Iron oxidation, thiobacilli

Ecological and cultural studies of iron-oxidizing bacteria have identified a number of unusual abilities of the bacterium. Thiobacilli are able to tolerate high concentrations (up to 10 g 1 ) of Zn, Cu, Co, ... 

An ATP-dependent reduction of pyridine nucleotides (NADH, NADPH) provides the organism with reducing power for CO2 assimilation. In the iron-oxidizing bacteria, this aspect of metabolism has received little attention however, in other thiobacilli, reduction of pyridine nucleotides has been investigated (Aleem, 1970). Since the redox potentials of NAD /NADH and NADP /NADPH are low (Eq = —0.320 and —0.324 V, respectively), and... 

Less well known is the phenomenon of corrosion of metals by thiobacilli such as sulfur-oxidizing bacteria (SOB) and iron-oxidizing bacteria (lOB) which can proliferate in symbiosis with SRB and MPB particularly in acid sulfate soils such as Neogene strata and reclaimed lands with very low pH values. Essentially, the process requires an inor-... 

It is useful to note that it is necessary to have oxygen and reduced sulfur for Thiobacilli to act on and produce sulfuric acid. The growth of anaerobic sulfate-reducing bacteria in sewage produces H2S, which migrates to the air space at the top of the line, where it is oxidized to sulfuric acid in the water droplets at the crown of the pipe by Thiobacilli. The corrosion problem is because of the dissolution of alkaline mortar by the sulfuric acid produced by the bacterial action, followed by the corrosion of the ductile iron in the sewage pipe (50). 

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