Acidithiobacillus Ferrivorans Research Articles

Processing of Alluvial Deposit Sands with a High Content of Copper and Nickel Using Combined Enrichment Technology

The aim of the present research was to examine the process of bioleaching and the application of a combined process for the recovery of copper and nickel from industrial sand deposits. The investigated sample of sands finer than 0.1 mm in size contained 0.32% Ni and 0.22% Cu. Industrial sands were processed by bioleaching in flasks on a thermostatically controlled shaker. In addition, sand roasting experiments were carried out with ammonium sulfate. An attempt was also made to use a combined process, including low-temperature roasting of the sands mixed with ammonium sulfate, water-leaching of the roasted mixture, and subsequent biological after-leaching of the residue. In the process of roasting the industrial sands in a mixture including ammonium sulfate at a temperature of 400 °C, more than 70% of the non-ferrous metals were recovered. We examined the possibility of recovering non-ferrous metals using a combined process including low-temperature roasting of industrial sands and the additional recovery of non-ferrous metals by bioleaching using the Acidithiobacillus ferrivorans bacterial strain, which was found to increase the recovery of non-ferrous metals to up to 90%.

Expression, Purification and Characterization of a Novel Rusticyanin from the Psychrotolerant Acidithiobacillus ferrivorans

Rusticyanin plays a crucial role in ferrous oxidation of sulfide minerals during bioleaching for industrial metal extraction. Diverse isoforms of rusticyanin have been found, but until now, except for type-A rusticyanin, other isoforms or sources of rusticyanin have been scarcely investigated. Here, a rusticyanin (gene locus 0470) from the psychrophilic Acidithiobacillus ferrivorans was gene-cloned, expressed, purified, and assembled in vitro. All forms of the protein exhibit extreme acid stability, even at pH 0.3. The stability of the protein is obviously enhanced after binding of the copper cofactor; the oxidation state is more stable than the reduced state. The protein has characteristic UV-vis peaks and EPR signals similar to type-A or type-B rusticyanin but is different with a small position shift and an obvious intensity change. The vibrational spectrum of the apoprotein was more different than these between the oxidation and reduced states of the protein. The ferrous oxidation kinetic rate constant of the protein is obviously faster than that of both the type-A and type-B rusticyanins previously reported. Further bioinformatics analysis reveal their changes in sequence and molecule: the mutations related to the peculiar shield belt mostly account for the variation in the properties of the protein, and the classification of the protein as a new isoform, type-C rusticyanin, is proposed.

Recovery of non-ferrous metals from sulfide ores by bioleaching on the example of the Allarechensk technogenic deposit

The possibility of processing sulfide copper-nickel raw materials by heap bioleaching due to the environmental attractiveness of this approach is becoming an increasingly relevant topic for mining and processing. On the example of the Allarechensk technogenic deposit ore, the effectiveness of the bioleaching method for the copper and nickel recovery has been considered. The content of metals in the original ore sample: nickel – 2.42 % and copper – 0.75 %. The ore grinded to the size of –5+3 mm has been irrigated with a solution containing a strain of Acidithiobacillus ferrivorans. The S : L ratio is 4 : 1, the flow rate is equal to 0.1 mL/min. In pregnant solutions, the pH and redox potential values have been controlled, and the concentrations of ferrous and ferric iron, copper, and nickel ions have also been measured. The experiment duration is 11 months, 8.9 % nickel and 6.1 % copper have been recovered. Copper has been extracted from pregnant solutions by cementation on iron, the maximum recovery is 97.3 %. Thus, it has been shown that the proposed scheme for the recovery of metals is promising for the processing of sulfide raw materials, in particular, low-grade ores and enrichment waste.

