuring the export of heavy metal was faster and more effective than that in pure culture. All the data indicated that there were synergetic interactions between iron- and sulfur-oxidizing bacteria under the stress of Ni2+.
S. M. Mousavi - One of the best experts on this subject based on the ideXlab platform.
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environmentally friendly recovery of valuable metals from spent coin cells through two step bioleaching using Acidithiobacillus thiooxidans
Journal of Environmental Management, 2019Co-Authors: Tannaz Naseri, Nazanin Bahaloohoreh, S. M. MousaviAbstract:Abstract The technology for recycling the spent coin cells is pressing needed due to a large amount of generated spent coin cells. However, there is little information about the recycling technology of spent coin cells. In this work, a two-step bioleaching method for recovery of metals from spent coin cells by Acidithiobacillus thiooxidans is performed for the first time. In this regard, the growth characteristics of A. thiooxidans was investigated in pure culture and during the two-step bioleaching approach. The highest recovery of Li, Co and Mn was achieved at a pulp density of 30 g L−1, in values of 99%, 60%, and 20%, respectively. The structural analyzes confirmed the progress of bioleaching process. In addition, the kinetics models showed that the chemical reaction was the rate-controlling step of the two-step bioleaching of spent coin cells. The comparative results between bioleaching and chemical leaching showed that Acidithiobacillus thiooxidans can enhance the leaching of metals. Toxicity characteristic leaching procedure of the spent coin cells powder demonstrated that the bioleached residue met the environmental limitations for safe disposal. In fact, bioleaching is an effective and promising route to reduce the environmental hazard of spent coin cells.
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bacterial leaching of a spent mo co ni refinery catalyst using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans
Hydrometallurgy, 2011Co-Authors: Roya Gholami, S M Borghei, S. M. MousaviAbstract:Abstract A spent processing catalyst from an Iranian oil refinery was initially characterized physically and chemically. Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used to mobilize Al, Co, Mo and Ni from the spent catalysts under optimized conditions in batch cultures. The characteristics of the bioleach solution (pH, Eh, cell concentration and Fe(II)/Fe(III) concentration) were determined along with the concentration of metal values extracted from the catalyst. The results showed that after bioleaching using A. ferrooxidans in the presence of ferrous sulfate, maximum extractions of 63% Al, 96% Co, 84% Mo and 99% Ni were achieved after 30 days at pH 1.8–2.0. However, the highest extractions using A. thiooxidans in the presence of sulfur were 2.4% Al, 83% Co, 95% Mo and 16% Ni after 30 days at pH 3.9–4.4. The recovery of these metals decreases the environmental impact of the waste catalyst and the recycled product can be further used for industrial purposes.
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Heavy metals recovery from spent catalyst using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans
2010 International Conference on Chemistry and Chemical Engineering, 2010Co-Authors: Mohammad Reza Gholami, S M Borghei, S. M. MousaviAbstract:In this investigation, a spent processing catalyst from one of the oil refineries in Iran was initially characterized physically and chemically. Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used to mobilize aluminum, cobalt, molybdenum and nickel from hazardous spent catalysts. Bioleaching experiments were performed in batch cultures. The growth characteristics of the bacteria (pH, Eh, cell concentration and ferrous and ferric iron concentration) were determined during bioleaching along with the concentration of metal values extracted from the catalyst. The results obtained from Inductive coupled plasma-optical emission spectrometry (ICP-OES) showed that after the one-step bioleaching process using A. ferrooxidans, maximum removal efficiencies of 63%, 96%, 84% and 99% were achieved for Al, Co, Mo and Ni, respectively. However, the highest removal efficiencies using A. thiooxidans were 2.4%, 83%, 95% and 16% for Al, Co, Mo and Ni, respectively. By recovering such valuable metals, the recycled product can be further used for industrial purposes.
