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The class '''Zetaproteobacteria''' is the sixth and most recently described class of the [[Proteobacteria]].<ref name="Emerson2007">{{cite doi|10.1371/journal.pone.0000667}}</ref> Zetaproteobacteria can also refer to the group of organisms assigned to this class. The Zetaproteobacteria are represented by a single described species, ''[[Mariprofundus ferrooxydans]]'',<ref>{{lpsn|m/mariprofundus.html|mariprofundus}}</ref> which is an [[Microbial_metabolism#Ferrous_iron_.28Fe2.2B.29_oxidation|iron-oxidizing]] [[neutrophile|neutrophilic]] [[chemolithotrophic|chemolithoautotroph]] originally isolated from [[Lōʻihi Seamount|Loihi Seamount]] in 1996 (post-eruption).<ref name="Emerson2007" /><ref name="Emerson2002">{{cite pmid|12039770}}</ref> [[Molecular cloning]] techniques focusing on the [[Ribosomal RNA|small subunit ribosomal RNA gene]] have also been used to identify a more diverse majority of the Zetaproteobacteria that have as yet been unculturable.<ref name="McAllister2011">{{cite doi|10.1128/AEM.00533-11}}</ref>
The class '''Zetaproteobacteria''' is the sixth and most recently described class of the [[Proteobacteria]].<ref name="Emerson2007">{{cite doi|10.1371/journal.pone.0000667}}</ref> Zetaproteobacteria can also refer to the group of organisms assigned to this class. The Zetaproteobacteria are represented by a single described species, ''[[Mariprofundus ferrooxydans]]'',<ref>{{lpsn|m/mariprofundus.html|mariprofundus}}</ref> which is an [[Microbial_metabolism#Ferrous_iron_.28Fe2.2B.29_oxidation|iron-oxidizing]] [[neutrophile|neutrophilic]] [[chemolithotrophic|chemolithoautotroph]] originally isolated from [[Lōʻihi Seamount|Loihi Seamount]] in 1996 (post-eruption).<ref name="Emerson2007" /><ref name="Emerson2002">{{cite pmid|12039770}}</ref> [[Molecular cloning]] techniques focusing on the [[Ribosomal RNA|small subunit ribosomal RNA gene]] have also been used to identify a more diverse majority of the Zetaproteobacteria that have as yet been unculturable.<ref name="McAllister2011">{{cite doi|10.1128/AEM.00533-11}}</ref>


Regardless of culturing status, the Zetaproteobacteria show up worldwide in [[estuary|estuarine]] and marine habitats associated with opposing steep [[redox gradient]]s of reduced ([[ferrous]]) iron and oxygen, either as a minor detectable component or as the dominant member of the microbial community.<ref name="Schauer2011">{{cite doi|10.1111/j.1462-2920.2011.02530.x}}</ref><ref name="HodgesOlson2009">{{cite doi|10.1128/AEM.01835-08}}</ref><ref name="DavisCleft">{{cite doi|10.1080/01490450902889080}}</ref><ref name="Forget2010">{{cite doi|10.1111/j.1472-4669.2010.00247.x}}</ref><ref name="Handley2010">{{cite doi|10.1038/ismej.2010.38}}</ref><ref name="Kato2009fluid">{{cite doi|10.1111/j.1462-2920.2009.02031.x}}</ref> Zetaproteobacteria have been most commonly found at deep-sea [[hydrothermal vents]],<ref name="McAllister2011" /> though recent discovery of members of this class in near-shore environments has led to the reevaluation of Zetaproteobacteria distribution and significance.<ref name="McBeth2011">{{cite doi|10.1128/AEM.02095-10}}</ref>
Regardless of culturing status, the Zetaproteobacteria show up worldwide in [[estuary|estuarine]] and marine habitats associated with opposing steep [[redox gradient]]s of reduced ([[ferrous]]) iron and oxygen, either as a minor detectable component or as the dominant member of the microbial community.<ref name="Schauer2011">{{cite doi|10.1111/j.1462-2920.2011.02530.x}}</ref><ref name="HodgesOlson2009">{{cite doi|10.1128/AEM.01835-08}}</ref><ref name="DavisCleft">{{cite doi|10.1080/01490450902889080}}</ref><ref name="Forget2010">{{cite doi|10.1111/j.1472-4669.2010.00247.x}}</ref><ref name="Handley2010">{{cite doi|10.1038/ismej.2010.38}}</ref><ref name="Kato2009fluid">{{cite doi|10.1111/j.1462-2920.2009.02031.x}}</ref> Zetaproteobacteria have been most commonly found at deep-sea [[hydrothermal vents]],<ref name="McAllister2011" /> though recent discovery of members of this class in near-shore environments has led to the reevaluation of Zetaproteobacteria distribution and significance.<ref name="McBeth2011">{{cite doi|10.1128/AEM.02095-10}}</ref><ref name="McBeth2013">{{cite doi|10.1111/1758-2229.12033}}</ref><ref name="McAllister2015">{{cite doi|10.1002/lno.10029}}</ref>
[[File:Loihiflank.jpg|thumb|327x192px|Microbial mats encrusted with iron oxide on the flank of Loihi Seamount, Hawaii. Microbial communities in this type of habitat can harbor microbial communities dominated by the iron-oxidizing Zetaproteobacteria.]]
[[File:Loihiflank.jpg|thumb|327x192px|Microbial mats encrusted with iron oxide on the flank of Loihi Seamount, Hawaii. Microbial communities in this type of habitat can harbor microbial communities dominated by the iron-oxidizing Zetaproteobacteria.]]


