ABSTRACT
An electrochemical investigation was conducted to evaluate the corrosion behaviour of Iron alloys such as EN-8 and 411143 in absence and in presence of microbes Acidithiobacillus ferrooxidans. Linear polarization technique was employed to measure the Polarization Resistance and corrosion rates of two different ferrous metal samples. Polarization resistance (Rp) values of EN-8 were initially higher in the presence of Acidithiobacillus ferrooxidans than the values of 411143. Growth rate of the Acidithiobacillus ferrooxidans was more and sustained longer period with EN-8 in the presence of media than in the case of alloy ‘411143’. It was observed that there was a 1.5 fold increase in corrosion rate in both the cases of EN-8 and 411143 in the presence of bacteria.High corrosion rates were recorded with the steel 41143 rather than the En-8 with respect to the optical density of the microbes. It was concluded that EN-8 was exhibited high resistance to the microbial attack.
ABSTRACT
BACKGROUND: Acidithiobacillus ferrooxidans is a facultative anaerobe that depends on ferrous ion oxidation as well as reduced sulfur oxidation to obtain energy and is widely applied in metallurgy, environmental protection, and soil remediation. With the accumulation of experimental data, metabolic mechanisms, kinetic models, and several databases have been established. However, scattered data are not conducive to understanding A. ferrooxidans that necessitates updated information informed by systems biology. RESULTS: Here, we constructed a knowledgebase of iron metabolism of A. ferrooxidans (KIMAf) system by integrating public databases and reviewing the literature, including the database of bioleaching substrates (DBS), the database of bioleaching metallic ion-related proteins (MIRP), the A. ferrooxidans bioinformation database (Af-info), and the database for dynamics model of bioleaching (DDMB). The DBS and MIRP incorporate common bioleaching substrates and metal ion-related proteins. Af-info and DDMB integrate nucleotide, gene, protein, and kinetic model information. Statistical analysis was performed to elucidate the distribution of isolated A. ferrooxidans strains, evolutionary and metabolic advances, and the development of bioleaching models. CONCLUSIONS: This comprehensive system provides researchers with a platform of available iron metabolism-related resources of A. ferrooxidans and facilitates its application.
Subject(s)
Acidithiobacillus/metabolism , Iron/metabolism , Kinetics , Knowledge BasesABSTRACT
BACKGROUND: This paper presents micro- and nano-fabrication techniques for leachable realgar using the extremophilic bacterium Acidithiobacillus ferrooxidans (A. ferrooxidans) DLC-5. RESULTS: Realgar nanoparticles of size ranging from 120 nm to 200 nm were successfully prepared using the highenergy ball mill instrument. A. ferrooxidans DLC-5 was then used to bioleach the particles. The arsenic concentration in the bioleaching system was found to be increased significantly when compared with that in the sterile control. Furthermore, in the comparison with the bioleaching of raw realgar, nanoparticles could achieve the same effect with only one fifth of the consumption. CONCLUSION: Emphasis was placed on improving the dissolvability of arsenic because of the great potential of leachable realgar drug delivery in both laboratory and industrial settings
Subject(s)
Arsenic/metabolism , Sulfides/metabolism , Acidithiobacillus/metabolism , Mining/methods , Arsenic/chemistry , Solubility , Sulfides/chemistry , Temperature , Nanotechnology , Nanoparticles/chemistry , ExtremophilesABSTRACT
Precipitation of jarosite is a very important phenomenon that is observed in the bioleaching of pyrrhotite by Acidthiobacillus ferrooxidans (A. ferrooxidans). Jarosite is a major secondary mineral formed in acid supergene environment by oxidation of metal sulphide. The formation of jarosite could decrease leached percentage. The Eh-pH diagram of FeS1.12-H2O showed that the thermodynamic parameters of the jarosite were exists steadily on Eh=360 ï½ 800, pH=2.8 ï½ 5, and the results of pH condition test is consonant with the conclusions of thermodynamic analysis. By means of XRD and SEM, it could indicate that full propagation of A. ferrooxidans in the solution is beneficial to the formation of jarosite and jarosite mediated by bacterial has a better crystalline form than that synthesized by chemical method. This study indicates that pH value and ferrous/ferric iron concentration are key factors affecting the formation of jarosite. Leached percentage is higher when frequency was set more than 2.0. It is crucial to minimize jarosite formation in order to increase factory's efficiency.
