Thioploca: Difference between revisions
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== Metabolism == |
== Metabolism == |
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This particular genus shows interesting and not completely clarified [[Metabolic pathway|metabolic pathways]]. This not |
This particular genus shows interesting and not completely clarified [[Metabolic pathway|metabolic pathways]]. This not well-known situation is due to the absence of no pure culture, but they seem to be [[Mixotroph|mixotrophic]] [[Sulphide oxidizer|sulphide oxidizers]]. Data in our hands are mainly recovered by several experiments conducted on entire communities or bundles of filaments.<ref name=":0">{{Citation|last=Jørgensen|first=Bo Barker|title=Thioploca|date=2015|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/9781118960608.gbm01227|work=Bergey's Manual of Systematics of Archaea and Bacteria|pages=1–12|publisher=John Wiley & Sons, Ltd|language=en|doi=10.1002/9781118960608.gbm01227|isbn=978-1-118-96060-8|access-date=2021-12-23|last2=Teske|first2=Andreas|last3=Ahmad|first3=Azeem}}</ref> The hypothesis suggested by research of the possible nature of [[Methylotroph|methylotrophs]] organisms was rejected, mainly because the areas in which they were found are not very rich in [[methane]].<ref name=":1">{{Cite journal|last=Jørgensen|first=Bo Barker|last2=Gallardo|first2=Victor A|date=1999-04-01|title=Thioploca spp.: filamentous sulfur bacteria with nitrate vacuoles|url=https://doi.org/10.1111/j.1574-6941.1999.tb00585.x|journal=FEMS Microbiology Ecology|volume=28|issue=4|pages=301–313|doi=10.1111/j.1574-6941.1999.tb00585.x|issn=0168-6496}}</ref> Therefore, the small amount of methane concentration allows rejecting the possibilities of use of it for metabolic activity of a large population of these microorganisms.<ref>{{Cite journal|last=Ferdelman|first=Timothy G.|last2=Lee|first2=Cindy|last3=Pantoja|first3=Silvio|last4=Harder|first4=Jens|last5=Bebout|first5=Brad M.|last6=Fossing|first6=Henrik|date=1997– August|title=Sulfate reduction and methanogenesis in a Thioploca-dominated sediment off the coast of Chile|url=http://dx.doi.org/10.1016/s0016-7037(97)00158-0|journal=Geochimica et Cosmochimica Acta|volume=61|issue=15|pages=3065–3079|doi=10.1016/s0016-7037(97)00158-0|issn=0016-7037}}</ref> More specific research has shown that, through the use of 14C-labeled, they do not incorporate this specific compound or [[methanol]]. On the other hand, they showed incorporation capacity [[Carbon dioxide|CO<sub>2</sub>]] and different substrates ([[acetate]], [[Amino acid|amino acids]], [[bicarbonate]], [[glucose]], [[glycine]], etc). For this reason, these microorganisms are considered a very good example of [[mixotrophic bacteria]].<ref>{{Cite journal|last=Maier|first=Siegfried|last2=Gallardo|first2=Victor A.|date=1984-10|title=Nutritional characteristics of two marine thioplocas determined by autoradiography|url=http://dx.doi.org/10.1007/bf00402003|journal=Archives of Microbiology|volume=139-139|issue=2-3|pages=218–220|doi=10.1007/bf00402003|issn=0302-8933}}</ref> <ref name=":2">{{Cite journal|last=Høgslund|first=Signe|last2=Revsbech|first2=Niels Peter|last3=Kuenen|first3=J. Gijs|last4=Jørgensen|first4=Bo Barker|last5=Gallardo|first5=Victor Ariel|last6=Vossenberg|first6=Jack van de|last7=Nielsen|first7=Jeppe Lund|last8=Holmkvist|first8=Lars|last9=Arning|first9=Esther T.|last10=Nielsen|first10=Lars Peter|date=2009-06|title=Physiology and behaviour of marine Thioploca|url=https://www.nature.com/articles/ismej200917|journal=The ISME Journal|language=en|volume=3|issue=6|pages=647–657|doi=10.1038/ismej.2009.17|issn=1751-7370}}</ref>Their basic strategy is based on the presence of trichomes, aggregates in bundles surrounded by a sheath, even if sometimes they are found as free-living trichomes. They are basically defined as [[Sulfate-reducing microorganism|sulphur bacteria]], capable of oxidizing mainly H<sub>2</sub>S ([[Hydrogen sulfide|Hydrogen sulphide]], etc.) and accumulating NO<sub>3</sub> ([[Nitrate]]) in a specific vacuole in their cells.<ref name=":0" /> <ref name=":2" />In the vacuole the concentrations of nitrate can increase up to 0.5 M. <ref>{{Cite journal|last=Fossing|first=H.|last2=Gallardo|first2=V. A.|last3=Jørgensen|first3=B. B.|last4=Hüttel|first4=M.|last5=Nielsen|first5=L. P.|last6=Schulz|first6=H.