==Significance==
==Significance==
As potentially an entire class of marine iron oxidizers, the Zetaproteobacteria play a substantial role in biogeochemical cycling, both past and present. Ecologically, the Zetaproteobacteria play a major role in the engineering of their own environment through the use of the controlled deposition of mineralized iron oxides, also directly affecting the environment of other members of the microbial community.
The Zetaproteobacteria are distributed worldwide in deep sea and near shore environments at oxic/anoxic interfaces. With this wide distribution, the Zetaproteobacteria have the potential to play a substantial role in biogeochemical cycling, both past and present. Ecologically, the Zetaproteobacteria play a major role in the engineering of their own environment through the use of the controlled deposition of mineralized iron oxides, also directly affecting the environment of other members of the microbial community.


Prevalence of the Zetaproteobacteria in near-shore metal (e.g. steel) coupon biocorrosion experiments highlights the impact of these marine iron oxidizers on expensive problems such as the rusting of ship hulls, metal pilings, and pipelines.<ref name=McBeth2011 /><ref name="Dang2011" />
Prevalence of the Zetaproteobacteria in near-shore metal (e.g. steel) coupon biocorrosion experiments highlights the impact of these marine iron oxidizers on expensive problems such as the rusting of ship hulls, metal pilings, and pipelines.<ref name=McBeth2011 /><ref name="Dang2011" /><ref name="Lee2013">{{cite doi|10.1080/08927014.2013.836184}}</ref>


==Discovery==
==Discovery==
Line 26: Line 26:


==Morphology==
==Morphology==
One of the most distinctive ways of identifying circumneutral iron oxidizing bacteria visually is by identifying the structure of the mineralized [[Iron(III) oxide-hydroxide|iron oxyhydroxide]] product created during iron oxidation.<ref name="Emerson2002" /><ref name="FlemmingReview">{{cite doi|10.1146/annurev.micro.112408.134208}}</ref> Oxidized, or [[ferric]] iron is insoluble at circumneutral pH, thus the microbe must have a way of dealing with the mineralized "waste" product. It is thought that one method to accomplish this is to control the deposition of oxidized iron.<ref name="Chan2011">{{cite doi|10.1038/ismej.2010.173}}</ref><ref name=Comolli>{{cite doi|10.1111/j.1462-2920.2011.02567.x}}</ref> Some of the most common morphotypes include: amorphous particulate oxides, twisted or helical stalks (figure), sheaths, and y-shaped irregular filaments.
One of the most distinctive ways of identifying circumneutral iron oxidizing bacteria visually is by identifying the structure of the mineralized [[Iron(III) oxide-hydroxide|iron oxyhydroxide]] product created during iron oxidation.<ref name="Emerson2002" /><ref name="FlemmingReview">{{cite doi|10.1146/annurev.micro.112408.134208}}</ref> Oxidized, or [[ferric]] iron is insoluble at circumneutral pH, thus the microbe must have a way of dealing with the mineralized "waste" product. It is thought that one method to accomplish this is to control the deposition of oxidized iron.<ref name="Chan2011">{{cite doi|10.1038/ismej.2010.173}}</ref><ref name=Comolli>{{cite doi|10.1111/j.1462-2920.2011.02567.x}}</ref><ref name="Saini2013">{{cite doi|10.1111/gbi.12021}}</ref> Some of the most common morphotypes include: amorphous particulate oxides, twisted or helical stalks (figure)<ref name="Chan2011" />, sheaths<ref name="Fleming2013">{{cite doi|10.1111/1574-6941.12104}}</ref>, and y-shaped irregular filaments.