Electrotrophic perchlorate reduction by a psychrotolerant acidophile isolated from an acid rock drainage in Antarctica

A new extremophilic isolate (USS-CCA7) was obtained from an acidic environment (pH ∼ 3.2) in Antarctica phylogenetically related to Acidithiobacillus ferrivorans; its electrotrophic capacities were evaluated in a three-electrode electrochemical cell. Cyclic voltammetry showed cathodic peaks of −428 mV, −536 mV, and −634 mV (vs. Ag/AgCl; pH = 1.7; 3 M KCl) for nitrate, oxygen, and perchlorate, respectively. The catalytic role of this microorganism was also observed by a decrease in the charge transfer resistance registered via electrochemical impedance spectroscopy. Five-day chronoamperometry of culture at pH = 1.7, USS-CCA7 showed a perchlorate removal rate of 19.106 ± 1.689 mgL−1 day−1 and a cathodic efficiency of 112 ± 5.2 %. Growth on electrodes was observed by epifluorescence and scanning electron microscopy. Interestingly, the results showed that toward higher pH, the cathodic peak of perchlorate is reduced in the voltammetric profiles. This study highlights the use of this psychrotolerant acidophile for the bioremediation of harsh perchlorate-pressured terrestrial under acidic conditions.

Eurypsychrophilic acidophiles: From (meta)genomes to low-temperature biotechnologies.

Low temperature and acidic environments encompass natural milieus such as acid rock drainage in Antarctica and anthropogenic sites including drained sulfidic sediments in Scandinavia. The microorganisms inhabiting these environments include polyextremophiles that are both extreme acidophiles (defined as having an optimum growth pH < 3), and eurypsychrophiles that grow at low temperatures down to approximately 4°C but have an optimum temperature for growth above 15°C. Eurypsychrophilic acidophiles have important roles in natural biogeochemical cycling on earth and potentially on other planetary bodies and moons along with biotechnological applications in, for instance, low-temperature metal dissolution from metal sulfides. Five low-temperature acidophiles are characterized, namely, Acidithiobacillus ferriphilus, Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans, "Ferrovum myxofaciens," and Alicyclobacillus disulfidooxidans, and their characteristics are reviewed. Our understanding of characterized and environmental eurypsychrophilic acidophiles has been accelerated by the application of "omics" techniques that have aided in revealing adaptations to low pH and temperature that can be synergistic, while other adaptations are potentially antagonistic. The lack of known acidophiles that exclusively grow below 15°C may be due to the antagonistic nature of adaptations in this polyextremophile. In conclusion, this review summarizes the knowledge of eurypsychrophilic acidophiles and places the information in evolutionary, environmental, biotechnological, and exobiology perspectives.

Recovery of non-ferrous metals from sulfide ores by the method of heap bioleaching on the example of Allarechensk technogenic deposit

On the example of the Allarechensk technogenic deposit ore, the heap bioleaching method feasibility for the copper-nickel ores processing and non-ferrous metals recovery was considered. The content of metals in the initial ore sample was following: nickel – 2.42 %, copper – 0.75 %. The ore grinded to a size of -5+3 mm was irrigated with a solution containing a strain of Acidithiobacillus ferrivorans. The S:L ratio was 4:1, the flow rate was 0.1 mL/min. In pregnant solutions, the pH and ORP values were controlled, and the concentrations of ferrous and ferric iron, copper, and nickel ions were also measured. The experiment duration was 330 days, 8.9 % nickel and 6.1 % copper were recovered. The pathways for the metals extraction from pregnant solutions, as well as the utilization of bioleaching residue were considered.

Arsenopyrite Dissolution and Bioscorodite Precipitation by Acidithiobacillus ferrivorans ACH under Mesophilic Condition

Arsenopyrite is the most abundant arsenic-bearing sulfide mineral in the lithosphere, usually associated with sulfide gold ores. The recovery of this highly valuable metal is associated with the release of large quantities of soluble arsenic. One way to mitigate the effects of high concentrations of arsenic in solution is to immobilize it as scorodite precipitate, a more stable form. Hence, we addressed the scorodite formation capacity (under mesophilic conditions) of psychrotolerant Acidithiobacillus ferrivorans ACH isolated from the Chilean Altiplano. Bio-oxidation assays were performed with 1% arsenopyrite concentrate as unique energy source and produced solids were evaluated by X-ray diffraction (XRD) and QEMSCAN analysis. Interestingly, the results evidenced scorodite generation as the main sub-product after incubation for 15 days, due to the presence of the microorganism. Moreover, the QEMSCAN analysis support the XRD, detecting a 3.5% increase in scorodite generation by ACH strain and a 18.7% decrease in arsenopyrite matrix, implying an active oxidation. Finally, we presented the first record of arsenopyrite oxidation capacity and the stable scorodite production ability by a member of A. ferrivorans species under mesophilic conditions.

