Hydrogen-oxidizing bacteria: Difference between revisions
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'''Hydrogen oxidizing bacteria''' are a group of facultative autotrophs that can use hydrogen as electron donor. |
'''Hydrogen oxidizing bacteria''' are a group of facultative autotrophs that can use hydrogen as electron donor. |
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They can be divided into aerobics and anaerobics. The former use [[hydrogen]] as an [[electron donor]] and oxygen as an acceptor while the latter use sulphate or nitrogen dioxide as [[Electron acceptor|electron acceptors]] |
They can be divided into aerobics and anaerobics. The former use [[hydrogen]] as an [[electron donor]] and oxygen as an acceptor while the latter use sulphate or nitrogen dioxide as [[Electron acceptor|electron acceptors]].<ref>{{cite book |last=Aragno |first=Michel |last2=Schlegel |first2=Hans G. | name-list-format = vanc | chapter =The Hydrogen-Oxidizing Bacteria |date=1981 |title = The Prokaryotes: A Handbook on Habitats, Isolation, and Identification of Bacteria|pages=865–893|editor-last=Starr|editor-first=Mortimer P.|editor2-last=Stolp|editor2-first=Heinz |editor3-last=Trüper |editor3-first=Hans G. |editor4-last=Balows |editor4-first=Albert |publisher=Springer Berlin Heidelberg |doi=10.1007/978-3-662-13187-9_70 |isbn=978-3-662-13187-9}}</ref> Some species of both bacteria types have been isolated in different environments, for example in fresh waters, sediments, soils, activated sludge, hot springs, hydrothermal vents and percolating water <ref>{{cite journal | vauthors = Koskinen PE, Beck SR, Orlygsson J, Puhakka JA | title = Ethanol and hydrogen production by two thermophilic, anaerobic bacteria isolated from Icelandic geothermal areas | journal = Biotechnology and Bioengineering | volume = 101 | issue = 4 | pages = 679–90 | date = November 2008 | pmid = 18500766 | doi = 10.1002/bit.21942 }}</ref>. |
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These organisms are able to exploit the special properties of molecular hydrogen (for instance redox potential and diffusion coefficient) thanks to the presence of hydrogenases <ref>{{ |
These organisms are able to exploit the special properties of molecular hydrogen (for instance redox potential and diffusion coefficient) thanks to the presence of hydrogenases <ref>{{cite journal | vauthors = Barz M, Beimgraben C, Staller T, Germer F, Opitz F, Marquardt C, Schwarz C, Gutekunst K, Vanselow KH, Schmitz R, LaRoche J, Schulz R, Appel J | display-authors = 6 | title = Distribution analysis of hydrogenases in surface waters of marine and freshwater environments | journal = PloS One | volume = 5 | issue = 11 | pages = e13846 | date = November 2010 | pmid = 21079771 | doi = 10.1371/journal.pone.0013846 | bibcode = 2010PLoSO...513846B }}</ref>. The aerobic hydrogen oxidizing bacteria are facultative [[Autotroph|autotrophs]], but they can also have mixotrophic or completely [[Heterotroph|heterotrophic]] growth. Most of them show greater growth on organic substrates.The use of hydrogen as an electron donor coupled with the ability to synthesize organic mutter, through the reductive assimilation of CO<sub>2</sub>, characterize the hydrogen oxidizing bacteria. Among the most represented genres of these organisms we find: [[Caminibacter]], [[Aquifex]], [[Ralstonia]] and [[Paracoccus]]. |
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== Hydrogen production and its distribution in the oceans == |
== Hydrogen production and its distribution in the oceans == |
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The most widespread compound on our [[Earth]] is [[hydrogen]], which represents around three-quarters of all the [[Chemical element|elements]].<ref name=":02">{{ |
The most widespread compound on our [[Earth]] is [[hydrogen]], which represents around three-quarters of all the [[Chemical element|elements]].<ref name=":02">{{cite journal| vauthors = Das D, Veziroǧlu TN |date=2001-01-01|title=Hydrogen production by biological processes: a survey of literature|journal=International Journal of Hydrogen Energy|volume=26|issue=1|pages=13–28|doi=10.1016/S0360-3199(00)00058-6|issn=0360-3199}}</ref> In the [[atmosphere]], its concentration is about 0.5-0.6 ppm and so here it represents the most abundant [[trace gas]], after [[methane]].<ref name=":42">{{cite journal | vauthors = Barz M, Beimgraben C, Staller T, Germer F, Opitz F, Marquardt C, Schwarz C, Gutekunst K, Vanselow KH, Schmitz R, LaRoche J, Schulz R, Appel J | display-authors = 6 | title = Distribution analysis of hydrogenases in surface waters of marine and freshwater environments | journal = PloS One | volume = 5 | issue = 11 | pages = e13846 | date = November 2010 | pmid = 21079771 | doi = 10.1371/journal.pone.0013846 | bibcode = 2010PLoSO...513846B }}</ref> Therefore, H<sub>2</sub> can be used as [[energy]] source in several biological processes, also because it has a highly negative [[redox potential]] (E<sub>0</sub>’= -0.414 V) . It can be coupled with different compounds: |
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- O<sub>2</sub>: the oxic respiration is performed (H<sub>2</sub>+1/2O<sub>2</sub> → H<sub>2</sub>O) |
- O<sub>2</sub>: the oxic respiration is performed (H<sub>2</sub>+1/2O<sub>2</sub> → H<sub>2</sub>O) |
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- Oxidized compounds, such as [[carbon dioxide]] or [[sulfate]]. <ref>{{ |
- Oxidized compounds, such as [[carbon dioxide]] or [[sulfate]]. <ref>{{cite journal | vauthors = Heimann A, Jakobsen R, Blodau C | title = Energetic constraints on H2-dependent terminal electron accepting processes in anoxic environments: a review of observations and model approaches | journal = Environmental Science & Technology | volume = 44 | issue = 1 | pages = 24–33 | date = January 2010 | pmid = 20039730 | doi = 10.1021/es9018207 | bibcode = 2010EnST...44...24H }}</ref> |
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In the ecosystems, hydrogen can be produced through biological and abiotic processes . |
In the ecosystems, hydrogen can be produced through biological and abiotic processes . |
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The abiotic processes are mainly due to geothermal production <ref name=":12">{{ |
The abiotic processes are mainly due to geothermal production <ref name=":12">{{cite book |last=Aragno |first=Michel | name-list-format = vanc |chapter=Thermophilic, Aerobic, Hydrogen-Oxidizing (Knallgas) Bacteria|date=1992|work=The Prokaryotes: A Handbook on the Biology of Bacteria: Ecophysiology, Isolation, Identification, Applications|pages=3917–3933|editor-last=Balows|editor-first=Albert|publisher=Springer New York|language=en|doi=10.1007/978-1-4757-2191-1_55|isbn=978-1-4757-2191-1|editor2-last=Trüper|editor2-first=Hans G.|editor3-last=Dworkin|editor3-first=Martin|editor4-last=Harder|editor4-first=Wim|title=The Prokaryotes}}</ref> and [[serpentinization]] <ref name=":22">{{cite journal | vauthors = Brazelton WJ, Nelson B, Schrenk MO | title = Metagenomic evidence for h(2) oxidation and h(2) production by serpentinite-hosted subsurface microbial communities | journal = Frontiers in Microbiology | volume = 2 | pages = 268 | date = 2012 | pmid = 22232619 | pmc = 3252642 | doi = 10.3389/fmicb.2011.00268 }}</ref>. In the first case, hydrogen is usually present as a [[gas]] and probably can be obtained by different reactions: |