These morphologies exist both in freshwater and marine iron habitats, though common freshwater iron-oxidizing bacteria such as [[Gallionella|''Gallionella'' sp. (twisted stalk)]] and [[Leptothrix|''Leptothrix ochracea'' (sheath)]] have only extremely rarely been found in the deep sea (not significant abundance). The only currently published morphotype that has been partially resolved is the twisted stalk, which is commonly formed by [[Mariprofundus ferrooxydans|''M. ferrooxydans'']]. This bacteria is a [[Gram-negative bacteria|gram negative]] kidney-bean-shaped cell that deposits iron oxides on the [[wikt:concave|concave]] side of the cell, forming twisted stalks as it moves through its environment.<ref name="Chan2011" /><ref name=Comolli /> [[File:Mariprofundus ferrooxydans PV-1 cell and stalk TEM image.tiff|thumb|upright=1.5|[[Mariprofundus ferrooxydans]] PV-1 cell attached to twisted stalk TEM image. Image by Clara Chan.]]
These morphologies exist both in freshwater and marine iron habitats, though common freshwater iron-oxidizing bacteria such as [[Gallionella|''Gallionella'' sp. (twisted stalk)]] and [[Leptothrix|''Leptothrix ochracea'' (sheath)]] have only extremely rarely been found in the deep sea (not significant abundance). One currently published morphotype that has been partially resolved is the twisted stalk, which is commonly formed by [[Mariprofundus ferrooxydans|''M. ferrooxydans'']]. This bacteria is a [[Gram-negative bacteria|gram negative]] kidney-bean-shaped cell that deposits iron oxides on the [[wikt:concave|concave]] side of the cell, forming twisted stalks as it moves through its environment.<ref name="Chan2011" /><ref name=Comolli /> [[File:Mariprofundus ferrooxydans PV-1 cell and stalk TEM image.tiff|thumb|upright=1.5|[[Mariprofundus ferrooxydans]] PV-1 cell attached to twisted stalk TEM image. Image by Clara Chan.]] Another common Zetaproteobacteria morphotype is the sheath structure, which has yet to be isolated, but has been identified with [[Fluorescence in situ hybridization|Fluorescence in situ hybridization (FISH)]]<ref name="Fleming2013" />.


Iron oxidation morphotypes can be preserved and have been detected in ancient hydrothermal deposits.<ref name=Juniper1988>{{cite journal|last=Juniper|first=S. Kim|author2=Yves Fouquet |title=Filamentous iron-silica deposits from modern and ancient hydrothermal sites|journal=Canadian Mineralogist|year=1988|volume=26|pages=859–869}}</ref>
Iron oxidation morphotypes can be preserved and have been detected in ancient hydrothermal deposits preserved in the rock record.<ref name=Juniper1988>{{cite journal|last=Juniper|first=S. Kim|author2=Yves Fouquet |title=Filamentous iron-silica deposits from modern and ancient hydrothermal sites|journal=Canadian Mineralogist|year=1988|volume=26|pages=859–869}}</ref><ref name="Hofmann2008">{{cite doi|10.1089/ast.2007.0130}}</ref><ref name="Planavsky2009">{{cite doi|10.1016/j.epsl.2009.06.033}}</ref><ref name="Little2004">{{cite doi|10.1080/01490450490485845}}</ref><ref name="Sun2015">{{cite doi|10.1002/2014JG002764}}</ref> Some current work is focused on how the Zetaproteobacteria form microbial mats in the modern environment so that scientists can better interpret Fe biominerals found in the rock record.<ref name="Krepski2013">{{cite doi|10.1111/gbi.12043}}</ref>