Non-Ferrous Metals and PGM Recovery from Low-Grade Copper–Nickel Concentrate by Bioleaching and Further Cyanidation

The aim of the present work was to perform copper, nickel, and platinum group metals (PGMs) recovery from low-grade copper–nickel concentrate containing pyrrhotite, pentlandite, and chalcopyrite by bioleaching in stirred tank reactors in batch mode and subsequent cyanidation. The concentrate contained (%) Fe 32.7, Cu 0.7, Ni 2.3, Stotal 20.9, Ssulfide 17, 0.1 g/t Pt, and 1.35 g/t Pd. The bioleaching was performed at 30 and 40 °C using two different microbial consortia. At 30 °C, bioleaching was performed using mixed culture including Acidithiobacillus ferrivorans strains isolated from the sample of acid mine drainage from copper–nickel deposit. At 40 °C, bioleaching was performed using microbial population formed during long-term bioleaching of copper-zinc concentrate at 40 °C. Bioleaching was performed for 40 days at pulp density of 10% (solid to liquid ratio 1:10). At 30 °C, 70% Ni and 14% Cu were leached, while 72% Ni and 34% Cu were recovered in the solution at 40 °C. PGM were extracted from the concentrate and bioleaching residue obtained at 40 °C by cyanidation. Cyanidation made it possible to extract 5.5% Pt and 17.3% Pd from the concentrate and 37.8% Pt and 87.8% Pd from the bioleaching residue. Thus, it was shown that the concentrate studied might be processed using bioleaching and subsequent cyanidation to extract both non-ferrous metals and PGM.

Mechanism analysis on synergistic leaching of uranium from pyrite oxidized by Acidithiobacillus ferrivorans

Mechanism analysis on synergistic leaching of uranium from pyrite oxidized by Acidithiobacillus ferrivorans

Processing of Sulfide Copper-Nickel Ores from the Deposits in Murmansk Region by Heap Leaching

The feasibility of processing low-grade copper-nickel ores by heap bioleaching was investigated. It was found that an iron-oxidizing strain of acidophilic microorganisms, Acidithiobacillus ferrivorans, is effective in the leaching of sulfide ores from the deposits in Russia’s Murmansk region. Sulfide mineralization of the studied mineral feeds was described using the methods of X-ray phase analysis and optical microscopy. In the process of leaching, the pH and Eh values and the concentrations of ferric and ferrous iron, nickel, and copper ions were monitored. By the end of the experiment, 16.5% of nickel and 7.5% of copper was recovered from the ore of the Allarechensk technogenic deposit, while 22.5% of nickel and 12.7% copper were recovered from the ore of the Nud II deposit. By silicate analysis of the solid phase, patterns of ore chemistry change were described during the process of bioleaching.

Bioleaching and Electrochemical Behavior of Chalcopyrite by a Mixed Culture at Low Temperature.

Low-temperature biohydrometallurgy is implicated in metal recovery in alpine mining areas, but bioleaching using microbial consortia at temperatures <10°C was scarcely discussed. To this end, a mixed culture was used for chalcopyrite bioleaching at 6°C. The mixed culture resulted in a higher copper leaching rate than the pure culture of Acidithiobacillus ferrivorans strain YL15. High-throughput sequencing technology showed that Acidithiobacillus spp. and Sulfobacillus spp. were the mixed culture’s major lineages. Cyclic voltammograms, potentiodynamic polarization and electrochemical impedance spectroscopy unveiled that the mixed culture enhanced the dissolution reactions, decreased the corrosion potential and increased the corrosion current, and lowered the charge transfer resistance and passivation layer impedance of the chalcopyrite electrode compared with the pure culture. This study revealed the mechanisms via which the mixed culture promoted the chalcopyrite bioleaching.

