ATP requirements for growth and maintenance of iron-oxidizing bacteria

A simple metabolic model of ferrous oxidizing bacteria based on biochemically structured balances of ATP and NAD(P)H is proposed in order to calculate maximum yield and maintenance on ATP. Similar values of growth yield and maintenance were obtained using data of ferrous iron and/or oxygen consumption in Acidithiobacillus ferrooxidans cultures on iron under different conditions. When pyrite was the sole energy source, growth yield was higher suggesting cells could obtain energy through the sulfur compounds oxidation. Values of growth yields for Leptospirillum ferrooxidans cultures on iron were a bit lower than those obtained for A. ferrooxidans although within the experimental errors. The maintenance coefficients on ATP for both bacteria were similar and comparable to those observed in heterotrophic microorganisms. This fact is really surprising taking in account the high proton gradient that this kind of microorganisms should maintain. © 2003 Elsevier B.V. All rights reserved.