scholarly journals Gene Identification and Substrate Regulation Provide Insights into Sulfur Accumulation during Bioleaching with the Psychrotolerant Acidophile Acidithiobacillus ferrivorans

2012 ◽  
Vol 79 (3) ◽  
pp. 951-957 ◽  
Author(s):  
Maria Liljeqvist ◽  
Olena I. Rzhepishevska ◽  
Mark Dopson
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Sulfur Compound ◽  
Iron Oxidation ◽  
Sulfur Compounds ◽  
Content Type ◽  
Inorganic Sulfur ◽  
Cold Environments ◽  
Ferrous Iron Oxidation ◽  
Inorganic Sulfur Compound

ABSTRACTThe psychrotolerant acidophileAcidithiobacillus ferrivoranshas been identified from cold environments and has been shown to use ferrous iron and inorganic sulfur compounds as its energy sources. A bioinformatic evaluation presented in this study suggested thatAcidithiobacillus ferrivoransutilized a ferrous iron oxidation pathway similar to that of the related speciesAcidithiobacillus ferrooxidans. However, the inorganic sulfur oxidation pathway was less clear, since theAcidithiobacillus ferrivoransgenome contained genes from bothAcidithiobacillus ferrooxidansandAcidithiobacillus caldusencoding enzymes whose assigned functions are redundant. Transcriptional analysis revealed that thepetA1andpetB1genes (implicated in ferrous iron oxidation) were downregulated upon growth on the inorganic sulfur compound tetrathionate but were on average 10.5-fold upregulated in the presence of ferrous iron. In contrast, expression ofcyoB1(involved in inorganic sulfur compound oxidation) was decreased 6.6-fold upon growth on ferrous iron alone. Competition assays between ferrous iron and tetrathionate withAcidithiobacillus ferrivoransSS3 precultured on chalcopyrite mineral showed a preference for ferrous iron oxidation over tetrathionate oxidation. Also, pure and mixed cultures of psychrotolerant acidophiles were utilized for the bioleaching of metal sulfide minerals in stirred tank reactors at 5 and 25°C in order to investigate the fate of ferrous iron and inorganic sulfur compounds. Solid sulfur accumulated in bioleaching cultures growing on a chalcopyrite concentrate. Sulfur accumulation halted mineral solubilization, but sulfur was oxidized after metal release had ceased. The data indicated that ferrous iron was preferentially oxidized during growth on chalcopyrite, a finding with important implications for biomining in cold environments.

scholarly journals A kinetic model of ferrous iron oxidation by Acidithiobacillus ferrooxidans in a batch culture

2005 ◽  
Vol 11 (2) ◽  
pp. 59-62 ◽  
Author(s):  
Dragisa Savic ◽  
Miodrag Lazic ◽  
Vlada Veljkovic ◽  
Miroslav Vrvic
Keyword(s):  
Kinetic Model ◽  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Bubble Column ◽  
Iron Oxidation ◽  
Yield Coefficient ◽  
Transfer Rates ◽  
Ferrous Iron Oxidation ◽  
Menten Kinetic ◽  
Kinetics Of

The batch oxidation kinetics of ferrous iron by Acidithiobacillus ferrooxidans were examined at different oxygen transfer rates and pH in an aerated stirred tank and a bubble column. The microbial growth, oxygen consumption rate and ferrous and ferric iron were monitored during the biooxidation. A kinetic model was established on the basis of the Michaelis-Menten kinetic equation for bacterial growth and the constants estimated from experimental data (maximum specific growth rate 0.069 h-1, saturation constant 2.9 g/dm3, and biomass yield coefficient based on ferrous iron 0.003 gd.w./gFe). Values calculated from the model agreed well with the experimental ones regardless of the bioreactor type and pH conditions.

scholarly journals Salt Stress-Induced Loss of Iron Oxidoreduction Activities and Reacquisition of That Phenotype Depend onrusOperon Transcription inAcidithiobacillus ferridurans

2018 ◽  
Vol 84 (7) ◽  
Author(s):  
Violaine Bonnefoy ◽  
Barry M. Grail ◽  
D. Barrie Johnson
Keyword(s):  
Salt Stress ◽  
Ferrous Iron ◽  
Insertion Sequence ◽  
Transcriptional Start Site ◽  
Iron Oxidation ◽  
Content Type ◽  
Brackish Waters ◽  
Acidophilic Bacteria ◽  
Ferrous Iron Oxidation ◽  
Acidophilic Bacterium

