Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 411300
Title Kinetics of ferrous iron oxidation by batch and continuous cultures of thermoacidophilic Archaea at extremely low pH of 1.1–1.3
Author(s) Gonzalez-Contreras, P.A.; Weijma, J.; Buisman, C.J.N.
Source Applied Microbiology and Biotechnology 93 (2012)3. - ISSN 0175-7598 - p. 1295 - 1303.
DOI https://doi.org/10.1007/s00253-011-3460-7
Department(s) Sub-department of Environmental Technology
WIMEK
Publication type Refereed Article in a scientific journal
Publication year 2012
Keyword(s) sulfolobus-metallicus - acidianus-sulfidivorans - metallosphaera-sedula - microorganisms - concentrate - pyrite - chalcopyrite - biooxidation - acidophiles - enrichment
Abstract The extreme acid conditions required for scorodite (FeAsO4·2H2O) biomineralization (pH below 1.3) are suboptimal for growth of most thermoacidophilic Archaea. With the objective to develop a continuous process suitable for biomineral production, this research focuses on growth kinetics of thermoacidophilic Archaea at low pH conditions. Ferrous iron oxidation rates were determined in batch-cultures at pH 1.3 and a temperature of 75°C for Acidianus sulfidivorans, Metallosphaera prunea and a mixed Sulfolobus culture. Ferrous iron and CO2 in air were added as sole energy and carbon source. The highest growth rate (0.066 h-1) was found with the mixed Sulfolobus culture. Therefore, this culture was selected for further experiments. Growth was not stimulated by increase of the CO2 concentration or by addition of sulphur as an additional energy source. In a CSTR operated at the suboptimal pH of 1.1, the maximum specific growth rate of the mixed culture was 0.022 h-1, with ferrous iron oxidation rates of 1.5 g L-1 d-1. Compared to pH 1.3, growth rates were strongly reduced but the ferrous iron oxidation rate remained unaffected. Influent ferrous iron concentrations above 6 g L-1 caused instability of Fe2+ oxidation, probably due to product (Fe3+) inhibition. Ferric-containing, nano-sized precipitates of K-jarosite were found on the cell surface. Continuous cultivation stimulated the formation of an exopolysaccharide-like substance. This indicates that biofilm formation may provide a means of biomass retention. Our findings showed that stable continuous cultivation of a mixed iron-oxidizing culture is feasible at the extreme conditions required for continuous biomineral formation.
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