Complete Genome Sequence Analysis of Acidithiobacillus ferrivorans XJFY6S-08 Reveals Environmental Adaptation to Alpine Acid Mine Drainage.

The present work reported the complete genome sequence analysis of Acidithiobacillus ferrivorans strain XJFY6S-08 isolated from acid mine drainage in Fuyun copper mine in Xinjiang, China, revealing the potential for extreme environmental adaptation. The strain XJFY6S-08 possesses 3,161,380bp in length and 56.55% GC content. Genomic analysis revealed that this strain harbors metal-tolerant genes coding for the mer operon, arsRBC operon and a variety of metal assimilation and efflux proteins. Genes coding for K+/H+ transporting ATPase and the Na+/H+ antiporter gene nhaA for pH adaptation were identified. The presence of genes associated with various DNA repair enzymes and the synthesis of mycosporine-like amino acids precursor support the UVR resistance mechanisms. The genes related to membrane modifications (ppiBCD, slyD, surA, cfa and fabF) and resistance-nodulation-division (RND) family can play a crucial role in organic solvents tolerance. The strain XJFY6S-08 resists low-temperature conditions by a set of mechanisms such as changes of RNA metabolism, transmembrane transport, compatible solutes and transport, biofilm and EPS formation, chemotaxis and motility and ROS scavenging. These findings can provide important information for further studying the comparative genome and environmental adaptation mechanism of A. ferrivorans.

Comparative genomic analysis of two novel plasmids from Acidithiobacillus ferrivorans strain PQ33

Acidithiobacillus ferrivorans is a psychrotolerant acidophile capable of growing and oxidizing ferrous and sulphide substrates at low temperatures. To date, six genomes of this organism have been characterized; however, evidence of a plasmid in this species has been reported only once, whereby there is no conclusive role of the plasmids in the species. Herein, two novel plasmids of A. ferrivorans PQ33 were molecularly characterized and compared at a genomic scale. The genomes of two plasmids (12 kbp and 10 kbp) from A. ferrivorans PQ33 (NZ_LVZL01000000) were sequenced and annotated. The plasmids, named pAfPQ33-1 (NZ_CP021414.1) and pAfPQ33-2 (NZ_CP021415.1), presented 9 CDS and 13 CDS, respectively. In silico analysis showed proteins involved in conjugation (TraD, MobA, Eep and XerD), toxin-antitoxin systems (HicA and HicB), replication (RepA and DNA binding protein), transcription regulation (CopG), chaperone DnaJ, and a virulence gene (vapD). Furthermore, the plasmids contain sequences similar to phosphate-selective porins O and P and a diguanylate cyclase-phosphodiesterase protein. The presence of these genes suggests the possibility of horizontal transfer, a regulatory system of plasmid maintenance, and adhesion to substrates for A. ferrivorans species and PQ33. This is the first report of plasmids in this strain.

Bioleaching for the Removal of Arsenic from Mine Tailings by Psychrotolerant and Mesophilic Microbes at Markedly Continental Climate Temperatures

This study investigated the biological removal of heavy metals from mine tailings in Kazakhstan using acidophilic microorganism strains Acidithiobacillus ferrivorans 535 and Acidithiobacillus ferrooxidans 377. The experiments were conducted in shake flasks at pH 1.6, various temperatures (28 °C, 18 °C, and 8 °C), and 10% solid concentration (w/v). The results of inductively coupled plasma optical emission spectroscopy and X-ray diffraction analyses showed that arsenic was particularly efficiently removed at 28 °C. At this temperature, A. ferrooxidans 377 was more efficient at removal than the other strain. Meanwhile, A. ferrivorans 535 was more efficient than A. ferrooxidans 377 at 8 °C. One of the more significant findings to emerge from this study is that arsenic can be removed at a low temperature and high solid concentration. The results of this study support the idea that microorganisms can be used for removing arsenic via a combination of biooxidation and chemical methods.

