Why Is Microbial Reduction of Iron Important

Some possible reasons why iron reduction by bacteria is important  

Availability of iron Iron is not very soluble, but if it is reduced to ferrous iron (which is soluble) so that the organic conpounds can stabilise iron by chelation where, later on, that iron can liberate itself from the organic matter and precipitate as iron [32,112], 

Incorporation (assimilation) of iron into proteins containing heme or iron-sulphur [40, 66,67]. 

IRB are capable of making the environment suitable for SRB. In a mixed population of micro-organisms in a biofilm, as oxygen is consumed, the redox potential starts to decrease so that nitrate, then manganic and ferric ion and the sulphate are reduced [112] this consequence can be seen in Table 4.2. 

Most of the IRB are fermentators under anaerobic conditions, however, there are a few that actually need ferric iron under anaerobic conditions [112]. To add more into the complex picture, some of the IRB can use nitrate for anaerobic respiration [112]. Little et al. reported that IRB such as Shewanella purefaciens can use oxygen, Fe(III), Mn(lV), NOj, NOj, S2O3 , SO3 and others [32]. The same researchers also reported that S. purefaciens under aerobic and anaerobic conditions may or may not use the same material (e.g., acetate that can be used aerobically but not anaerobically). Perhaps Panter is right in his recommendation that oxygen content [for IRB] is more important in determination [of their] numbers than available ferric ion content [112]. 

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