==Ecology==
==Ecology==
Line 43: Line 43:
* Deep-sea [[hydrothermal vents]] associated with:
* Deep-sea [[hydrothermal vents]] associated with:
** [[hotspot (geology)|hotspots]]<ref name=Emerson2007 /><ref name=McAllister2011 /><ref name=Rassa2009>{{cite doi|10.1080/01490450903263350}}</ref><ref name="EmersonMoyer2010">{{cite doi|10.5670/oceanog.2010.67}}</ref><ref>{{cite doi|10.1080/01490450903263400}}</ref><ref>{{cite doi|10.1038/ismej.2011.48}}</ref>
** [[hotspot (geology)|hotspots]]<ref name=Emerson2007 /><ref name=McAllister2011 /><ref name=Rassa2009>{{cite doi|10.1080/01490450903263350}}</ref><ref name="EmersonMoyer2010">{{cite doi|10.5670/oceanog.2010.67}}</ref><ref>{{cite doi|10.1080/01490450903263400}}</ref><ref>{{cite doi|10.1038/ismej.2011.48}}</ref>
** [[Back-arc basin|back arc spreading centers/troughs]]<ref name=Kato2009fluid /><ref>{{cite doi|10.1111/j.1462-2920.2009.01930.x}}</ref><ref>{{cite doi|10.1029/2007JB005413}}</ref>
** [[Back-arc basin|back arc spreading centers/troughs]]<ref name=Kato2009fluid /><ref>{{cite doi|10.1111/j.1462-2920.2009.01930.x}}</ref><ref>{{cite doi|10.1029/2007JB005413}}</ref><ref name="Kato2012M">{{cite doi|10.3389/fmicb.2012.00089}}</ref>
** [[Island arcs]]<ref name=HodgesOlson2009 /><ref name=Forget2010 />
** [[Island arcs]]<ref name=HodgesOlson2009 /><ref name=Forget2010 />
*** [[Ambitle|Near-shore venting associated with a coral reef ecosystem]]<ref>{{cite doi|10.1016/j.chemgeo.2012.02.024}}</ref>
*** [[Ambitle|Near-shore venting associated with a coral reef ecosystem]]<ref>{{cite doi|10.1016/j.chemgeo.2012.02.024}}</ref>
** [[Seafloor spreading|Spreading centers (on- and off axis)]]<ref name=Schauer2011 /><ref name=DavisCleft /><ref>{{cite doi|10.1111/j.1574-6941.2012.01367.x}}</ref>
** [[Seafloor spreading|Spreading centers (on- and off axis)]]<ref name=Schauer2011 /><ref name=DavisCleft /><ref>{{cite doi|10.1111/j.1574-6941.2012.01367.x}}</ref><ref name="Dekov2010">{{cite doi|doi:10.1016/j.chemgeo.2010.09.012}}</ref><ref name="MacDonald2014">{{cite doi|10.1039/c4em00073k}}</ref><ref name="Scottness">{{cite doi|10.1371/journal.pone.0119284}}</ref><ref name="Cao2014">{{cite doi|10.1128/mBio.00980-13}}</ref>
** [[East Pacific Rise|Inactive sulfides along the East Pacific Rise (spreading center)]]<ref>{{cite doi|10.1128/mBio.00279-11}}</ref>
** [[East Pacific Rise|Inactive