|last7=Canfield|first7=D. E.|last8=Forster|first8=S.|last9=Glud|first9=R. N.|last10=Gundersen|first10=J. K.|last11=Küver|first11=J.|date=1995-04|title=Concentration and transport of nitrate by the mat-forming sulphur bacterium Thioploca|url=https://www.nature.com/articles/374713a0|journal=Nature|language=en|volume=374|issue=6524|pages=713–715|doi=10.1038/374713a0|issn=1476-4687}}</ref>They have also shown the capacity to accumulate S<sub>0</sub> (elemental sulphur) in the cells under the forms of drops, as a result of oxidation of hydrogen sulphide. These bacteria have developed this system (with morphological, physiological, and metabolic adaptation) to maintain a metabolism based on a different source of [[electron donor]] and [[Electron acceptor|acceptor]], which are situated in a different zone in the [[water column]] and characterized by a different gradient. <ref name=":2" /> |
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=== Oxygen uptake and resistance === |
=== Oxygen uptake and resistance === |
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These genera show a behavior typical of [[Microaerophile|microaerophilic]] microorganisms. Data based on behavior and oxygen uptake experiment has confirmed their nature. They show an uptake rate of oxygen of 1760 µmol dm-3 h-1.<ref name=":2" /> |
These genera show a behavior typical of [[Microaerophile|microaerophilic]] microorganisms. Data based on behavior and oxygen uptake experiment has confirmed their nature. They show an uptake rate of oxygen of 1760 µmol dm<sup>-3</sup> h<sup>-1</sup>.<ref name=":2" /> Even if they show an uptake rate similar to ''[[Thiomargarita|Thiomargarita spp.]]'', they do not have the same capacities to resist for a longer time in presence of oxygen.<ref>{{Cite journal|last=Schulz|first=Heide N.|last2=de Beer|first2=Dirk|date=2002-11|title=Uptake Rates of Oxygen and Sulfide Measured with Individual Thiomargarita namibiensis Cells by Using Microelectrodes|url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC129903/|journal=Applied and Environmental Microbiology|volume=68|issue=11|pages=5746–5749|doi=10.1128/AEM.68.11.5746-5749.2002|issn=0099-2240|pmid=12406774}}</ref> For this reason, they populate OMZs ([[Oxygen minimum zone|Oxygen Minimum Zone]]). <ref name=":2" /> |
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=== |
=== Sulphur metabolism === |
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''Thioploca spp.'' has shown two types of response to sulphide based on its concentrations of it. |
''Thioploca spp.'' has shown two types of response to sulphide based on its concentrations of it. They have a positive response to low sulphide (<100 µM) concentrations and negative to high concentrations.<ref name=":1" /> <ref name=":0" />They show a maximum uptake rate at 200 µM.<ref name=":2" /> This coupled with [[taxis]] towards nitrate, regulates the behavior of this genus. Also involved in it is the gradient of O<sub>2</sub> affecting it in a minor way. For this reason, these microorganisms are defined as microaerophilic. Hypothetically they could be in competition with other sulphide oxidizing bacteria, but with the ability to accumulate nitrate they create a perfect strategy to access both electron donor and acceptor at the same moment. <ref>{{Cite journal|last=Nelson|first=Douglas C.|last2=Jørgensen|first2=Bo Barker|last3=Revsbech|first3=Niels Peter|date=1986-08|title=Growth Pattern and Yield of a Chemoautotrophic |
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Beggiatoa |
Beggiatoa |
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sp. in Oxygen-Sulfide Microgradients|url=http://dx.doi.org/10.1128/aem.52.2.225-233.1986|journal=Applied and Environmental Microbiology|volume=52|issue=2|pages=225–233|doi=10.1128/aem.52.2.225-233.1986|issn=0099-2240}}</ref><ref name=":1" /> |
sp. in Oxygen-Sulfide Microgradients|url=http://dx.doi.org/10.1128/aem.52.2.225-233.1986|journal=Applied and Environmental Microbiology|volume=52|issue=2|pages=225–233|doi=10.1128/aem.52.2.225-233.1986|issn=0099-2240}}</ref><ref name=":1" /> |
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Based on some research, we know that oxidized iron is important in process of scavenging H<sub>2</sub>S (hydrogen sulphide), |
