The ferrous iron oxidation kinetics of Thiobacillus ferrooxidans in continuous cultures

• Published in: Applied microbiology and biotechnology 1999-06, Vol.51 (6), p.820-826
• Main Authors: BOON, M, MEEDER, T. A, THÖNE, C, RAS, C, HEIJNEN, J. J
• Format: Article
• Language: English
• Subjects: Aquaculture; Bacteria; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Carbon dioxide; Fundamental and applied biological sciences. Psychology; Growth kinetics; Iron; Kinetics; Mission oriented research; Oxidation; Oxygen; Oxygen consumption; Physiology and metabolism; Thiobacillus ferrooxidans
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s002530051468

The oxidation and growth kinetics of ferrous iron with Thiobacillus ferrooxidans in continuous cultures was examined at several total iron concentrations. On-line off-gas analyses of O^sub 2^ and CO^sub 2^ were used to measure the oxygen and carbon dioxide consumption rates in the culture. Off-line respiration measurements in a biological oxygen monitor (BOM) were used to measure directly the maximum specific oxygen consumption rate, qO^sub 2^,max, of cells grown in continuous culture. It was shown that these reproducibly measured values of qO^sub 2^,max vary with the dilution rate. The biomass-specific oxygen consumption rate, qO^sub 2^, is dependent on the ratio of the ferric and ferrous iron concentrations in the culture. The oxidation kinetics was accurately described with a rate equation for competitive ferric iron inhibition, using the value of qO^sub 2^,max measured in the BOM. Accordingly, only the kinetic constant Ks/K^sub i^ needed to be fitted from the measurements. A new method was introduced to determine the steady-state kinetics of a cell suspension in a batch culture that only takes a few hours. The batch culture was set up by terminating the feeding of a continuous culture at its steady state. The kinetic constant K^sub s^/K^sub i^ determined in this batch culture agreed with the value determined in continuous cultures at various steady states.[PUBLICATION ABSTRACT]