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| Titel: |
Bacterial reduction of ferric iron and co-respiration of O2 and Fe3+ at various oxygen concentrations |
| Auteur: |
Daniel Kupka |
| Verschenen in: |
Acta Montanistica Slovaka |
| Paginering: | Jaargang 10 (2005) nr. speci 1 pagina's 178-185 |
| Jaar: |
2005 |
| Inhoud: |
Acidiphilium SJH, was cultivated in laboratory bioreactor under aerobic, micro-aerobic and anaerobic conditions. The bacterium oxidized organic substratum D-galactose to carbon dioxide using oxygen and ferric iron as terminal electron acceptor. The reduction of ferric iron to ferrous iron was observed in either fully aerobic or anoxic conditions. Bacterial growth measured as turbidity and the substrate oxidation measured as CO2 production showed an exponential pattern. The maximum specific growth rate μ = 0,12 h-1 (generation time of 5.8 h) was observed under aerobic conditions. The molar ratio of CO2 produced to O2 consumed CO2/O2 of approx. 1.16 in fully aerobic conditions indicate bacterial preference of oxygen as electron acceptor though weak reduction of ferric iron by the bacterial culture was apparent. Under conditions with the oxygen limitation, the molar CO2/O2 ratio increased to above 4 with a marked prevalence of Fe3+ as the electron acceptor. The co-respiration of both oxygen and ferric iron regardless of the concentration of soluble oxygen suggests a constitutive synthesis of the “iron-reductase” enzyme system in this bacterium. On the other hand, the bacterial growth was inhibited in cultures sparged with a pure nitrogen gas. The organic substrate oxidation and ferric iron reduction by apparently non-growing bacteria was linear and extremely slow for a few days. The recovery and acceleration of bacterial growth and ferric iron reduction was observed after changing the inconvenient incubation in pure N2 atmosphere into incubation allowing the CO2 accumulation within the medium in a closed reactor. Reduction of ferric iron to ferrous iron in micro-aerobic conditions proceeded most rapidly and completely. The change in the Fe3+/Fe2+ ratio caused decrease of the oxidation-reduction potential of the medium (Eh) from approx. 800 mV to approx.350 mV with respect to the Nernst’s equation. |
| Uitgever: |
Technical University of Kosice, the Faculty of Mining, Ecology, Process Control and Geotechnologies (F BERG) |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 2 van 13 gevonden artikelen
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