A precipitação de jarosite é um fenômeno muito importante que é observado na biolixiviação da pirrotita por Acidithiobacillus ferrooxidans (A. ferrooxidans). A jarosita é um mineral secundário principal formado no ambiente supergênico ácido pela oxidação do sulfureto do metal. A formação de jarosite pode diminuir a porcentagem de lixiviação. O diagrama de Eh-pH de FeS1.12-H2O mostrou que os parâmetros termodinâmicos da jarosite estavam firmemente presentes em Eh = 360~800, pH = 2.8~5, e os resultados do teste de condição de pH estão em consonância com as conclusões da análise termodinâmica. Por meio de XRD e SEM, pode ser indicado que a propagação completa de A. ferrooxidans na solução é benéfica para a formação de jarosite e jarosite mediada por bactérias tem uma forma cristalina melhor do que a sintetizada por método químico. Este estudo indica que o valor do pH e a concentração de ferro ferroso/férrico são fatores chave que afetam a formação de jarosite. A porcentagem de lixiviação é maior quando a freqüência foi ajustada a mais de 2,0. É crucial para minimizar a formação de jarosite, a fim de aumentar a eficiência da fábrica.
Subject(s)
Percolation , Acidithiobacillus , MineralsABSTRACT
Se llevaron a cabo procesos de biodesulfurización de dos carbones colombianos ricos en azufre ("Mina Vieja" y "Vampiro"), en reactores de lecho empacado a nivel de erlenmeyer, utilizando un consorcio de Acidithiobacillus ferrooxidans (ATCC 23270) y Acidithiobacillus thiooxidans (ATCC 15494), evaluando la adición de cisteína a la solución lixiviante. Los ensayos fueron monitoreados por medidas de hierro en solución, pH y potencial redox. Adicionalmente, se hicieron análisis mineralógicos por difracción de rayos X (DRX) antes y después de los experimentos. Los ensayos sin adición de cisteína alcanzaron una oxidación de pirita de 45.3% y 57.9% para "Mina Vieja" y "Vampiro" respectivamente. Cuando se adicionó cisteína, la oxidación aumentó en 14.9% para "Mina Vieja" y 6.4% para "Vampiro". Por otra parte, todos los ensayos evidenciaron remoción de caolinita, debido a su interacción con el ácido sulfúrico del medio. Con base en los resultados obtenidos, los componentes del carbón influenciaron tanto crecimiento bacteriano como la eficiencia de la cisteína sobre el grado de pirita oxidada.
Biodesulphurization processes of a two sulphur-rich coals from Colombia ("Mina Vieja" y "Vampiro") were carried out at packed-bed reactors at erlenmeyer level, using a consortium of Acidithiobacillus ferrooxidans (ATCC 23270) and Acidithiobacillus thiooxidans (ATCC 15494). Cysteine addition were evaluated. The assays were monitored by measurements of iron content, pH, and redox potential. X-ray diffraction (XRD) were used to establish the mineralogy before and after the process. The assays without cysteine respectively reached a pyrite oxidation of 45.3% ("Mina Vieja") and 57.9% ("Vampiro") after 38 days. Cysteine addition improved pyrite oxidation by 14.9% ("Mina Vieja") and 6.4% ("Vampiro"). On the other hand, all the assays removed kaolinite by interaction with sulphuric acid of the media. In base to the results, coal compounds influence bacterial growth and affects the efficiency of cysteine over pyrite oxidation.
ABSTRACT
The mining industry is looking forward for bacterial consortia for economic extraction of copper from low-grade ores. The main objective was to determine an optimal bacterial consortium from several bacterial strains to obtain copper from the leach of chalcopyrite. The major native bacterial species involved in the bioleaching of sulphide ore (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans and Leptospirillum ferriphilum) were isolated and the assays were performed with individual bacteria and in combination with At. thiooxidans. In conclusion, it was found that the consortium integrated by At. ferrooxidans and At. thiooxidans removed 70% of copper in 35 days from the selected ore, showing significant differences with the other consortia, which removed only 35% of copper in 35 days. To validate the assays was done an escalation in columns, where the bacterial consortium achieved a higher percentage of copper extraction regarding to control.
Subject(s)
Bacteria/metabolism , Copper/metabolism , Industrial Microbiology/methods , Microbial ConsortiaABSTRACT
En este estudio se evaluó la adaptación de una cepa compatible con Acidithiobacillus ferrooxidans a altas densidades de pulpa de calcopirita, esfalerita y galena, con dos distribuciones de tamaño de partícula, -200 y -325 serie Tyler de tamices. Los microorganismos fueron adaptados por la disminución gradual de la fuente principal de energía, sulfato ferroso, y el aumento en el contenido de mineral, para finalmente realizar un subcultivo sin la adición de fuente de energía externa. La realización de subcultivos en serie resultó ser una estrategia eficaz para la adaptación a altas densidades de pulpa de esfalerita, calcopirita y galena indicando que el protocolo empleado es adecuado. Los resultados muestran que la cepa compatible con Acidithiobacillus ferrooxidans es más resistente a altas concentraciones de esfalerita, seguido por calcopirita y finalmente por galena. El tamaño de partícula juega un papel fundamental en la adaptación de los microorganismos al mineral.