sulfides along the East Pacific Rise (spreading center)]]<ref>{{cite doi|10.1128/mBio.00279-11}}</ref>
** [[Caldera|Flooded caldera]]<ref name=Handley2010 />
** [[Caldera|Flooded caldera]]<ref name=Handley2010 />
** Guaymas Basin<ref>{{cite pmid|12732547}}</ref>
** Guaymas Basin<ref>{{cite pmid|12732547}}</ref>
** Massive sulfide deposits <ref name="ShingoKato2015">{{cite doi|10.1111/1462-2920.12648}}</ref>
* Deep subsurface CO2-rich springs<ref name="EmersonJ2015">{{cite doi|10.1111/1462-2920.12817}}</ref><ref name="Colman2014">{{cite doi|10.1111/gbi.12070}}</ref>
* Brine/seawater interface<ref>{{cite pmid|11425725}}</ref>
* Brine/seawater interface<ref>{{cite pmid|11425725}}</ref>
* [[Salt marsh]] sediment<ref name=McBeth2011 /><ref>{{cite doi|10.1128/AEM.03006-09}}</ref>
* [[Salt marsh]] sediment<ref name=McBeth2011 /><ref>{{cite doi|10.1128/AEM.03006-09}}</ref>
* Intertidal mixing zone of a beach [[aquifer]]<ref name="McAllister2015" /><ref name="MacDonald2014" />
* Near-shore metal biocorrosion experiments<ref name=McBeth2011 /><ref name="Dang2011">{{cite doi|10.1111/j.1462-2920.2011.02583.x}}</ref>
* Near-shore metal biocorrosion experiments<ref name=McBeth2011 /><ref name="Dang2011">{{cite doi|10.1111/j.1462-2920.2011.02583.x}}</ref>
* Stratified Chesapeake Bay estuary<ref name="MacDonald2014" />
⚫
* [[Alvinocarididae|''Rimicaris exoculata'']] (shrimp) gut at the [[Mid-Atlantic Ridge|MAR]]<ref>{{cite doi|10.1016/S0168-6496(03)00176-4}}</ref>
* [[Tsunami]] impacted soils<ref name="Asano">{{cite doi|10.1007/s00248-013-0261-9}}</ref>
⚫
* [[Alvinocarididae|''Rimicaris exoculata'']] (shrimp) gut at the [[Mid-Atlantic Ridge|MAR]]<ref>{{cite doi|10.1016/S0168-6496(03)00176-4}}</ref><ref name="Jan2014">{{cite doi|10.1111/1462-2920.12406}}</ref>
* Oxygenated [[worm]] [[trace fossil|burrows]] or bioturbated beach sands<ref name="McAllister2015" /><ref name="Stauffert2013">{{cite doi|10.1371/journal.pone.0065347}}</ref><ref name="Pischedda">{{cite doi|10.1016/j.resmic.2011.07.008}}</ref>
* Antarctica continental shelf sediment<ref>{{cite pmid|12732511}}</ref>
* Antarctica continental shelf sediment<ref>{{cite pmid|12732511}}</ref>
* Levantine Basin and continental margin<ref name="RubinBlum">{{cite doi|10.1371/journal.pone.0091456}}</ref>
* [[Mangrove]] soils<ref name="Thompson2013">{{cite doi|10.1186/2191-0855-3-65}}</ref>