A comparative study on psychrophilic and mesophilic biooxidation of ferrous iron by pure cultures of Acidithiobacillus ferrooxidans and Acidithiobacillus ferrivorans

Biological oxidation of ferrous sulfate by Acidithiobacillus ferrooxidans and Acidithiobacillus ferrivoransis an important process in the bioleaching of minerals and the treatment of acid mine drainage. The rate at which biooxidation reactions take place is directly related to the microorganisms’growth temperature. Decreasing the temperature of reaction causes both a decrease on the chemical reactions rates and a decrease on bacterial growth. In this study, the effects of pH and temperatures on oxidation of ferrous sulfate by a native At. ferrooxidans and At. ferrivorans strains were investigated. The biooxidation tests conducted in shake flasks at 28 °C and 8 °C and at initial pH 1.6 for 5 days. During the experiment, the mesophilic iron oxidizers were capable of growing on ferrous iron at concentrations of 4.5 g/L at low and optimum temperature. However, the rate of mesophilic biooxidation of ferrous iron was higher than that observed in the psychrophilic biooxidation. In conclusion, during the experiment the At. ferrivorans strain 535 showed high activity in oxidizing at low temperature than other strains. It means even at very low temperatures, microorganisms play an important role in the oxidation and leaching of sulphide ores.

PROKARYOTIC DIVERSTY OF ACID MINE DRAINAGE PONDS IN ORE ENRICHMENT PLANT

The biodiversity of acidophilic prokaryotes was determined in three AMD ponds (pH 2.7-6.5) in Turkey (İzmir-Halıköy antimony ore enrichment plant) using 16S rRNA cloning and denaturing gradient gel electrophoresis methods. Water samples were taken two times in March 2014 and June 2015. The microbial diversity identified includes species such as Acidiphilium angustum, Acidocella sp., Ferroplasma acidiphilum, Acidithiobacillus ferriphilus, Acidithiobacillus ferrivorans, Acidiphilium rubrum, Thiomonas sp., Acidiphilium multivorum, Acidiphilium cryptum, Ferrovum myxofaciens, Acidocella aluminiidurans with the used techniques. In addition to, it has been determined that biodiversity is variable in the operating mine pools. Aciditihobacillus ferriphilus, Acidiphilium angustum, and Acidiphilium rubrum are new records for Turkey.

Acidophilic microorganisms enhancing geochemical dynamics in an acidic drainage system, Amarillo river in La Rioja, Argentina

The Amarillo River in La Rioja, Argentina, is a natural acidic environment that is influenced by an abandoned mine. The river is characterized by extremely low pH and high concentrations of metals and metalloids. Fe(III)-bearing neoformed precipitated minerals are widespread along the hydrological basin. This work reports the presence of different species of iron-oxidizing bacteria and demonstrates that their action has a significant role in geochemical processes of the Amarillo River, mainly by catalyzing Fe2+ oxidation and intensifying the Fe(III)-bearing mineral precipitation. Various iron oxidizers (i.e. Acidithiobacillus ferrivorans, Leptospirillum ferrooxidans, Ferrimicrobium acidophilum, Alicyclobacillus cycloheptanicus) were detected in enrichment cultures at different temperatures. Moreover, this is the first report confirming that Acidithiobacillus ferrivorans is able to grow at 4 °C. Other acidophilic bacteria (i.e., Acidiphilium iwatensii) and fungi (e.g., Fodinomyces uranophilus, Coniochaeta fodinicola, Acidea extrema, Penicillium sp. and Cladosporium pseudocladosporioides) were also detected. In vitro laboratory studies recreating natural Fe(III)-bearing mineral formation showed that mineral precipitation rate was higher than 350 mg L−1 day−1 in the presence of microorganisms whereas it was about 15 mg L−1 day−1 under abiotic conditions. Jarosite was the only mineral detected in the precipitates generated by microbial action and it was also identified in the Amarillo River bed sediments. Biological Fe2+ oxidation rates depend on temperature which range from 8 to 32 mM day−1 at 4 and 30 °C, respectively. Finally, a conceptual model recognizing the significant microbial role is proposed to gain a better understanding of the biogeochemistry dynamics of the Amarillo River.

