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Title: Comparison of iron oxidation by acidophilic bacteria
Author: Barr, David William
ISNI:       0000 0001 3446 8638
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1989
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A rang« of obligate acidophilic Iron oxidising bacteria war« compared physiologically, kinetically and biochemically. The organisms ware mesophiles, Thiobacillus ferrooxidans and Leptospirillum ferrooxldans, moderate thermophiles designated strains ALV, BC1, LH2, TH1 and TH3 and thermophlle Sulfolobus BC65. Each organism retained iron oxidizing activity in non-growing cell suspensions. Measurement was made of apparent Km and K. for ferrous Iron oxidation and its inhibition by ferric Iron in these suspensions. Values were derived from three graphical representations of the data. Values differed where identical strains had been previously reported. Evidence of a fixed relationship between Km and K1 suggested that these differences were derived from experimental variation. Ferric iron was a competitive Inhibitor of iron oxidation but copper was an uncompetitive inhibitor of L.ferrooxidans. Responses of calls to ferric Iron during growth indicated the predictive power of suspension kinetics, extremes In batch culture coinciding with the lowest and highest measured values of K. Continuous culture provided evidence of the relevance of this data to growth and explained relative cell numbers during competition in mixed mesophilic culture. These could also explain previously reported observations in mineral cultures. The production of ferric iron was controlled both by pH and process design with T.ferrooxidans. Comparable production was provided with L.ferrooxidans, utilising its ability to form macroscopic cell aggregates in sub- optimal conditions. Optimum growth conditions varied nutritionally with each strain and with particle size, ore mineralogy and carbon dioxide concentration during mineral dissolution by Sulfolobus BC63. The sulphur requirement for growth was strain dependent, quantitatively and qualitatively. Strain ALV indicated that reduced sulphur was not an obligate requirement for thermophilic iron oxidation. Iron oxidation appeared to be the controlling factor in mineral dissolution at 68°C. Iron oxidation was limited prior to maximum target metal release. Based on optical spectra each organism contained a range of (different) respiratory chain components. Both L.ferrooxidans and Sulfolobus BC65 had absorbance maxima not attributable to known cytochrome species. The peak at 578 nm for L.ferrooxidans was due to a red-pigmented, acid stable soluble protein which was reduced by ferrous Iron.
Supervisor: Not available Sponsor: Science and Engineering Research Council ; Department of Trade and Industry
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QR Microbiology