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1. Water may react with [[silicon]] radical at high temperature: |
1. Water may react with [[silicon]] radical at high temperature: |
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On the other hand, serpentinization is an exothermic geochemical mechanism that occurs when, thanks to the [[Tectonics|tectonic]] movements, the ultramafic rocks raise and reach the water. This process can bring to the production of large quantities of H<sub>2</sub>, but also of [[methane]] and organic substances. <ref name=":22" /> |
On the other hand, serpentinization is an exothermic geochemical mechanism that occurs when, thanks to the [[Tectonics|tectonic]] movements, the ultramafic rocks raise and reach the water. This process can bring to the production of large quantities of H<sub>2</sub>, but also of [[methane]] and organic substances. <ref name=":22" /> |
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The main mechanisms that lead to the formation of hydrogen, involving different microorganisms, are [[nitrogen fixation]] and [[fermentation]]. The first one happens in some bacteria, such as heterocystous and non-heterocystous [[cyanobacteria]], that have a specialized enzyme, the [[nitrogenase]], which catalizes the reduction of N<sub>2</sub> to NH<sub>4</sub><sup>+</sup>. In addition, these microorganisms have another enzyme, the [[hydrogenase]], that oxidizes the H<sub>2</sub> released as a by-product. <ref name=":02" /> Therefore, in this type of bacteria, the amount of hydrogen produced depends on the ratio between H<sub>2</sub> production and consumption.<ref name=":32">{{ |
The main mechanisms that lead to the formation of hydrogen, involving different microorganisms, are [[nitrogen fixation]] and [[fermentation]]. The first one happens in some bacteria, such as heterocystous and non-heterocystous [[cyanobacteria]], that have a specialized enzyme, the [[nitrogenase]], which catalizes the reduction of N<sub>2</sub> to NH<sub>4</sub><sup>+</sup>. In addition, these microorganisms have another enzyme, the [[hydrogenase]], that oxidizes the H<sub>2</sub> released as a by-product. <ref name=":02" /> Therefore, in this type of bacteria, the amount of hydrogen produced depends on the ratio between H<sub>2</sub> production and consumption.<ref name=":32">{{cite journal |last=Tiwari |first=Archana |last2=Pandey |first2=Anjana | name-list-format = vanc |date=January 2012 |title=Cyanobacterial hydrogen production – A step towards clean environment |journal=International Journal of Hydrogen Energy|volume=3 7 |issue=1 |pages=139–150 |doi=10.1016/j.ijhydene.2011.09.100 }}</ref> In some cases, the H<sub>2</sub> can be present in the environments because the N<sub>2</sub>-fixing bacteria can have a low quantity of hydrogenases. <ref>{{cite journal | vauthors = Pumphrey GM, Ranchou-Peyruse A, Spain JC | title = Cultivation-independent detection of autotrophic hydrogen-oxidizing bacteria by DNA stable-isotope probing | journal = Applied and Environmental Microbiology | volume = 77 | issue = 14 | pages = 4931–8 | date = July 2011 | pmid = 21622787 | doi = 10.1128/aem.00285-11 }}</ref><ref name=":32" /> Instead, [[fermentation]] is performed by some strict or facultative anaerobic [[Heterotroph|heterotrophic]] bacteria, in particular [[Clostridia]] <ref>{{cite journal | vauthors = Adams MW, Stiefel EI | title = Biological hydrogen production: not so elementary | journal = Science | volume = 282 | issue = 5395 | pages = 1842–3 | date = December 1998 | pmid = 9874636 | doi = 10.1126/science.282.5395.1842 }}</ref> ,that degrade organic molecules, producing hydrogen as one of the products. Therefore, this type of [[metabolism]] mainly occurs in anoxic sites, such as lake [[Sediment|sediments]], deep-sea [[Hydrothermal vent|hydrothermal vents]] and human gut. <ref>{{cite journal | vauthors = Adam N, Perner M | title = Microbially Mediated Hydrogen Cycling in Deep-Sea Hydrothermal Vents | journal = Frontiers in Microbiology | volume = 9 | pages = 2873 | date = 2018 | pmid = 30532749 | pmc = 6265342 | doi = 10.3389/fmicb.2018.02873 }}</ref> |
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Probably mainly due to the biotic processes, in the marine habitats it was observed that the concentrations of hydrogen were supersaturated. In all these environments, the highest concentrations were in the first metres, decreasing to the [[thermocline]] and reaching the lowest concentrations in the deep [[Ocean|oceans]]. <ref name=":42" /> Globally, [[Tropics|tropical]] and [[Subtropics|subtropical]] oceans appear to have the most abundant quantity of H<sub>2</sub> <ref name=":52">{{ |
Probably mainly due to the biotic processes, in the marine habitats it was observed that the concentrations of hydrogen were supersaturated. In all these environments, the highest concentrations were in the first metres, decreasing to the [[thermocline]] and reaching the lowest concentrations in the deep [[Ocean|oceans]]. <ref name=":42" /> Globally, [[Tropics|tropical]] and [[Subtropics|subtropical]] oceans appear to have the most abundant quantity of H<sub>2</sub> <ref name=":52">{{cite journal|last=Herr|first=Frank L.|last2=Frank|first2=Ernest C.|last3=Leone|first3=Gerald M.|last4=Kennicutt|first4=Mahlon C.| name-list-format = vanc |date=January 1984|title=Diurnal variability of dissolved molecular hydrogen in the tropical South Atlantic Ocean|journal=Deep Sea Research Part A. Oceanographic Research Papers|volume=31|issue=1|pages=13–20|doi=10.1016/0198-0149(84)90069-4|issn=0198-0149|bibcode=1984DSRA...31...13H}}</ref><ref name=":42" /><ref name=":62">{{cite journal|last=Conrad|first=Ralf|last2=Seiler|first2=Wolfgang| name-list-format = vanc |date=December 1988|title=Methane and hydrogen in seawater (Atlantic Ocean)|journal=Deep Sea Research Part A. Oceanographic Research Papers|volume=35|issue=12|pages=1903–1917|doi=10.1016/0198-0149(88)90116-1|issn=0198-0149|bibcode=1988DSRA...35.1903C}}</ref>, while the least amount is present in higher [[Latitude|latitudes]] <ref name=":42" /><ref>{{cite journal|last=Herr|first=Frank L.|last2=Scranton|first2=Mary I.|last3=Barger|first3=William R.