ABSTRACTThe type strain of the mineral-oxidizing acidophilic bacteriumAcidithiobacillus ferriduranswas grown in liquid medium containing elevated concentrations of sodium chloride with hydrogen as electron donor. While it became more tolerant to chloride, after about 1 year, the salt-stressed acidophile was found to have lost its ability to oxidize iron, though not sulfur or hydrogen. Detailed molecular examination revealed that this was due to an insertion sequence, ISAfd1, which belongs to the ISPepr1subgroup of the IS4family, having been inserted downstream of the two promoters PI and PII of therusoperon (which codes for the iron oxidation pathway in this acidophile), thereby preventing its transcription. The ability to oxidize iron was regained on protracted incubation of the culture inoculated onto salt-free solid medium containing ferrous iron and incubated under hydrogen. Two revertant strains were obtained. In one, the insertion sequence ISAfd1had been excised, leaving an 11-bp signature, while in the other an ∼2,500-bp insertion sequence (belonging to the IS66family) was detected in the downstream inverted repeat of ISAfd1. The transcriptional start site of therusoperon in the second revertant strain was downstream of the two ISs, due to the creation of a new “hybrid” promoter. The loss and subsequent regaining of the ability ofA. ferriduransTto reduce ferric iron were concurrent with those observed for ferrous iron oxidation, suggesting that these two traits are closely linked in this acidophile.IMPORTANCEIron-oxidizing acidophilic bacteria have primary roles in the oxidative dissolution of sulfide minerals, a process that underpins commercial mineral-processing biotechnologies (“biomining”). Most of these prokaryotes have relatively low tolerance to chloride, which limits their activities when only saline or brackish waters are available. The study showed that it was possible to adapt a typical iron-oxidizing acidophile to grow in the presence of salt concentrations similar to those in seawater, but in so doing they lost their ability to oxidize iron, though not sulfur or hydrogen. The bacterium regained its capacity for oxidizing iron when the salt stress was removed but simultaneously reverted to tolerating lower concentrations of salt. These results suggest that the bacteria that have the main roles in biomining operations could survive but become ineffective in cases where saline or brackish waters are used for irrigation.

scholarly journals Dispersion of sulfur enables sulfur oxidation before iron oxidation in Acidithiobacillus ferrooxidans: A valuable formulation for the genetic engineering toolbox

2021 ◽  
Author(s):  
Yuta Inaba ◽  
Timothy Kernan ◽  
Alan West ◽  
Scott Banta
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Iron Reduction ◽  
Fluorescent Protein ◽  
Energy Content ◽  
Iron Oxidation ◽  
Sulfur Oxidation ◽  
Surface Hydrophobicity ◽  
Substrate Utilization Pattern ◽  
Ferrous Iron Oxidation

Acidithiobacillus ferrooxidans are acidophilic chemolithoautotrophs that are commonly reported to exhibit diauxic population growth behavior where ferrous iron is oxidized before elemental sulfur when both are available, despite the higher energy content of sulfur. We have discovered sulfur dispersion formulations that enables sulfur oxidation before ferrous iron oxidation. The oxidation of dispersed sulfur can lower the culture pH within days below the range where aerobic ferrous iron oxidation can occur so that ferric iron reduction occurs which had previously been reported over extended incubation periods with untreated sulfur. Therefore, we demonstrate that this substrate utilization pattern is strongly dependent on the cell loading in relation to sulfur concentration, sulfur surface hydrophobicity, and the pH of the culture. Our dispersed sulfur formulation, lig-sulfur, can be used to support the rapid antibiotic selection of plasmid-transformed cells, which is not possible in liquid cultures where ferrous iron is the main source of energy for these acidophiles. Furthermore, we find that media containing lig-sulfur supports higher production of green fluorescent protein (GFP) compared to media containing ferrous iron. The use of dispersed sulfur is a valuable new tool for the development of engineered A. ferrooxidans strains and it provides a new method to control iron and sulfur oxidation behaviors.

