The ferrous iron oxidation kinetics of Thiobacillus ferrooxidans in batch cultures

• Published in: Applied microbiology and biotechnology 1999-06, Vol.51 (6), p.813-819
• Main Authors: BOON, M, RAS, C, HEIJNEN, J. J
• Format: Article
• Language: English
• Subjects: Bacteria; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Carbon dioxide; Fundamental and applied biological sciences. Psychology; Growth rate; Iron; Kinetics; Mission oriented research; Oxidation; Oxygen; Oxygen consumption; Physiology and metabolism; Thiobacillus ferrooxidans
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s002530051467

The ferrous iron oxidation kinetics of Thiobacillus ferrooxidans in batch cultures was examined, using on-line off-gas analyses to measure the oxygen and carbon dioxide consumption rates continuously. A cell suspension from continuous cultures at steady state was used as the inoculum. It was observed that a dynamic phase occurred in the initial phase of the experiment. In this phase the bacterial ferrous iron oxidation and growth were uncoupled. After about 16h the bacteria were adapted and achieved a pseudo-steady state, in which the specific growth rate and oxygen consumption rate were coupled and their relationship was described by the Pirt equation. In pseudo-steady state, the growth and oxidation kinetics were accurately described by the rate equation for competitive product inhibition. Bacterial substrate consumption is regarded as the primary process, which is described by the equation for competitive product inhibition. Subsequently the kinetic equation for the specific growth rate, μ, is derived by applying the Pirt equation for bacterial substrate consumption and growth. The maximum specific growth rate, μ^sub max^, measured in the batch culture agrees with the dilution rate at which washout occurs in continuous cultures. The maximum oxygen consumption rate, q^sub O2,max^, of the cell suspension in the batch culture was determined by respiration measurements in a biological oxygen monitor at excess ferrous iron, and showed changes of up to 20% during the course of the experiment. The kinetic constants determined in the batch culture slightly differ from those in continuous cultures, such that, at equal ferric to ferrous iron concentration ratios, biomass-specific rates are up to 1.3 times higher in continuous cultures.[PUBLICATION ABSTRACT]