| name-list-format = vanc |date=September 1981|title=Dissolved hydrogen in the Norwegian Sea: Mesoscale surface variability and deep-water distribution|journal=Deep Sea Research Part A. Oceanographic Research Papers|volume=28|issue=9|pages=1001–1016|doi=10.1016/0198-0149(81)90014-5|issn=0198-0149|bibcode=1981DSRA...28.1001H}}</ref><ref>{{cite journal |last=Punshon |first=Stephen |last2=Moore |first2=Robert M. |last3=Xie|first3=Huixiang| name-list-format = vanc |date=April 2007|title=Net loss rates and distribution of molecular hydrogen (H2) in mid-latitude coastal waters|journal=Marine Chemistry|volume=105|issue=1–2|pages=129–139|doi=10.1016/j.marchem.2007.01.009|issn=0304-4203}}</ref>. However, it was observed that the realease of hydrogen in the oceans is dependent on the solar [[radiation]], showing a daily change with the maximum peak at noon <ref name=":42" /><ref name=":52" /><ref name=":62" />. Nitrogen fixation, performed by cyanobacteria, leads to the production of one molecule of H<sub>2</sub> at least. This metabolism is thought to be the major one involved in the increase of H<sub>2</sub> in the oceans .<ref name=":42" /> Despite there are some evidences of this,<ref>{{cite journal | vauthors = Lindberg P, Lindblad P, Cournac L | title = Gas exchange in the filamentous cyanobacterium Nostoc punctiforme strain ATCC 29133 and Its hydrogenase-deficient mutant strain NHM5 | journal = Applied and Environmental Microbiology | volume = 70 | issue = 4 | pages = 2137–45 | date = April 2004 | pmid = 15066806 | doi = 10.1128/aem.70.4.2137-2145.2004 }}</ref><ref>{{cite journal| vauthors = Wilson ST, Foster RA, Zehr JP, Karl DM |date=2010-04-08|title=Hydrogen production by Trichodesmium erythraeum Cyanothece sp. and Crocosphaera watsonii |journal=Aquatic Microbial Ecology |volume=59 |pages=197–206 |doi=10.3354/ame01407 }}</ref> more data need to be collected to finally correlate the two phenomena. |
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== Hydrogen oxidizing bacteria in Hydrothermal vents == |
== Hydrogen oxidizing bacteria in Hydrothermal vents == |
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H<sub>2</sub> is an important [[electron donor]] in a particular environment: Hydrothermal vents. In this environment hydrogen oxidation represents a significant origin of energy, sufficient to conduct ATP synthesis and [[Autotroph|autotrophic]] CO<sub>2</sub> fixation so hydrogen oxidizing bacteria are relevant in deep sea habitats. Among the main [[Chemosynthesis|chemosynthetic]] reactions that take place in [[Hydrothermal vent|hydrothermal vents]], the oxidation of the sulphide and the hydrogen one covers a central role. In particular, for autotrophic carbon fixation, hydrogen oxidation metabolism is more favored than the sulfide/thiosulfate oxidation, although less energy is released (only -237 kJ/mol compared to – 797 kJ/mol)<ref>{{ |
H<sub>2</sub> is an important [[electron donor]] in a particular environment: Hydrothermal vents. In this environment hydrogen oxidation represents a significant origin of energy, sufficient to conduct ATP synthesis and [[Autotroph|autotrophic]] CO<sub>2</sub> fixation so hydrogen oxidizing bacteria are relevant in deep sea habitats. Among the main [[Chemosynthesis|chemosynthetic]] reactions that take place in [[Hydrothermal vent|hydrothermal vents]], the oxidation of the sulphide and the hydrogen one covers a central role. In particular, for autotrophic carbon fixation, hydrogen oxidation metabolism is more favored than the sulfide/thiosulfate oxidation, although less energy is released (only -237 kJ/mol compared to – 797 kJ/mol)<ref>{{cite journal | vauthors = Adam N, Perner M | title = Microbially Mediated Hydrogen Cycling in Deep-Sea Hydrothermal Vents | journal = Frontiers in Microbiology | volume = 9 | pages = 2873 | date = 2018-11-23 | pmid = 30532749 | doi = 10.3389/fmicb.2018.02873 }}</ref>. To fix a [[Mole (unit)|mole]] of carbon during the hydrogen oxidation, one third of the energy necessary for the sulphide oxidation is used. This is due to the [[Reduction potential|redox potential]] of hydrogen, which is more negative than NAD (P)/H. Based on the amount of sulphide, hydrogen and other farm biotics, this phenomenon can be intensified leading, in some cases, to an energy production by oxidation of the hydrogen of 10 -18 times higher than produced one by the sulphide oxidation <ref>{{cite journal | vauthors = Anantharaman K, Breier JA, Sheik CS, Dick GJ | title = Evidence for hydrogen oxidation and metabolic plasticity in widespread deep-sea sulfur-oxidizing bacteria | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 1 | pages = 330–5 | date = January 2013 | pmid = 23263870 | doi = 10.1073/pnas.1215340110 }}</ref><ref>{{cite book|title=Hydrogen is an energy source for hydrothermal vent symbioses|last=M. Petersen, Jillian U. Zielinski, Frank Pape, Thomas Seifert, Richard Moraru, Cristina Amann, Rudolf Hourdez, Stephane R. Girguis, Peter D. Wankel, Scott Barbe, Valerie Pelletier, Eric Fink, Dennis Borowski, Christian Bach, Wolfgang Nicole, Dubilier|oclc=866919946}}</ref> . |
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== Knallgas-bacteria == |
== Knallgas-bacteria == |
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'''Aerobic Hydrogen oxidizing bacteria''', or sometimes '''''Knallgas''-bacteria''', are [[bacteria]] that oxidize [[hydrogen]] as a source of energy with oxygen as final electron acceptor. See [[microbial metabolism]] ([[Microbial metabolism#Hydrogen oxidation|hydrogen oxidation]]). These bacteria include ''[[Hydrogenobacter thermophilus]]'', ''[[Cupriavidus necator]]'', ''[[Hydrogenovibrio marinus]]'', and ''[[Helicobacter pylori]]''.<ref>Olson JW and Maier RJ (2002) Molecular hydrogen as an energy source for Helicobacter pylori. Science 298:1788-90. [http://science.sciencemag.org/content/298/5599/1788.long full text]</ref> There are both [[Gram positive]] and [[Gram negative]] knallgas bacteria. |
'''Aerobic Hydrogen oxidizing bacteria''', or sometimes '''''Knallgas''-bacteria''', are [[bacteria]] that oxidize [[hydrogen]] as a source of energy with oxygen as final electron acceptor. See [[microbial metabolism]] ([[Microbial metabolism#Hydrogen oxidation|hydrogen oxidation]]). These bacteria include ''[[Hydrogenobacter thermophilus]]'', ''[[Cupriavidus necator]]'', ''[[Hydrogenovibrio marinus]]'', and ''[[Helicobacter pylori]]''.<ref>Olson JW and Maier RJ (2002) Molecular hydrogen as an energy source for Helicobacter pylori. Science 298:1788-90. [http://science.sciencemag.org/content/298/5599/1788.long full text]</ref> There are both [[Gram positive]] and [[Gram negative]] knallgas bacteria. |
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Most grow best under [[microaerobic]] conditions. They do this because the [[hydrogenase]] [[enzyme]] used in hydrogen oxidation is inhibited by the presence of oxygen, but oxygen is still needed as a terminal [[electron acceptor]].<ref>{{ |