===Ecological Niche===
===Ecological Niche===

Revision as of 23:13, 20 May 2015

Zetaproteobacteria
Scientific classification
Domain:
Bacteria
Phylum:
Proteobacteria
Class:
Zetaproteobacteria
Species
Mariprofundus ferrooxydans

The class Zetaproteobacteria is the sixth and most recently described class of the Proteobacteria.[1] Zetaproteobacteria can also refer to the group of organisms assigned to this class. The Zetaproteobacteria are represented by a single described species, Mariprofundus ferrooxydans,[2] which is an iron-oxidizing neutrophilic chemolithoautotroph originally isolated from Loihi Seamount in 1996 (post-eruption).[1][3] Molecular cloning techniques focusing on the small subunit ribosomal RNA gene have also been used to identify a more diverse majority of the Zetaproteobacteria that have as yet been unculturable.[4]

Regardless of culturing status, the Zetaproteobacteria show up worldwide in estuarine and marine habitats associated with opposing steep redox gradients of reduced (ferrous) iron and oxygen, either as a minor detectable component or as the dominant member of the microbial community.[5][6][7][8][9][10] Zetaproteobacteria have been most commonly found at deep-sea hydrothermal vents,[4] though recent discovery of members of this class in near-shore environments has led to the reevaluation of Zetaproteobacteria distribution and significance.[11][12][13]

Microbial mats encrusted with iron oxide on the flank of Loihi Seamount, Hawaii. Microbial communities in this type of habitat can harbor microbial communities dominated by the iron-oxidizing Zetaproteobacteria.

Significance

The Zetaproteobacteria are distributed worldwide in deep sea and near shore environments at oxic/anoxic interfaces. With this wide distribution, the Zetaproteobacteria have the potential to play a substantial role in biogeochemical cycling, both past and present. Ecologically, the Zetaproteobacteria play a major role in the engineering of their own environment through the use of the controlled deposition of mineralized iron oxides, also directly affecting the environment of other members of the microbial community.

Prevalence of the Zetaproteobacteria in near-shore metal (e.g. steel) coupon biocorrosion experiments highlights the impact of these marine iron oxidizers on expensive problems such as the rusting of ship hulls, metal pilings, and pipelines.[11][14][15]

Discovery

Mariprofundus ferrooxydans PV-1 twisted stalks TEM image. One example of Fe oxide morphotypes produced by the Zetaproteobacteria. Image by Clara Chan.

The Zetaproteobacteria were first discovered in 1991 by Craig Moyer, Fred Dobbs, and David Karl as a single rare clone in a mesophilic, or moderate temperature, hydrothermal vent field known as Pele's Vents at Loihi Seamount, Hawaii. This particular vent was dominated by sulfur-oxidizing Epsilonproteobacteria. With no close relatives known at the time, the clone was initially labeled as a Gammaproteobacteria.[16]

Subsequent isolation of two strains of M. ferrooxydans, PV-1 and JV-1,[3] along with the increasing realization that a phylogenetically distinct group of Proteobacteria (the Zetaproteobacteria) could be found globally as dominant members of bacterial communities led to the suggestion for the creation of this new class of the Proteobacteria.

Morphology

One of the most distinctive ways of identifying circumneutral iron oxidizing bacteria visually is by identifying the structure of the mineralized iron oxyhydroxide product created during iron oxidation.[3][17] Oxidized, or ferric iron is insoluble at circumneutral pH, thus the microbe must have a way of dealing with the mineralized "waste" product. It is thought that one method to accomplish this is to control the deposition of oxidized iron.[18][19][20] Some of the most common morphotypes include: amorphous particulate oxides, twisted or helical stalks (figure)[18], sheaths[21], and y-shaped irregular filaments.

These morphologies exist both in freshwater and marine iron habitats, though common freshwater iron-oxidizing bacteria such as Gallionella sp. (twisted stalk) and Leptothrix ochracea (sheath) have only extremely rarely been found in the deep sea (not significant abundance). One currently published morphotype that has been partially resolved is the twisted stalk, which is commonly formed by M. ferrooxydans. This bacteria is a gram negative kidney-bean-shaped cell that deposits iron oxides on the concave side of the cell, forming twisted stalks as it moves through its environment.[18][19]

Mariprofundus ferrooxydans PV-1 cell attached to twisted stalk TEM image. Image by Clara Chan.

Another common Zetaproteobacteria morphotype is the sheath structure, which has yet to be isolated, but has been identified with Fluorescence in situ hybridization (FISH)[21].

Iron oxidation morphotypes can be preserved and have been detected in ancient hydrothermal deposits preserved in the rock record.[22][23][24][25][26] Some current work is focused on how the Zetaproteobacteria form microbial mats in the modern environment so that scientists can better interpret Fe biominerals found in the rock record.[27]

Ecology

Phylogenetic tree showing the phylogenetic placement of the Zetaproteobacteria (orange branches) within the Proteobacteria. Asterisks highlight the Zetaproteobacteria cultured isolates.