Ferrous Iron Oxidation by Salt-Tolerant “Thiobacillus prosperus”

2007 ◽  
Vol 20-21 ◽  
pp. 431-434
Author(s):  
Carol S. Davis-Belmar ◽  
James Le C. Nicolle ◽  
Paul R. Norris
Keyword(s):  
Cytochrome C ◽  
Acidithiobacillus Ferrooxidans ◽  
Oxidation Rate ◽  
Ferrous Iron ◽  
Iron Oxidation ◽  
Substrate Oxidation ◽  
Previous Description ◽  
Salt Tolerant ◽  
Ferrous Iron Oxidation ◽  
Salt Requirement

Growth on ferrous iron of a new isolate of the halotolerant acidophile “Thiobacillus prosperus” occurred with a substrate oxidation rate similar to that of Acidithiobacillus ferrooxidans, but with a requirement for salt (NaCl). These observations contrast with the previous description of “T. prosperus” in which a salt requirement was not noted and growth on ferrous iron was described as poor. As well as similar capacities for iron oxidation, these species were shown to possess similar clusters of genes (the rus operon) that encode proteins likely to be involved in transfer of electrons from ferrous iron. There were some differences in the organization of the genes and one of them that encodes a cytochrome c in At. ferrooxidans was absent from the “T. prosperus” cluster.

scholarly journals Ferrous iron oxidation and rusticyanin in halotolerant, acidophilic ‘Thiobacillus prosperus’

Microbiology ◽  
2009 ◽  
Vol 155 (4) ◽  
pp. 1302-1309 ◽  
Author(s):  
James Le C. Nicolle ◽  
Susan Simmons ◽  
Stephan Bathe ◽  
Paul R. Norris
Keyword(s):  
Electron Transport ◽  
Gene Cluster ◽  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Iron Oxidation ◽  
Subtractive Hybridization ◽  
Ferrous Iron Oxidation ◽  
In Cells

The halotolerant acidophile ‘Thiobacillus prosperus’ was shown to require chloride for growth. With ferrous iron as substrate, growth occurred at a rate similar to that of the well-studied acidophile Acidithiobacillus ferrooxidans. Previously, the salt (NaCl) requirement of ‘T. prosperus’ was not clear and its growth on ferrous iron was described as poor. A subtractive hybridization of cDNAs from ferrous-iron-grown and sulfur-grown ‘T. prosperus’ strain V6 led to identification of a cluster of genes similar to the rus operon reported to encode ferrous iron oxidation in A. ferrooxidans. However, the ‘T. prosperus’ gene cluster did not contain a homologue of cyc1, which is thought to encode a key cytochrome c in the pathway of electron transport from ferrous iron in A. ferrooxidans. Rusticyanin, another key protein in ferrous iron oxidation by A. ferrooxidans, was present in ‘T. prosperus’ at similar concentrations in cells grown on either ferrous iron or sulfur.

scholarly journals Kinetics of different bioreactor systems with Acidithiobacillus ferrooxidans for ferrous iron oxidation

2019 ◽  
Vol 128 (2) ◽  
pp. 611-627
Author(s):  
Mohsen Yavari ◽  
Sirous Ebrahimi ◽  
Valeh Aghazadeh ◽  
Mohammad Ghashghaee
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Ferrous Iron ◽  
Iron Oxidation ◽  
Fixed Bed ◽  
Lower Sensitivity ◽  
Hydraulic Residence Time ◽  
Oxidation Rates ◽  
State Process ◽  
Ferrous Iron Oxidation ◽  
Biofilm Development

Abstract The relative performance of two biofilm-based airlift reactors using different kinds of packing materials and one fixed bed biofilm reactor with a homemade packing material of high specific area (~ 1000 m2/m3) was addressed. The bioreactors operated under ferrous iron loading rates in the range of 8–120 mol Fe(II)/m3 h. Acidithiobacillus ferrooxidans cells immobilized in the three bioreactors afforded the reactions for an extended period of 120 days of continuous operation at the dilution rates of 0.2, 0.4, 0.7, 1 and 1.2 h−1. The maximum ferrous iron oxidation rates achieved in this study at a hydraulic residence time of 1.2 h were about 91, 68 and 51 mol Fe(II)/m3 h for the fixed bed, airlift1, and airlft2 bioreactors. The performance data from the fixed-bed bioreactor offered a higher potential for ferrous iron oxidation because of fast biofilm development, the formation of a thick biofilm, and lower sensitivity to shear, which enhanced the startup time of the bioreactor and the higher reactor productivity. Proper kinetic models were also presented for both the startup period and the steady-state process.

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