Most grow best under [[microaerobic]] conditions. They do this because the [[hydrogenase]] [[enzyme]] used in hydrogen oxidation is inhibited by the presence of oxygen, but oxygen is still needed as a terminal [[electron acceptor]].<ref>{{cite journal|last=Jugder|first=Bat-Erdene|last2=Welch|first2=Jeffrey|last3=Aguey-Zinsou|first3=Kondo-Francois|last4=Marquis|first4=Christopher P.| name-list-format = vanc |date=2013|title=Fundamentals and electrochemical applications of [Ni–Fe]-uptake hydrogenases|journal=RSC Advances|volume=3|issue=22|pages=8142|doi=10.1039/c3ra22668a|issn=2046-2069}}</ref> |
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The word ''[[wikt:Knallgas|Knallgas]]'' means "[[oxyhydrogen]]" (a mixture of hydrogen and oxygen, literally "bang-gas") in [[Germanic languages]]. |
The word ''[[wikt:Knallgas|Knallgas]]'' means "[[oxyhydrogen]]" (a mixture of hydrogen and oxygen, literally "bang-gas") in [[Germanic languages]]. |
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=== Strain MH-110 === |
=== Strain MH-110 === |
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Ocean’s surface water is characterised by a high concentration of [[hydrogen]] <ref>{{ |
Ocean’s surface water is characterised by a high concentration of [[hydrogen]] <ref>{{cite journal|last=Conrad|first=Ralf|last2=Seiler|first2=Wolfgang| name-list-format = vanc |date=11 July 1988|title=Methane and hydrogen in seawater (Atlantic Ocean)|journal=Deep Sea Research Part A. Oceanographic Research Papers|volume=35|issue=12|pages=1903–1917|doi=10.1016/0198-0149(88)90116-1|bibcode=1988DSRA...35.1903C}}</ref>. In 1989, for the first time, an aerobic hydrogen oxidizing bacteria was isolated from sea water and the discovery of this strain was very important also because for the first time a hydrogen oxidizing bacteria was identified in normal temperature condition. Experimentally it has been shown that the MH-110 strain is able to grow in an atmosphere (under a continuous gas flow system) characterized by an [[oxygen]] concentration of 40% (analogue characteristics are present in the surface water from which the bacteria were isolated which is, in fact, a fairly aerated region). This differs from the usual behaviour of hydrogen oxidizing bacteria which in general thrive strictly under [[Microaerophile|microaerophilic]] conditions (<10% O<sub>2</sub>).<ref>{{cite journal |last=Nishihara |first=Hirofumi |last2=Igarashi|first2=Yasuo |last3=Kodama |first3=Tohru| name-list-format = vanc |date=1989-06-01 |title=Isolation of an obligately chemolithoautotrophic, halophilic and aerobic hydrogen-oxidizing bacterium from marine environment|journal=Archives of Microbiology |volume=152|issue=1|pages=39–43|doi=10.1007/BF00447009|issn=1432-072X}}</ref><ref>{{cite journal|last= Nishihara |first= Hirofumi |last2= Igabashi |first2= Yasuo |last3= Kodama |first3= Tohruy | name-list-format = vanc |date=1991|title=Hydrogenovibrio marinus gen. nov., sp. nov., a Marine Obligately Chemolithoautotrophic Hydrogen-Oxidizing Bacterium|journal=International Journal of Systematic and Evolutionary Microbiology|volume=41|issue=1|pages=130–133|doi=10.1099/00207713-41-1-130|issn=1466-5026}}</ref> |
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This strain is also capable to couple the Hydrogen oxidation with the reduction of sulfur compounds such as thiosulfate and tetrathionate. |
This strain is also capable to couple the Hydrogen oxidation with the reduction of sulfur compounds such as thiosulfate and tetrathionate. |
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==== Knallgas bacteria : metabolism ==== |
==== Knallgas bacteria : metabolism ==== |
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The '''aerobic hydrogen oxidizing bacteria''', more known as '''Knallgas bacteria''', are a group of bacteria which are able to fix carbon dioxide using H<sub>2</sub> as electron donor and energy source and O<sub>2</sub> as terminal electron acceptor. Actually, Knallgas bacteria stand out from the [[hydrogen]] oxydizing bacteria which, although using H<sub>2</sub> as an electron donor, are not able to fix [[Carbon dioxide|CO<sub>2</sub>]], as Knallgas do. <ref>{{ |
The '''aerobic hydrogen oxidizing bacteria''', more known as '''Knallgas bacteria''', are a group of bacteria which are able to fix carbon dioxide using H<sub>2</sub> as electron donor and energy source and O<sub>2</sub> as terminal electron acceptor. Actually, Knallgas bacteria stand out from the [[hydrogen]] oxydizing bacteria which, although using H<sub>2</sub> as an electron donor, are not able to fix [[Carbon dioxide|CO<sub>2</sub>]], as Knallgas do. <ref>{{cite web|url=https://skemman.is/bitstream/1946/1741/1/Physiological%20and%20phylogenetic%20studies%20of%20thermophilic%2C%20hydrogen%20and%20sulfur%20oxidizing%20bacteria%20isolated%20from%20Icelandic%20geothermal%20areas.pdf|title=Physiological and phylogenetic studies of thermophilic, hydrogen and sulfur oxidizing bacteria isolated from Icelandic geothermal areas|first=Hildur | last = Vésteinsdòttir | name-list-format = vanc |date=2008|website=|url-status=live|archive-url=|archive-date=|access-date=}}</ref> |
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This '''aerobic hydrogen oxidation''', also known as the Knallgas reaction, which releases a considerable amount of energy, determines the formation of [[Proton-motive force|proton motive force]] (PMF). |
This '''aerobic hydrogen oxidation''', also known as the Knallgas reaction, which releases a considerable amount of energy, determines the formation of [[Proton-motive force|proton motive force]] (PMF). |
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H<sub>2</sub> + O<sub>2</sub> <math>\longrightarrow</math> H<sub>2</sub>O ΔG<sup>0</sup> = -237 Kj |
H<sub>2</sub> + O<sub>2</sub> <math>\longrightarrow</math> H<sub>2</sub>O ΔG<sup>0</sup> = -237 Kj |
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The key enzymes involved in this reaction are the [[Hydrogenase maturation protease family|hydrogenase]] which lead the electrons through the [[electron transport chain]], from hydrogen to the final acceptor, that is O<sub>2</sub> which is actually reduced in water, the only by-product.<ref>{{ |