Determinants of Copper Resistance in Acidithiobacillus Ferrivorans ACH Isolated from the Chilean Altiplano.

The use of microorganisms in mining processes is a technology widely employed around the world. Leaching bacteria are characterized by having resistance mechanisms for several metals found in their acidic environments, some of which have been partially described in the Acidithiobacillus genus (mainly on ferrooxidans species). However, the response to copper has not been studied in the psychrotolerant Acidithiobacillus ferrivorans strains. Therefore, we propose to elucidate the response mechanisms of A. ferrivorans ACH to high copper concentrations (0–800 mM), describing its genetic repertoire and transcriptional regulation. Our results show that A. ferrivorans ACH can grow in up to 400 mM of copper. Moreover, we found the presence of several copper-related makers, belonging to cop and cus systems, as well as rusticyanins and periplasmatic acop protein in the genome. Interestingly, the ACH strain is the only one in which we find three copies of copB and copZ genes. Moreover, transcriptional expression showed an up-regulation response (acop, copZ, cusA, rusA, and rusB) to high copper concentrations. Finally, our results support the important role of these genes in A. ferrivorans copper stress resistance, promoting the use of the ACH strain in industrial leaching under low temperatures, which could decrease the activation times of oxidation processes and the energy costs.

Electrochemical studies on dissolution and passivation behavior of low temperature bioleaching of chalcopyrite by Acidithiobacillus ferrivorans YL15

Bioleaching has been widely applied to recover metals from sulfide minerals at medium or high temperatures, however, little is known about the bioleaching at low temperature. Electrochemical analysis techniques such as cyclic voltammetry (CV), potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS), combined with surface detection methods such as scanning electron microscopy (SEM), applied to study the electrochemical behavior of chalcopyrite during bioleaching at 6 °C. Chalcopyrite bioleaching experiments demonstrated that the maximum cell density could achieve 5.3 × 108 cells/mL. Copper extraction by Acidithiobacillus ferrivorans could reach 1.92 g/L, which is better than the 0.67 g/L of sterile experiment. CV tests found that as the leaching time passed, the anodic and cathodic current signals decreased and the anodic peak moved gradually from low potential to high potential. The increase of corrosion potential and the decrease of corrosion current in potentiodynamic polarization proved the passivation on the surface of the chalcopyrite. EIS results showed that ion exchange resistance increased from 306.1 Ω to 1913.0 Ω, which is larger than the passivation film impedance originated from elemental sulfur and polysulfide on the mineral surface. It suggested that the impedance of chalcopyrite electrode at low temperature is mainly due to ion exchange impedance but not passivation layer, which is different from the bioleaching at normal or high temperature.

Effects of elevated pressures on the activity of acidophilic bioleaching microorganisms

This study reports effects of elevated pressures on the oxidation of a soluble ferrous iron and low-grade sulphidic ore as little is known about biological iron and sulphur oxidation under these conditions. Pressure effects were studied in a pressurised batch-operated stirred tank reactor using acidophilic enrichment cultures. The oxidation of soluble Fe2+ by enrichment culture dominated by Leptospirillum ferriphilum, Sulfobacillus sp. and Ferrimicrobium acidiphilum increased with increasing pressure induced by technical air to up to +3 bar (0.63 bar PO2) and was inhibited at +7 bar (1.47 bar PO2). Elevated pressures induced by nitrogen (low oxygen partial pressure) were tolerated up to +40 bar. Another enrichment culture dominated by Acidithiobacillus ferrivorans, Sulfobacillus sp. and F. acidiphilum partially oxidised the ore at pressures up to +20 bar induced with air (4.2 bar PO2). This is the first study reporting activity of acidophiles under pressurised conditions in a stirred tank reactor.