In this study the adaptation of Acidithiobacillus ferrooxidans-like to high concentrations of chalcopyrite, sphalerite and galena were evaluated with two mineral-particle sizes: 200 and 325 Tyler mesh. The strain was adapted using two simultaneous processes. The first one consisted in a gradual decreasing of the main energy source, ferrous sulphate. The second one consisted in a gradual increasing of the mineral content. Finally, a test was made without ferrous sulphate. The serial subculturing was found to be an efficient strategy to adapt Acidithiobacillus ferrooxidans-like to higher concentrations of chalcopyrite, sphalerite and galena. This indicates that a suitable protocol was employed. The results showed that Acidithiobacillus ferrooxidans-like is more resistant to high concentration of sphalerite, chalcopyrite and galena in descendant order. The particle size played an important role in the adaption of microorganism to the mineral.
Subject(s)
Adaptation, Biological/physiology , Adaptation, Biological/genetics , Adaptation, Biological/immunologyABSTRACT
With reverse transcriptase PCR, the transcripton of copper homeostasis relative gene Afe0329 in Acidithiobacillus ferrooxians standard strain ATCC23270 was investigated. The further analysis of genes in this transcripton was analyzed employed by Vector NTI, Blast, TMHMM Server, PSORTb software and so on. From the DNA of different strains, the transcripton of Afe0329 was amplified using special primer pairs to identify the universality of it in the genome of A.ferrooxidans strains. The results showed that gene Afe0330 and Afe0331 were cotranscribed with Afe0329, and they were in a single transcripton. Gene Afe0329 was supported to express a P1b3-type ATPase which is a heavy metal ion pumping transmembrane protein, protein AFE0330 which expressed by gene Afe0330 was a cytoplasmic protein, no significant ho- mologous sequences of Afe0330 or Afe0331 had been obtained by Blast analysis. And the transcripton of Afe0329 was universal in genome of A. ferrooxidans strains.
ABSTRACT
Reverse transcriptase-PCR experiments suggest that the two clusters of genes potentially involved in the oxidation of reduced sulfur compounds are organized as operons in strain of the acidophilic, chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans ATCC 23270, the two clusters of genes including such the ORF of putative sulfate-thiosulfate-molybdate binding proteins, the ORF of putative thiosulfate: quinone oxidoreductase and the ORF of the rhodanese-like protein (P21). Bioinformatic analyses have predicted the possible promoters sequences and the possible +1 start site of transcription for the doxDA operons.
ABSTRACT
Covellite oxidation was evaluated with two acidophilic thiobacilli that are important in bioleaching processes.The experiments were carried out in shake flasks in the absence and presence of 4 g/L Fe2+ (as ferrous sulphate) at pH 2.0, 150 rpm and 35 ℃. The tests showed that the copper extraction by the Acidithiobacillus ferrooxidans culture was nearly the same as that by the mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus caldus. On the other hand, additional iron clearly improved Cu leaching.
ABSTRACT
Covellite oxidation was evaluated with two acidophilic thiobacilli that are important in bioleaching processes.The experiments were carried out in shake flasks in the absence and presence of 4 g/L Fe2+ (as ferrous sulphate) at pH 2.0, 150 rpm and 35 ℃. The tests showed that the copper extraction by the Acidithiobacillus ferrooxidans culture was nearly the same as that by the mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus caldus. On the other hand, additional iron clearly improved Cu leaching.
ABSTRACT
Covellite oxidation was evaluated with two acidophilic thiobacilli that are important in bioleaching processes.The experiments were carried out in shake flasks in the absence and presence of 4 g/L Fe2+ (as ferrous sulphate) at pH 2.0, 150 rpm and 35 ℃. The tests showed that the copper extraction by the Acidithiobacillus ferrooxidans culture was nearly the same as that by the mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus caldus. On the other hand, additional iron clearly improved Cu leaching.
ABSTRACT
Acidithiobacillus ferrooxidans are able to synthesize intra-cellular electron-dense magnetite,which makes possible that the bio-nano-magnetic particles could be obtained by cultivating Acidithiobacillus ferrooxidans. In order to isolate the strain which has the capacity to produce more magnetic particles, the solid-plate magnetophoresis method was firstly created. After isolation using the method, the rate of the cells which contain intra-cellular magnetic particles was increased from 30% to more than 90%, in addition, after isolation each cell possessed 2~5 magnetic particles which disperse in cells. The isolated cells are able to orient and migrate to the magnet in artificial magnetic field but could not orient swimming only under the geomagnetic field. Magnetosomes produced by Acidithiobacillus ferrooxidans were range from 40nm to 90 nm according to the results of TEM. Energy dispersive X-ray analysis indicated that extracted magnetic particles consisted of oxygen and iron. The results show that some Acidithiobacillus ferrooxidans cells have weak magnetotaxis and they could be able to be separated by solid-plate magnetophoresis method from others. With the development of this new isolation method, it is possible to do deeper research to generate a comprehensive description of the mechanism that how Acidithiobacillus ferrooxidans synthesize the magnetic particles.