The key enzymes involved in this reaction are the [[Hydrogenase maturation protease family|hydrogenase]] which lead the electrons through the [[electron transport chain]], from hydrogen to the final acceptor, that is O<sub>2</sub> which is actually reduced in water, the only by-product.<ref>{{cite journal | vauthors = Bowien B, Schlegel HG | title = Physiology and biochemistry of aerobic hydrogen-oxidizing bacteria | journal = Annual Review of Microbiology | volume = 35 | issue = 1 | pages = 405–52 | date = 1981-10-01 | pmid = 6271040 | doi = 10.1146/annurev.mi.35.100181.002201 }}</ref> The hydrogenases that are divided into three categories according to the type of metal present in the active site, are the enzymes that allow the oxidation of hydrogen. The first evidence of the presence of these enzymes has been found for the first time in ''[[Pelomonas saccharophila|Pseudomonas saccharophila]]'', ''[[Alcaligenes ruhlandii]]'' and ''[[Alcaligenes eutrophus|Alcaligenese eutrophus]]'' in which there were two types of hydrogenases: cytoplasmatic and membrane-bound. If the first enzyme takes up hydrogen and reduce the [[Nicotinamide adenine dinucleotide|NAD<sup>+</sup>]] in [[Nicotinamide adenine dinucleotide|NADH]] for carbon fixation, the second is involved in the generation of the proton motive force. <ref>{{cite journal | vauthors = Schink B, Schlegel HG | title = Hydrogen metabolism in aerobic hydrogen-oxidizing bacteria | journal = Biochimie | volume = 60 | issue = 3 | pages = 297–305 | date = 1978-06-13 | pmid = 667183 | doi = 10.1016/S0300-9084(78)80826-8 }}</ref><ref>{{cite journal|last=Appel|first=Jens|last2=Schulz|first2=Rüdiger| name-list-format = vanc |date=1998-11-01|title=Hydrogen metabolism in organisms with oxygenic photosynthesis: hydrogenases as important regulatory devices for a proper redox poising?|journal=Journal of Photochemistry and Photobiology B: Biology|volume=47|issue=1|pages=1–11|doi=10.1016/S1011-1344(98)00179-1|issn=1011-1344}}</ref> Anyway, in most of the knallgas bacteria only one type of hydrogensase was observed, the one bound to the membrane that provided hydrogen activation.<ref>{{cite journal | vauthors = Schneider K, Schlegel HG | title = Localization and stability of hydrogenases from aerobic hydrogen bacteria | journal = Archives of Microbiology | volume = 112 | issue = 3 | pages = 229–38 | date = April 1977 | pmid = 871226 | doi = 10.1007/BF00413086 }}</ref> |
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These microorganisms are also defined as facultative [[Autotroph|authotrophs]], neverthless some of them are also able to live in completly [[Heterotroph|heterotrophic]] conditions using organic substances as electron donor and energy source, even if in this case the hydrogenase activity takes on less importance or is completely absent. |
These microorganisms are also defined as facultative [[Autotroph|authotrophs]], neverthless some of them are also able to live in completly [[Heterotroph|heterotrophic]] conditions using organic substances as electron donor and energy source, even if in this case the hydrogenase activity takes on less importance or is completely absent.<ref>{{cite book |last=Aragno|first=Michel | name-list-format = vanc |chapter =The Hydrogen-Oxidizing Bacteria|date=1981|title =The Prokaryotes: A Handbook on Habitats, Isolation, and Identification of Bacteria|pages=865–893|editor-last=Starr|editor-first=Mortimer P.|publisher=Springer Berlin Heidelberg|language=en|doi=10.1007/978-3-662-13187-9_70|isbn=978-3-662-13187-9|last2=Schlegel|first2=Hans G.|editor2-last=Stolp|editor2-first=Heinz|editor3-last=Trüper|editor3-first=Hans G.|editor4-last=Balows|editor4-first=Albert}}</ref> |
||
However, Knallgas bacteria, growing as [[Chemolitoautotrophs|chemolithoautotrophs]], as soon as they integrate every molecule of Co<sub>2</sub>, they can produce, through the [[Calvin cycle|Calvin Benson Cycle]] or reverse citric acid cycle ([[TCA Cycle|TCA cycle]]), biomolecules necessary for the cell.<ref>{{ |
However, Knallgas bacteria, growing as [[Chemolitoautotrophs|chemolithoautotrophs]], as soon as they integrate every molecule of Co<sub>2</sub>, they can produce, through the [[Calvin cycle|Calvin Benson Cycle]] or reverse citric acid cycle ([[TCA Cycle|TCA cycle]]), biomolecules necessary for the cell.<ref>{{cite book | vauthors = Schlegel HG, Eberhardt U |chapter=Regulatory Phenomena in the Metabolism of Knallgasbacteria|date=1972-01-01|volume=7|pages=205–242| veditors = Rose AH, Tempest DW |publisher=Academic Press|doi=10.1016/s0065-2911(08)60079-x|title=Advances in Microbial Physiology Volume 7|series=Advances in Microbial Physiology|isbn=9780120277070}}</ref><ref>{{cite book|url=https://trove.nla.gov.au/version/51426340|title=Brock, biology of microorganisms |last=Madigan |first=Michael T. |last2=Martinko |first2=John M |last3=Parker |first3=Jack |last4=Brock |first4=Thomas D. | name-list-format = vanc |date=2003|publisher=Upper Saddle River, N.J Prentice Hall|year=2003|isbn=978-0-13-049147-3|edition=10th ed |location=|pages=}}</ref> |
||
6H<sub>2</sub> + 2O<sub>2</sub> + CO<sub>2</sub> <math>\longrightarrow</math> (CH<sub>2</sub>O) + 5H<sub>2</sub>O |
6H<sub>2</sub> + 2O<sub>2</sub> + CO<sub>2</sub> <math>\longrightarrow</math> (CH<sub>2</sub>O) + 5H<sub>2</sub>O |
||
In particular, a recent study carried out on ''[[Alcaligenes eutrophus|Alcaligenes eutropha]]'', one of the most representative species of Knallgas bacteria, highlighted that at low concentrations of O<sub>2</sub> (about 10 mol %) and consequently with a low ΔH<sub>2</sub>/ΔCO<sub>2</sub> molar ratio (3.3), the energy efficiency of Co2 fixation increasing until of 50%.This is an interesting characteristic of these microorganisms because once assimilated, the carbon dioxide is reduced to [[polyhydroxybutyrate]] , from which its derivatives, being '''biodegradable''', are used in various eco-sustainable applications.<ref>{{ |
In particular, a recent study carried out on ''[[Alcaligenes eutrophus|Alcaligenes eutropha]]'', one of the most representative species of Knallgas bacteria, highlighted that at low concentrations of O<sub>2</sub> (about 10 mol %) and consequently with a low ΔH<sub>2</sub>/ΔCO<sub>2</sub> molar ratio (3.3), the energy efficiency of Co2 fixation increasing until of 50%.This is an interesting characteristic of these microorganisms because once assimilated, the carbon dioxide is reduced to [[polyhydroxybutyrate]] , from which its derivatives, being '''biodegradable''', are used in various eco-sustainable applications.<ref>{{cite journal|last=Yu|first=Jian|last2=Dow|first2=Allexa|last3=Pingali|first3=Sricanth| name-list-format = vanc |date=2013-07-17|title=The energy efficiency of carbon dioxide fixation by a hydrogen-oxidizing bacterium|journal=International Journal of Hydrogen Energy|volume=38|issue=21|pages=8683–8690|doi=10.1016/j.ijhydene.2013.04.153|issn=0360-3199}}</ref><ref>{{cite journal|last=Ishizaki|first=Ayaaki|last2=Tanaka|first2=Kenji| name-list-format = vanc |date=1990-01-01|title=Batch culture of Alcaligenes eutrophus ATCC 17697T using recycled gas closed circuit culture system|journal=Journal of Fermentation and Bioengineering|volume=69|issue=3|pages=170–174|doi=10.1016/0922-338X(90)90041-T|issn=0922-338X}}</ref> |
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==References== |
== References == |
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{{Reflist}} |
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Revision as of 14:11, 23 December 2019
 | This article needs additional citations for verification. (April 2015) |
Hydrogen oxidizing bacteria are a group of facultative autotrophs that can use hydrogen as electron donor.
