The effect of dissolved cations on microbial ferrous-iron oxidation by Leptospirillum ferriphilum in continuous culture

2008 ◽  
Vol 94 (1-4) ◽  
pp. 69-76 ◽  
Author(s):  
Tunde V. Ojumu ◽  
Jochen Petersen ◽  
Geoffrey S. Hansford
Keyword(s):  
Continuous Culture ◽  
Ferrous Iron ◽  
Iron Oxidation ◽  
Leptospirillum Ferriphilum ◽  
Ferrous Iron Oxidation

The Effect of Aluminium and Magnesium Sulphate on the Rate of Ferrous Iron Oxidation by Leptospirillum ferriphilum in Continuous Culture

2007 ◽  
Vol 20-21 ◽  
pp. 156-159 ◽  
Author(s):  
Tunde Victor Ojumu ◽  
Jochen Petersen ◽  
Geoffrey S. Hansford
Keyword(s):  
Continuous Culture ◽  
Ferrous Iron ◽  
Oxidation Process ◽  
Iron Oxidation ◽  
Leach Solution ◽  
Potential Region ◽  
Leptospirillum Ferriphilum ◽  
Ferrous Iron Oxidation ◽  
Low Concentrations ◽  
Kinetics Of

In heap bioleaching the dissolution of gangue minerals from igneous ore materials can lead to the build-up of considerable concentrations of Mg and Al sulphates in the recycled leach solution. This may interfere with microbial ferrous iron oxidation, which drives the oxidation of the target minerals. The kinetics of the oxidation process have been well studied for Leptospirillum and Acidithiobacillus species in tank systems. Although not directly comparable, kinetic parameters derived for tank systems do apply also for heap bioleach conditions. In the present study the effect of solution concentrations of Mg and Al as sulphate at individual concentrations of 0 to 10 g/L and combined concentrations 0 to 16 g/L each has been investigated in continuous culture using Leptospirillum ferriphilum. Increasing the concentrations of the salts increasingly depresses the rate of ferrous iron oxidation and also shifts the viable range more and more into the low potential region. Al significantly reduces the amount of carbon maintained in the reactor (assumed to be commensurate with biomass), whereas Mg actually enhances it at low concentrations. In both cases, however, the rate is always depressed. The results indicate that heap cultures are likely to perform sub-optimally in those operations where build-up of dissolved gangue minerals is not controlled.

Kinetics of Microbial Ferrous-Iron Oxidation by Leptospirillum Ferriphilum: Effect of Ferric-Iron on Biomass Growth

2009 ◽  
Vol 71-73 ◽  
pp. 259-262 ◽  
Author(s):  
Tunde Victor Ojumu ◽  
Jochen Petersen
Keyword(s):  
Ferrous Iron ◽  
Microbial Growth ◽  
Ferric Iron ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Biomass Concentration ◽  
Reaction Conditions ◽  
Leptospirillum Ferriphilum ◽  
Ferrous Iron Oxidation ◽  
Kinetics Of

The kinetics of microbial ferrous-iron oxidation have been well studied as it is a critical sub-process in bioleaching of sulphide minerals. Exhaustive studies in continuous culture have been carried out recently, investigating the effects of conditions relevant to heap bioleaching on the microbial ferrous-iron oxidation by Leptospirillum ferriphilum [1-3]. It was postulated that ferric-iron, which is known to be inhibitory, also acts as a stress stimulus, promoting microbial growth at higher total iron concentration. This paper investigates this phenomenon further, by comparing tests run with pure ferrous-iron feeds against those where the feed is partially oxidised to ferric at comparable concentrations. The findings clearly suggest that, contrary to reactor theory, it is indeed ferrous iron concentration in the reactor feed that determines biomass concentration and that ferric iron concentration has little effect on microbial growth. Further mathematical analysis shows that the phenomenon can be explained on the basis of the Pirt equation and the particular reaction conditions employed in the test work.

