Bacterial Removal of Iron from Bauxite Ores: A Comparative Study Using Three Dissimilatory Iron Reducing Microorganisms

2009 ◽  
Vol 71-73 ◽  
pp. 505-508 ◽  
Author(s):  
N. Papassiopi ◽  
K. Vaxevanidou ◽  
A. Kontogianni
Keyword(s):  
Comparative Study ◽  
Ferrous Iron ◽  
Bacterial Species ◽  
Shewanella Putrefaciens ◽  
Iron Removal ◽  
Reductive Dissolution ◽  
Strict Anaerobe ◽  
Reducing Ability ◽  
Bacterial Removal ◽  
Common Technique

Bio-beneficiation of ores through iron removal is a common technique, but not yet tested for the case of bauxite. In this study we compared the iron reducing ability of three bacterial species with and without the chelating action of EDTA. Tests were carried out using a diasporic bauxite sample containing 19.3% Fe2Ο3 in the form of hematite, goethite and chamosite. Reductive dissolution was attempted using three neutrophilic, dissimilatory Fe(III) respirators, i.e. the facultative anaerobes Shewanella putrefaciens and Ferrimonas balearica and the strict anaerobe Desulfuromonas palmitatis. Almost 25% of Fe was reduced by D. palmitatis and S. putrefaciens and 30% by F. balearica in bauxite samples. In the case of S. putrefaciens and F. balearica, Fe(III) reduction took place without addition of EDTA, but most of the biologically produced Fe(II) reprecipitated. The addition of EDTA proved to hinder the bioreduction potential for both S. putrefaciens and F. balearica. On the contrary, D. palmitatis was able to reduce Fe(III) oxides only in the presence of EDTA. Moreover, the presence of EDTA helped maintain biogenic ferrous iron in solution.

scholarly journals Biosorption of Cr(VI) by three different bacterial species supported on granular activated carbon—A comparative study

2008 ◽  
Vol 153 (1-2) ◽  
pp. 799-809 ◽  
Author(s):  
C. Quintelas ◽  
B. Fernandes ◽  
J. Castro ◽  
H. Figueiredo ◽  
T. Tavares
Keyword(s):  
Activated Carbon ◽  
Comparative Study ◽  
Bacterial Species ◽  
Granular Activated Carbon

Inhibition of Biological Reductive Dissolution of Hematite by Ferrous Iron

2004 ◽  
Vol 38 (1) ◽  
pp. 187-193 ◽  
Author(s):  
Richard A. Royer ◽  
Brian A. Dempsey ◽  
Byong-Hun Jeon ◽  
William D. Burgos
Keyword(s):  
Ferrous Iron ◽  
Reductive Dissolution

scholarly journals A Comparative Study of Iron Removal Efficiency by Precipitation Method and Deferrization Unit of DAN DADJI-Illéla Drilling

2020 ◽  
Vol 36 (1) ◽  
pp. 54-62
Author(s):  
Yahouza Zaneidou ◽  
Manzola Abdou Salam ◽  
Amadou Haoua ◽  
Laouali Mahaman Sani
Keyword(s):  
Comparative Study ◽  
Removal Efficiency ◽  
Iron Removal ◽  
Precipitation Method

An experimental study on iron removal with ferric sludge recycling

2000 ◽  
Vol 42 (1-2) ◽  
pp. 393-397 ◽  
Author(s):  
N. Tufekci ◽  
H.Z. Sarikaya ◽  
I. Ozturk
Keyword(s):  
Reaction Kinetics ◽  
Ferrous Iron ◽  
Natural Waters ◽  
Ferric Iron ◽  
Ferric Hydroxide ◽  
Iron Removal ◽  
Aeration Tank ◽  
Batch Reactors ◽  
High Concentration ◽  
Activated Sludge Processes

An iron removal process, which makes use of the catalytic effect of ferric iron, is proposed. For this purpose, the reaction kinetics derived from the data of the batch experiments was applied to the continuous flow system. Based upon this reaction kinetics, it has been theoretically demonstrated that the volumes of aeration tanks can be significantly reduced by keeping a high concentration of ferric iron in the reactor. However, in natural waters, Fe(II) is found commonly to be in the range of 0.01–10 mg/l. These ferrous iron concentrations are not high enough to maintain the high concentrations of ferric iron in the aeration tank. Therefore, similar to the activated sludge processes used in wastewater treatment, it is suggested that the required Fe(III) concentrations can be maintained by recycling Fe(OH)3 sludge back to the aeration tank. It is known that the oxygenation of ferrous iron is catalyzed by the reaction product, ferric hydroxide. Catalytic action of the ferric iron sludges on the oxidation of ferrous iron by aeration has been identified and the kinetics of this catalytic reaction has been formulated by the authors. The oxidation of Fe(II) was studied in batch reactors in which the concentration of Fe(III) was in the range of 0–600 mg/l. The oxygenation rate increased linearly with the increasing Fe(III) concentrations up to 50 mg/l and a second-order polynomial relationship was found between the reaction rate and the Fe(III) concentrations in the range of 50–600 mg/l. The required volume (V) of the aeration tank and the effluent Fe(II) concentrations were determined as a function of the Fe(III) concentration. The volume of the aeration tank required for the same Fe(II) conversion was reduced by a factor of 15 when the Fe(III) concentration was raised from 0 to 600 mg/l at pH=6.7. No incremental benefit of the increase of Fe(III) concentration was observed at Fe(III) levels beyond the 600 mg/l. This study has experimentally demonstrated that significant savings can be achieved in iron removal systems by recirculating the Fe(III) sludges back to the aeration tank.