They can be divided into aerobics and anaerobics. The former use hydrogen as an electron donor and oxygen as an acceptor while the latter use sulphate or nitrogen dioxide as electron acceptors.[1] Some species of both bacteria types have been isolated in different environments, for example in fresh waters, sediments, soils, activated sludge, hot springs, hydrothermal vents and percolating water [2].
These organisms are able to exploit the special properties of molecular hydrogen (for instance redox potential and diffusion coefficient) thanks to the presence of hydrogenases [3]. The aerobic hydrogen oxidizing bacteria are facultative autotrophs, but they can also have mixotrophic or completely heterotrophic growth. Most of them show greater growth on organic substrates.The use of hydrogen as an electron donor coupled with the ability to synthesize organic mutter, through the reductive assimilation of CO2, characterize the hydrogen oxidizing bacteria. Among the most represented genres of these organisms we find: Caminibacter, Aquifex, Ralstonia and Paracoccus.
Hydrogen production and its distribution in the oceans
The most widespread compound on our Earth is hydrogen, which represents around three-quarters of all the elements.[4] In the atmosphere, its concentration is about 0.5-0.6 ppm and so here it represents the most abundant trace gas, after methane.[5] Therefore, H2 can be used as energy source in several biological processes, also because it has a highly negative redox potential (E0’= -0.414 V) . It can be coupled with different compounds:
- O2: the oxic respiration is performed (H2+1/2O2 → H2O)
- Oxidized compounds, such as carbon dioxide or sulfate. [6]
In the ecosystems, hydrogen can be produced through biological and abiotic processes .
The abiotic processes are mainly due to geothermal production [7] and serpentinization [8]. In the first case, hydrogen is usually present as a gas and probably can be obtained by different reactions:
1. Water may react with silicon radical at high temperature:
Si· + H2O → SiOH + H·
H· + H· → H2
2. The proposed reaction between iron oxides and water, at temperatures higher than 800°C:
2FeO + H2O → Fe2O3 + H2
2Fe3O4 + H2O → 3Fe2O3 + H2 [7]
On the other hand, serpentinization is an exothermic geochemical mechanism that occurs when, thanks to the tectonic movements, the ultramafic rocks raise and reach the water. This process can bring to the production of large quantities of H2, but also of methane and organic substances. [8]
The main mechanisms that lead to the formation of hydrogen, involving different microorganisms, are nitrogen fixation and fermentation. The first one happens in some bacteria, such as heterocystous and non-heterocystous cyanobacteria, that have a specialized enzyme, the nitrogenase, which catalizes the reduction of N2 to NH4+. In addition, these microorganisms have another enzyme, the hydrogenase, that oxidizes the H2 released as a by-product. [4] Therefore, in this type of bacteria, the amount of hydrogen produced depends on the ratio between H2 production and consumption.[9] In some cases, the H2 can be present in the environments because the N2-fixing bacteria can have a low quantity of hydrogenases. [10][9] Instead, fermentation is performed by some strict or facultative anaerobic heterotrophic bacteria, in particular Clostridia [11] ,that degrade organic molecules, producing hydrogen as one of the products. Therefore, this type of metabolism mainly occurs in anoxic sites, such as lake sediments, deep-sea hydrothermal vents and human gut. [12]
Probably mainly due to the biotic processes, in the marine habitats it was observed that the concentrations of hydrogen were supersaturated. In all these environments, the highest concentrations were in the first metres, decreasing to the thermocline and reaching the lowest concentrations in the deep oceans. [5] Globally, tropical and subtropical oceans appear to have the most abundant quantity of H2 [13][5][14], while the least amount is present in higher latitudes [5][15][16]. However, it was observed that the realease of hydrogen in the oceans is dependent on the solar radiation, showing a daily change with the maximum peak at noon [5][13][14]. Nitrogen fixation, performed by cyanobacteria, leads to the production of one molecule of H2 at least. This metabolism is thought to be the major one involved in the increase of H2 in the oceans .[5] Despite there are some evidences of this,[17][18] more data need to be collected to finally correlate the two phenomena.
Hydrogen oxidizing bacteria in Hydrothermal vents
H2 is an important electron donor in a particular environment: Hydrothermal vents. In this environment hydrogen oxidation represents a significant origin of energy, sufficient to conduct ATP synthesis and autotrophic CO2 fixation so hydrogen oxidizing bacteria are relevant in deep sea habitats. Among the main chemosynthetic reactions that take place in hydrothermal vents, the oxidation of the sulphide and the hydrogen one covers a central role. In particular, for autotrophic carbon fixation, hydrogen oxidation metabolism is more favored than the sulfide/thiosulfate oxidation, although less energy is released (only -237 kJ/mol compared to – 797 kJ/mol)[19]. To fix a mole of carbon during the hydrogen oxidation, one third of the energy necessary for the sulphide oxidation is used. This is due to the redox potential of hydrogen, which is more negative than NAD (P)/H. Based on the amount of sulphide, hydrogen and other farm biotics, this phenomenon can be intensified leading, in some cases, to an energy production by oxidation of the hydrogen of 10 -18 times higher than produced one by the sulphide oxidation [20][21] .
Knallgas-bacteria
Aerobic Hydrogen oxidizing bacteria, or sometimes Knallgas-bacteria, are bacteria that oxidize hydrogen as a source of energy with oxygen as final electron acceptor. See microbial metabolism (hydrogen oxidation). These bacteria include Hydrogenobacter thermophilus, Cupriavidus necator, Hydrogenovibrio marinus, and Helicobacter pylori.[22] There are both Gram positive and Gram negative knallgas bacteria.
Most grow best under microaerobic conditions. They do this because the hydrogenase enzyme used in hydrogen oxidation is inhibited by the presence of oxygen, but oxygen is still needed as a terminal electron acceptor.[23]
The word Knallgas means "oxyhydrogen" (a mixture of hydrogen and oxygen, literally "bang-gas") in Germanic languages.
Strain MH-110
Ocean’s surface water is characterised by a high concentration of hydrogen [24]. In 1989, for the first time, an aerobic hydrogen oxidizing bacteria was isolated from sea water and the discovery of this strain was very important also because for the first time a hydrogen oxidizing bacteria was identified in normal temperature condition. Experimentally it has been shown that the MH-110 strain is able to grow in an atmosphere (under a continuous gas flow system) characterized by an oxygen concentration of 40% (analogue characteristics are present in the surface water from which the bacteria were isolated which is, in fact, a fairly aerated region). This differs from the usual behaviour of hydrogen oxidizing bacteria which in general thrive strictly under microaerophilic conditions (<10% O2).[25][26]
This strain is also capable to couple the Hydrogen oxidation with the reduction of sulfur compounds such as thiosulfate and tetrathionate.
Knallgas bacteria : metabolism
The aerobic hydrogen oxidizing bacteria, more known as Knallgas bacteria, are a group of bacteria which are able to fix carbon dioxide using H2 as electron donor and energy source and O2 as terminal electron acceptor. Actually, Knallgas bacteria stand out from the hydrogen oxydizing bacteria which, although using H2 as an electron donor, are not able to fix CO2, as Knallgas do. [27]
This aerobic hydrogen oxidation, also known as the Knallgas reaction, which releases a considerable amount of energy, determines the formation of proton motive force (PMF).