Biodiversity

An operational taxonomic unit, or an OTU, allows a microbiologist to define a bacterial taxa using defined similarity bins based on a gene of interest. In microbial ecology, the small subunit ribosomal RNA gene is generally used at a cut off of 97% similarity to define an OTU. In the most basic sense, the OTU represents a bacterial species.

For the Zetaproteobacteria, 28 OTUs have been defined.[4] Of interest were the two globally distributed OTUs that dominated the phylogenetic tree, two OTUs that seemed to originate in the deep subsurface,[10] and several endemic OTUs, along with the relatively limited detection of the isolated Zetaproteobacteria representative.

Habitats

Ecological Niche

All of the habitats where Zetaproteobacteria have been found have (at least) one thing in common: they all provide an interface of steep redox gradients of oxygen and iron.[56]

Reduced hydrothermal fluids, for instance, exiting from vents in the deep-sea carry with them high concentrations of ferrous iron and other reduced chemical species, creating a gradient upward through a microbial mat of high to low ferrous iron. Similarly, oxygen from the overlying seawater diffuses into the microbial mat resulting in a downward gradient of high to low oxygen. Zetaproteobacteria are thought to live at the interface, where there is enough oxygen for use as an electron acceptor without there being too much oxygen for the organism to compete with the increased rate of chemical oxidation, and where there is enough ferrous iron for growth.[17][56]

Iron oxidation is not always energetically favorable. Reference[57] discusses favorable conditions for iron oxidation in habitats that otherwise may have been thought to be dominated by the more energy yielding metabolisms of hydrogen or sulfur oxidation.

Note: Iron is not the only reduced chemical species accociated with these redox gradient environments. It is likely that Zetaproteobacteria are not all iron oxidizers.

Metabolism

Iron oxidation pathways in both freshwater acidophilic and circumneutral iron oxidation habitats such as acid mine drainage or groundwater iron seeps, respectively, though not complete, are better understood than marine circumneutral iron oxidation.

The genome for the only described cultured representative of the Zetaproteobacteria was recently published, and while no definitive iron oxidation genes were identified, the gene neighborhood of a molybdopterin oxidoreductase protein was identified as a place to start looking at candidate iron oxidation pathway genes.[58] Though M. ferrooxydans was isolated as an autotroph, able to fix carbon dioxide, the genome of PV-1 revealed an ability to grow mixotrophically on fructose or mannose.

It is difficult at this point to speculate on the metabolism of the entire class with the limited sample size.

See also

References

  1. ^ a b c Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1371/journal.pone.0000667, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1371/journal.pone.0000667 instead.
  2. ^ mariprofundus in LPSN; Parte, Aidan C.; Sardà Carbasse, Joaquim; Meier-Kolthoff, Jan P.; Reimer, Lorenz C.; Göker, Markus (1 November 2020). "List of Prokaryotic names with Standing in Nomenclature (LPSN) moves to the DSMZ". International Journal of Systematic and Evolutionary Microbiology. 70 (11): 5607–5612. doi:10.1099/ijsem.0.004332.
  3. ^ a b c Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 12039770, please use {{cite journal}} with |pmid=12039770 instead.
  4. ^ a b c d Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1128/AEM.00533-11, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1128/AEM.00533-11 instead.
  5. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1462-2920.2011.02530.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1462-2920.2011.02530.x instead.
  6. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1128/AEM.01835-08, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1128/AEM.01835-08 instead.
  7. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1080/01490450902889080, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1080/01490450902889080 instead.
  8. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1472-4669.2010.00247.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1472-4669.2010.00247.x instead.
  9. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/ismej.2010.38, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1038/ismej.2010.38 instead.
  10. ^ a b c Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/j.1462-2920.2009.02031.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1111/j.1462-2920.2009.02031.x instead.
  11. ^ a b c d Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1128/AEM.02095-10, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1128/AEM.02095-10 instead.
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  22. ^ Juniper, S. Kim; Yves Fouquet (1988). "Filamentous iron-silica deposits from modern and ancient hydrothermal sites". Canadian Mineralogist. 26: 859–869.
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