Ferrous iron removal by limestone and crushed concrete in dynamic flow columns

2013 ◽  
Vol 124 ◽  
pp. 165-171 ◽  
Author(s):  
Yu Wang ◽  
Saraya Sikora ◽  
Timothy G. Townsend
Keyword(s):  
Ferrous Iron ◽  
Iron Removal ◽  
Dynamic Flow ◽  
Crushed Concrete

scholarly journals Antibiotic Resistance Gene Diversity and Virulence Gene Diversity Are Correlated in Human Gut and Environmental Microbiomes

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Pedro Escudeiro ◽  
Joël Pothier ◽  
Francisco Dionisio ◽  
Teresa Nogueira
Keyword(s):  
Antibiotic Resistance ◽  
Comparative Study ◽  
Microbial Communities ◽  
Pathogenic Bacteria ◽  
Gene Diversity ◽  
Bacterial Species ◽  
Human Populations ◽  
Virulence Determinants ◽  
Human Gut ◽  
The World

ABSTRACT Human beings have used large amounts of antibiotics, not only in medical contexts but also, for example, as growth factors in agriculture and livestock, resulting in the contamination of the environment. Even when pathogenic bacteria are the targets of antibiotics, hundreds of nonpathogenic bacterial species are affected as well. Therefore, both pathogenic and nonpathogenic bacteria have gradually become resistant to antibiotics. We tested whether there is still cooccurrence of resistance and virulence determinants. We performed a comparative study of environmental and human gut metagenomes from different individuals and from distinct human populations across the world. We found a great diversity of antibiotic resistance determinants (AR diversity [ARd]) and virulence factors (VF diversity [VFd]) in metagenomes. Importantly there is a correlation between ARd and VFd, even after correcting for protein family richness. In the human gut, there are less ARd and VFd than in more diversified environments, and yet correlations between the ARd and VFd are stronger. They can vary from very high in Malawi, where antibiotic consumption is unattended, to nonexistent in the uncontacted Amerindian population. We conclude that there is cooccurrence of resistance and virulence determinants in human gut microbiomes, suggesting a possible coselective mechanism. IMPORTANCE Every year, thousands of tons of antibiotics are used, not only in human and animal health but also as growth promoters in livestock. Consequently, during the last 75 years, antibiotic-resistant bacterial strains have been selected in human and environmental microbial communities. This implies that, even when pathogenic bacteria are the targets of antibiotics, hundreds of nonpathogenic bacterial species are also affected. Here, we performed a comparative study of environmental and human gut microbial communities issuing from different individuals and from distinct human populations across the world. We found that antibiotic resistance and pathogenicity are correlated and speculate that, by selecting for resistant bacteria, we may be selecting for more virulent strains as a side effect of antimicrobial therapy.

scholarly journals FlrA Represses Transcription of the Biofilm-Associated bpfA Operon in Shewanella putrefaciens

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Yuan-Yuan Cheng ◽  
Chao Wu ◽  
Jia-Yi Wu ◽  
Hui-Ling Jia ◽  
Ming-Yu Wang ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Promoter Region ◽  
Bacterial Species ◽  
Shewanella Putrefaciens ◽  
Common Mechanism ◽  
Diguanylate Cyclase ◽  
Aerobic Growth ◽  
Content Type ◽  
Transcription Regulator ◽  
Strict Regulation

ABSTRACT Manipulation of biofilm formation in Shewanella is beneficial for application to industrial and environmental biotechnology. BpfA is an adhesin largely responsible for biofilm formation in many Shewanella species. However, the mechanism underlying BpfA production and the resulting biofilm remains vaguely understood. We previously described the finding that BpfA expression is enhanced by DosD, an oxygen-stimulated diguanylate cyclase, under aerobic growth. In the present work, we identify FlrA as a critical transcription regulator of the bpfA operon in Shewanella putrefaciens CN32 by transposon mutagenesis. FlrA acted as a repressor of the operon promoter by binding to two boxes overlapping the −10 and −35 sites recognized by σ70. DosD regulation of the expression of the bpfA operon was mediated by FlrA, and cyclic diguanylic acid (c-di-GMP) abolished FlrA binding to the operon promoter. We also demonstrate that FlhG, an accessory protein for flagellum synthesis, antagonized FlrA repression of the expression of the bpfA operon. Collectively, this work demonstrates that FlrA acts as a central mediator in the signaling pathway from c-di-GMP to BpfA-associated biofilm formation in S. putrefaciens CN32. IMPORTANCE Motility and biofilm are mutually exclusive lifestyles, shifts between which are under the strict regulation of bacteria attempting to adapt to the fluctuation of diverse environmental conditions. The FlrA protein in many bacteria is known to control motility as a master regulator of flagellum synthesis. This work elucidates its effect on biofilm formation by controlling the expression of the adhesin BpfA in S. putrefaciens CN32 in response to c-di-GMP. Therefore, FlrA plays a dual role in controlling motility and biofilm formation in S. putrefaciens CN32. The cooccurrence of flrA, bpfA, and the FlrA box in the promoter region of the bpfA operon in diverse Shewanella strains suggests that bpfA is a common mechanism that controls biofilm formation in this bacterial species.

scholarly journals Ferrous Iron Removal Promotes Microbial Reduction of Crystalline Iron(III) Oxides

1999 ◽  
Vol 33 (14) ◽  
pp. 2492-2492 ◽  
Author(s):  
Eric E. Roden ◽  
Matilde M. Urrutia
Keyword(s):  
Ferrous Iron ◽  
Microbial Reduction ◽  
Iron Removal
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