H2 + O2 H2O ΔG0 = -237 Kj
The key enzymes involved in this reaction are the hydrogenase which lead the electrons through the electron transport chain, from hydrogen to the final acceptor, that is O2 which is actually reduced in water, the only by-product.[28] The hydrogenases that are divided into three categories according to the type of metal present in the active site, are the enzymes that allow the oxidation of hydrogen. The first evidence of the presence of these enzymes has been found for the first time in Pseudomonas saccharophila, Alcaligenes ruhlandii and Alcaligenese eutrophus in which there were two types of hydrogenases: cytoplasmatic and membrane-bound. If the first enzyme takes up hydrogen and reduce the NAD+ in NADH for carbon fixation, the second is involved in the generation of the proton motive force. [29][30] Anyway, in most of the knallgas bacteria only one type of hydrogensase was observed, the one bound to the membrane that provided hydrogen activation.[31]
These microorganisms are also defined as facultative authotrophs, neverthless some of them are also able to live in completly heterotrophic conditions using organic substances as electron donor and energy source, even if in this case the hydrogenase activity takes on less importance or is completely absent.[32]
However, Knallgas bacteria, growing as chemolithoautotrophs, as soon as they integrate every molecule of Co2, they can produce, through the Calvin Benson Cycle or reverse citric acid cycle (TCA cycle), biomolecules necessary for the cell.[33][34]
6H2 + 2O2 + CO2 (CH2O) + 5H2O
In particular, a recent study carried out on Alcaligenes eutropha, one of the most representative species of Knallgas bacteria, highlighted that at low concentrations of O2 (about 10 mol %) and consequently with a low ΔH2/ΔCO2 molar ratio (3.3), the energy efficiency of Co2 fixation increasing until of 50%.This is an interesting characteristic of these microorganisms because once assimilated, the carbon dioxide is reduced to polyhydroxybutyrate , from which its derivatives, being biodegradable, are used in various eco-sustainable applications.[35][36]
References
- ^ Aragno, Michel; Schlegel, Hans G. (1981). "The Hydrogen-Oxidizing Bacteria". In Starr, Mortimer P.; Stolp, Heinz; Trüper, Hans G.; Balows, Albert (eds.). The Prokaryotes: A Handbook on Habitats, Isolation, and Identification of Bacteria. Springer Berlin Heidelberg. pp. 865–893. doi:10.1007/978-3-662-13187-9_70. ISBN 978-3-662-13187-9.
{{cite book}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Koskinen PE, Beck SR, Orlygsson J, Puhakka JA (November 2008). "Ethanol and hydrogen production by two thermophilic, anaerobic bacteria isolated from Icelandic geothermal areas". Biotechnology and Bioengineering. 101 (4): 679–90. doi:10.1002/bit.21942. PMID 18500766.
- ^ Barz M, Beimgraben C, Staller T, Germer F, Opitz F, Marquardt C, et al. (November 2010). "Distribution analysis of hydrogenases in surface waters of marine and freshwater environments". PloS One. 5 (11): e13846. Bibcode:2010PLoSO...513846B. doi:10.1371/journal.pone.0013846. PMID 21079771.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b Das D, Veziroǧlu TN (2001-01-01). "Hydrogen production by biological processes: a survey of literature". International Journal of Hydrogen Energy. 26 (1): 13–28. doi:10.1016/S0360-3199(00)00058-6. ISSN 0360-3199.
- ^ a b c d e f Barz M, Beimgraben C, Staller T, Germer F, Opitz F, Marquardt C, et al. (November 2010). "Distribution analysis of hydrogenases in surface waters of marine and freshwater environments". PloS One. 5 (11): e13846. Bibcode:2010PLoSO...513846B. doi:10.1371/journal.pone.0013846. PMID 21079771.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Heimann A, Jakobsen R, Blodau C (January 2010). "Energetic constraints on H2-dependent terminal electron accepting processes in anoxic environments: a review of observations and model approaches". Environmental Science & Technology. 44 (1): 24–33. Bibcode:2010EnST...44...24H. doi:10.1021/es9018207. PMID 20039730.
- ^ a b Aragno, Michel (1992). "Thermophilic, Aerobic, Hydrogen-Oxidizing (Knallgas) Bacteria". In Balows, Albert; Trüper, Hans G.; Dworkin, Martin; Harder, Wim (eds.). The Prokaryotes. Springer New York. pp. 3917–3933. doi:10.1007/978-1-4757-2191-1_55. ISBN 978-1-4757-2191-1.
{{cite book}}:|work=ignored (help); Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ a b Brazelton WJ, Nelson B, Schrenk MO (2012). "Metagenomic evidence for h(2) oxidation and h(2) production by serpentinite-hosted subsurface microbial communities". Frontiers in Microbiology. 2: 268. doi:10.3389/fmicb.2011.00268. PMC 3252642. PMID 22232619.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b Tiwari, Archana; Pandey, Anjana (January 2012). "Cyanobacterial hydrogen production – A step towards clean environment". International Journal of Hydrogen Energy. 3 7 (1): 139–150. doi:10.1016/j.ijhydene.2011.09.100.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Pumphrey GM, Ranchou-Peyruse A, Spain JC (July 2011). "Cultivation-independent detection of autotrophic hydrogen-oxidizing bacteria by DNA stable-isotope probing". Applied and Environmental Microbiology. 77 (14): 4931–8. doi:10.1128/aem.00285-11. PMID 21622787.
- ^ Adams MW, Stiefel EI (December 1998). "Biological hydrogen production: not so elementary". Science. 282 (5395): 1842–3. doi:10.1126/science.282.5395.1842. PMID 9874636.
- ^ Adam N, Perner M (2018). "Microbially Mediated Hydrogen Cycling in Deep-Sea Hydrothermal Vents". Frontiers in Microbiology. 9: 2873. doi:10.3389/fmicb.2018.02873. PMC 6265342. PMID 30532749.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b Herr, Frank L.; Frank, Ernest C.; Leone, Gerald M.; Kennicutt, Mahlon C. (January 1984). "Diurnal variability of dissolved molecular hydrogen in the tropical South Atlantic Ocean". Deep Sea Research Part A. Oceanographic Research Papers. 31 (1): 13–20. Bibcode:1984DSRA...31...13H. doi:10.1016/0198-0149(84)90069-4. ISSN 0198-0149.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ a b Conrad, Ralf; Seiler, Wolfgang (December 1988). "Methane and hydrogen in seawater (Atlantic Ocean)". Deep Sea Research Part A. Oceanographic Research Papers. 35 (12): 1903–1917. Bibcode:1988DSRA...35.1903C. doi:10.1016/0198-0149(88)90116-1. ISSN 0198-0149.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Herr, Frank L.; Scranton, Mary I.; Barger, William R. (September 1981). "Dissolved hydrogen in the Norwegian Sea: Mesoscale surface variability and deep-water distribution". Deep Sea Research Part A. Oceanographic Research Papers. 28 (9): 1001–1016. Bibcode:1981DSRA...28.1001H. doi:10.1016/0198-0149(81)90014-5. ISSN 0198-0149.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Punshon, Stephen; Moore, Robert M.; Xie, Huixiang (April 2007). "Net loss rates and distribution of molecular hydrogen (H2) in mid-latitude coastal waters". Marine Chemistry. 105 (1–2): 129–139. doi:10.1016/j.marchem.2007.01.009. ISSN 0304-4203.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Lindberg P, Lindblad P, Cournac L (April 2004). "Gas exchange in the filamentous cyanobacterium Nostoc punctiforme strain ATCC 29133 and Its hydrogenase-deficient mutant strain NHM5". Applied and Environmental Microbiology. 70 (4): 2137–45. doi:10.1128/aem.70.4.2137-2145.2004. PMID 15066806.
