Iron-oxidizing bacteria
Useful mineral deposits of bog iron ore have formed where groundwater has historically emerged and been exposed to atmospheric oxygen.
[3] Anthropogenic hazards like landfill leachate, septic drain fields, or leakage of light petroleum fuels like gasoline are other possible sources of organic materials allowing soil microbes to de-oxygenate groundwater.
[5] The sulfurous smell of rot or decay sometimes associated with iron-oxidizing bacteria results from the enzymatic conversion of soil sulfates to volatile hydrogen sulfide as an alternative source of oxygen in anaerobic water.
To avoid this problem, they tolerate microaerophilic surface conditions or perform the photoferrotrophic Fe(II) oxidation deeper in the sediment/water column, with low light availability.
[12] However, nitrate dependent microbial Fe(II) oxidation is a light independent metabolism that has been shown to support microbial growth in various freshwater and marine sediments (paddy soil, stream, brackish lagoon, hydrothermal, deep-sea sediments) and later on demonstrated as a pronounced metabolism within the water column at the oxygen minimum zone.
[20] Therefore, the microbial community has to inhabit microaerophilic regions where the low oxygen concentration allows the cell to oxidize Fe(II) and produce energy to grow.
It was first isolated from the Kamaʻehuakanaloa Seamount (formerly Loihi) vent field, near Hawaii[18] at a depth between 1100 and 1325 meters, on the summit of this shield volcano.
[24] Large, heavily encrusted mats with a gelatinous texture are created by iron-oxidizing bacteria as a by-product (iron-oxyhydroxide precipitation), and can be present around the vent orifices.
[18] Therefore, the cell must oxidize large amounts of Fe2+ to fulfill its metabolic requirements while contributing to the mineralization process (through the excretion of twisted stalks).
[13] However, with the discovery of Fe(II) oxidation carried out under anoxic conditions in the late 1990s[16] using light as an energy source or chemolithotrophically, using a different terminal electron acceptor (mostly NO3−),[9] the suggestion arose that anoxic Fe2+ metabolism may pre-date aerobic Fe2+ oxidation and that the age of the BIF pre-dates oxygenic photosynthesis.
[7] This suggests that microbial anoxic phototrophic and anaerobic chemolithotrophic metabolism may have been present on the ancient earth, and together with Fe(III) reducers, they may have been responsible for the BIF in the Precambrian eon.
Furthermore, the temperature of the ocean has increased by almost one degree (0.74 °C) causing the melting of big quantities of glaciers contributing to the sea-level rise.
Still, at the same time, this scenario could also disrupt the cascade effect to the sediment in deep water and cause the death of benthonic animals.
Moreover it is very important to consider that iron and phosphate cycles are strictly interconnected and balanced, so that a small change in the first could have substantial consequences on the second.
[29] Iron-oxidizing bacteria can pose an issue for the management of water-supply wells, as they can produce insoluble ferric oxide, which appears as brown gelatinous slime that will stain plumbing fixtures, and clothing or utensils washed with the water carrying it.
Iron filters are similar in appearance and size to conventional water softeners but contain beds of media that have mild oxidizing power.
Wildfires may release iron-containing compounds from the soil into small wildland streams and cause a rapid but usually temporary proliferation of iron-oxidizing bacteria complete with orange coloration, gelatinous mats, and sulfurous odors.