Kinetics of Ferrous Iron Oxidation by Leptospirillum Ferriphilum at Moderate to High Total Iron Concentrations

2009 ◽  
Vol 71-73 ◽  
pp. 255-258 ◽  
Author(s):  
K. Penev ◽  
D. Karamanev
Keyword(s):  
Ferrous Iron ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Total Iron ◽  
Effect Of Temperature ◽  
Leptospirillum Ferriphilum ◽  
Ferrous Iron Oxidation ◽  
High Concentrations ◽  
Kinetics Of ◽  
Total Iron Concentration

The effects of temperature, pH and iron concentration on the kinetics of ferrous iron biooxidation by a free suspended culture of Leptospirillum ferriphilum were studied in shake flasks and a circulating bed bioreactor at moderate to high total iron concentration. The kinetic study showed that there are two distinct modes of iron biooxidation: growth associated and non-growth associated, depending on the pH of the medium. There were also distinctive maxima of the effect of temperature and pH on the rate of biooxidation. A kinetic model of the process was proposed, based on an electrochemical-enzymatic model. The proposed model indicates that at moderate to high concentrations (above ~12 g/L), the total iron concentration becomes the single most prominent inhibiting factor.

Kinetic Measurement of Biological Oxidation of Ferrous Iron at Low Ferric to Ferrous Ratios in a Controlled Potential Batch Reactor

2007 ◽  
Vol 20-21 ◽  
pp. 160-163
Author(s):  
Thierry Kamunga Kazadi ◽  
Jochen Petersen
Keyword(s):  
Continuous Culture ◽  
Ferrous Iron ◽  
Batch Reactor ◽  
Iron Oxidation ◽  
Redox Potentials ◽  
Monod Kinetics ◽  
Novel Device ◽  
Ferrous Iron Oxidation ◽  
Controlled Potential ◽  
Initial Work

Traditionally, the kinetics of microbial ferrous iron oxidation have been studied in continuous culture or in batch. Both methods have drawbacks: in continuous culture experiments have to be repeated at a number of dilution rates to cover the entire spectrum of ferrous to ferric ratios, which is time-consuming. Furthermore, experiments at very low ferric to ferrous ratios generally fail due to microbial wash-out at the high dilution rates needed to achieve these. In batch experiments, on the other hand, the prevalent ferric to ferrous ratio rapidly changes due to substrate depletion while the microbial population continually grows, making determination of specific momentary rates difficult. The present paper describes initial work with a novel device, the Redostat™, which allows careful electrochemical control of ferric to ferrous ratio in a batch reactor. A culture of Leptospirillum ferriphilum was grown at 35°C and 5 g/L total iron by maintaining the ferric to ferrous ratio at 0.17, 0.51 and 1.65 (corresponding to redox potentials of 419, 452 and 482 mV vs. Ag/AgCl), respectively. The correlation of data obtained from off-gas and current measurements was excellent, and fitted Monod kinetics with ferric inhibition. A hitherto unobserved effect indicates the onset of ferric iron inhibition at the low redox potentials employed here.

Ferrous iron oxidation in moderately thermophilic acidophile Sulfobacillus sibiricus N1T

2010 ◽  
Vol 56 (10) ◽  
pp. 803-808 ◽  
Author(s):  
Tatiana Y. Dinarieva ◽  
Anna E. Zhuravleva ◽  
Oksana A. Pavlenko ◽  
Iraida A. Tsaplina ◽  
Alexander I. Netrusov
Keyword(s):  
Ferrous Iron ◽  
High Performance ◽  
Iron Oxidation ◽  
Early Exponential Phase ◽  
Moderately Thermophilic ◽  
Terminal Oxidases ◽  
Cytochrome Bo ◽  
Ferrous Iron Oxidation ◽  
Transport Chain ◽  
Membrane Bound

The iron-oxidizing system of a moderately thermophilic, extremely acidophilic, gram-positive mixotroph, Sulfobacillus sibiricus N1T, was studied by spectroscopic, high-performance liquid chromatography and inhibitory analyses. Hemes B, A, and O were detected in membranes of S. sibiricus N1T. It is proposed that the electron transport chain from Fe2+ to O2 is terminated by 2 physiological oxidases: aa3-type cytochrome, which dominates in the early-exponential phase of growth, and bo3-type cytochrome, whose role in iron oxidation becomes more prominent upon growth of the culture. Both oxidases were sensitive to cyanide and azide. Cytochrome aa3 was more sensitive to cyanide and azide, with Ki values of 4.1 and 2.5 µmol·L–1, respectively, compared with Ki values for cytochrome bo3, which were 9.5 µmol·L–1 for cyanide and 7.0 µmol·L–1 for azide. This is the first evidence for the participation of a bo3-type oxidase in ferrous iron oxidation. The respiratory chain of the mixotroph contains, in addition to the 2 terminal oxidases, a membrane-bound cytochrome b573.

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