- ^ Wilson ST, Foster RA, Zehr JP, Karl DM (2010-04-08). "Hydrogen production by Trichodesmium erythraeum Cyanothece sp. and Crocosphaera watsonii". Aquatic Microbial Ecology. 59: 197–206. doi:10.3354/ame01407.
- ^ Adam N, Perner M (2018-11-23). "Microbially Mediated Hydrogen Cycling in Deep-Sea Hydrothermal Vents". Frontiers in Microbiology. 9: 2873. doi:10.3389/fmicb.2018.02873. PMID 30532749.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Anantharaman K, Breier JA, Sheik CS, Dick GJ (January 2013). "Evidence for hydrogen oxidation and metabolic plasticity in widespread deep-sea sulfur-oxidizing bacteria". Proceedings of the National Academy of Sciences of the United States of America. 110 (1): 330–5. doi:10.1073/pnas.1215340110. PMID 23263870.
- ^ M. Petersen, Jillian U. Zielinski, Frank Pape, Thomas Seifert, Richard Moraru, Cristina Amann, Rudolf Hourdez, Stephane R. Girguis, Peter D. Wankel, Scott Barbe, Valerie Pelletier, Eric Fink, Dennis Borowski, Christian Bach, Wolfgang Nicole, Dubilier. Hydrogen is an energy source for hydrothermal vent symbioses. OCLC 866919946.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Olson JW and Maier RJ (2002) Molecular hydrogen as an energy source for Helicobacter pylori. Science 298:1788-90. full text
- ^ Jugder, Bat-Erdene; Welch, Jeffrey; Aguey-Zinsou, Kondo-Francois; Marquis, Christopher P. (2013). "Fundamentals and electrochemical applications of [Ni–Fe]-uptake hydrogenases". RSC Advances. 3 (22): 8142. doi:10.1039/c3ra22668a. ISSN 2046-2069.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Conrad, Ralf; Seiler, Wolfgang (11 July 1988). "Methane and hydrogen in seawater (Atlantic Ocean)". Deep Sea Research Part A. Oceanographic Research Papers. 35 (12): 1903–1917. Bibcode:1988DSRA...35.1903C. doi:10.1016/0198-0149(88)90116-1.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Nishihara, Hirofumi; Igarashi, Yasuo; Kodama, Tohru (1989-06-01). "Isolation of an obligately chemolithoautotrophic, halophilic and aerobic hydrogen-oxidizing bacterium from marine environment". Archives of Microbiology. 152 (1): 39–43. doi:10.1007/BF00447009. ISSN 1432-072X.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Nishihara, Hirofumi; Igabashi, Yasuo; Kodama, Tohruy (1991). "Hydrogenovibrio marinus gen. nov., sp. nov., a Marine Obligately Chemolithoautotrophic Hydrogen-Oxidizing Bacterium". International Journal of Systematic and Evolutionary Microbiology. 41 (1): 130–133. doi:10.1099/00207713-41-1-130. ISSN 1466-5026.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Vésteinsdòttir, Hildur (2008). "Physiological and phylogenetic studies of thermophilic, hydrogen and sulfur oxidizing bacteria isolated from Icelandic geothermal areas" (PDF).
{{cite web}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help)CS1 maint: url-status (link) - ^ Bowien B, Schlegel HG (1981-10-01). "Physiology and biochemistry of aerobic hydrogen-oxidizing bacteria". Annual Review of Microbiology. 35 (1): 405–52. doi:10.1146/annurev.mi.35.100181.002201. PMID 6271040.
- ^ Schink B, Schlegel HG (1978-06-13). "Hydrogen metabolism in aerobic hydrogen-oxidizing bacteria". Biochimie. 60 (3): 297–305. doi:10.1016/S0300-9084(78)80826-8. PMID 667183.
- ^ Appel, Jens; Schulz, Rüdiger (1998-11-01). "Hydrogen metabolism in organisms with oxygenic photosynthesis: hydrogenases as important regulatory devices for a proper redox poising?". Journal of Photochemistry and Photobiology B: Biology. 47 (1): 1–11. doi:10.1016/S1011-1344(98)00179-1. ISSN 1011-1344.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Schneider K, Schlegel HG (April 1977). "Localization and stability of hydrogenases from aerobic hydrogen bacteria". Archives of Microbiology. 112 (3): 229–38. doi:10.1007/BF00413086. PMID 871226.
- ^ Aragno, Michel; Schlegel, Hans G. (1981). "The Hydrogen-Oxidizing Bacteria". In Starr, Mortimer P.; Stolp, Heinz; Trüper, Hans G.; Balows, Albert (eds.). The Prokaryotes: A Handbook on Habitats, Isolation, and Identification of Bacteria. Springer Berlin Heidelberg. pp. 865–893. doi:10.1007/978-3-662-13187-9_70. ISBN 978-3-662-13187-9.
{{cite book}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help) - ^ Schlegel HG, Eberhardt U (1972-01-01). "Regulatory Phenomena in the Metabolism of Knallgasbacteria". In Rose AH, Tempest DW (eds.). Advances in Microbial Physiology Volume 7. Advances in Microbial Physiology. Vol. 7. Academic Press. pp. 205–242. doi:10.1016/s0065-2911(08)60079-x. ISBN 9780120277070.
- ^ Madigan, Michael T.; Martinko, John M; Parker, Jack; Brock, Thomas D. (2003). Brock, biology of microorganisms (10th ed ed.). Upper Saddle River, N.J Prentice Hall. ISBN 978-0-13-049147-3.
{{cite book}}:|edition=has extra text (help); Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help)CS1 maint: date and year (link) - ^ Yu, Jian; Dow, Allexa; Pingali, Sricanth (2013-07-17). "The energy efficiency of carbon dioxide fixation by a hydrogen-oxidizing bacterium". International Journal of Hydrogen Energy. 38 (21): 8683–8690. doi:10.1016/j.ijhydene.2013.04.153. ISSN 0360-3199.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help); no-break space character in|title=at position 52 (help) - ^ Ishizaki, Ayaaki; Tanaka, Kenji (1990-01-01). "Batch culture of Alcaligenes eutrophus ATCC 17697T using recycled gas closed circuit culture system". Journal of Fermentation and Bioengineering. 69 (3): 170–174. doi:10.1016/0922-338X(90)90041-T. ISSN 0922-338X.
{{cite journal}}: Unknown parameter|name-list-format=ignored (|name-list-style=suggested) (help)
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