Based on some research, we know that oxidized iron is important in process of scavenging H<sub>2</sub>S (hydrogen sulphide), although the precise mechanism is unknown. <ref>{{Cite journal|last=Thamdrup|first=Bo|last2=Canfield|first2=Donald E.|date=1996|title=Pathways of carbon oxidation in continental margin sediments off central Chile|url=https://onlinelibrary.wiley.com/doi/abs/10.4319/lo.1996.41.8.1629|journal=Limnology and Oceanography|language=en|volume=41|issue=8|pages=1629–1650|doi=10.4319/lo.1996.41.8.1629|issn=1939-5590}}</ref>At the same time, the inhabited sheaths of ''Thioploca'' can be covered by filamentous sulphate-reducing bacteria. These sulphate-reducing bacteria, pertaining to the genus ''[[Desulfonema]]'', could explain the high rate of recycling of H<sub>2</sub>S and its availability also in sulphide-pore environments. <ref name=":1" /> |
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Furthermore, the elemental sulphur accumulated in the cells as drops is involved in sulphur metabolism. This reaction is also involved oxygen which oxidates the elemental sulphur: |
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'''2S<sub>0</sub>+3O<sub>2</sub>+ 2H<sub>2</sub>O → 4SO<sub>4</sub><sup>2-</sup>+ 4H<sup>+</sup>''' |
'''2S<sub>0</sub>+3O<sub>2</sub>+ 2H<sub>2</sub>O → 4SO<sub>4</sub><sup>2-</sup>+ 4H<sup>+</sup>''' |
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Another reaction |
Another reaction, involving nitrate, is part of the oxidation: |
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'''4S<sub>0</sub>+3NO<sub>3</sub><sup>-</sup>+ 7H<sub>2</sub>O → 4SO<sub>4</sub><sup>2-</sup>+ 3NH<sub>4</sub><sup>+</sup>+2H<sup>+</sup>''' |
'''4S<sub>0</sub>+3NO<sub>3</sub><sup>-</sup>+ 7H<sub>2</sub>O → 4SO<sub>4</sub><sup>2-</sup>+ 3NH<sub>4</sub><sup>+</sup>+2H<sup>+</sup>''' |
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=== Nitrogen metabolism === |
=== Nitrogen metabolism === |
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''Thioploca'' genus has shown also the capacity to accumulate nitrate and use the [[Dissimilatory nitrate reduction to ammonium]] (DNRA) pathway.<ref name=":3">{{Cite journal|last=Otte|first=null|last2=Kuenen|first2=null|last3=Nielsen|first3=null|last4=Paerl|first4=null|last5=Zopfi|first5=null|last6=Schulz|first6=null|last7=Teske|first7=null|last8=Strotmann|first8=null|last9=Gallardo|first9=null|last10=Jorgensen|first10=null|date=1999-07|title=Nitrogen, carbon, and sulfur metabolism in natural thioploca samples|url=https://pubmed.ncbi.nlm.nih.gov/10388716/|journal=Applied and Environmental Microbiology|volume=65|issue=7|pages=3148–3157|doi=10.1128/AEM.65.7.3148-3157.1999|issn=1098-5336|pmid=10388716}}</ref><ref name=":2" /><ref name=":0" /><ref name=":1" /> To obtain nitrate they perform |
''Thioploca'' genus has shown also the capacity to accumulate nitrate and use the [[Dissimilatory nitrate reduction to ammonium]] (DNRA) pathway.<ref name=":3">{{Cite journal|last=Otte|first=null|last2=Kuenen|first2=null|last3=Nielsen|first3=null|last4=Paerl|first4=null|last5=Zopfi|first5=null|last6=Schulz|first6=null|last7=Teske|first7=null|last8=Strotmann|first8=null|last9=Gallardo|first9=null|last10=Jorgensen|first10=null|date=1999-07|title=Nitrogen, carbon, and sulfur metabolism in natural thioploca samples|url=https://pubmed.ncbi.nlm.nih.gov/10388716/|journal=Applied and Environmental Microbiology|volume=65|issue=7|pages=3148–3157|doi=10.1128/AEM.65.7.3148-3157.1999|issn=1098-5336|pmid=10388716}}</ref><ref name=":2" /><ref name=":0" /><ref name=":1" /> To obtain nitrate they perform a vertical migration. Sheats of ''Thioploca spp''. are considered a compatible niche for the growth of [[Anammox|anammox bacteria]], due to the ability of ''Thioploca spp.'' to perform Dissimilative nitrate reduction to ammonium. <ref name=":2" />They are able to perform [[Nitrile reduction|nitrite reduction]] and show positive taxis towards nitrite. <ref name=":3" />The dissimilatory nitrate reduction is involved also in the oxidation of sulphide that leads to a higher accumulation of elemental sulphur. A higher presence and reduction of nitrate increase drastically the fixation of carbon dioxide (CO<sub>2</sub>). In any case, nitrate uptake can occur also in low environmental concentrations. <ref name=":2" /> |
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==Species== |
==Species== |
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Revision as of 11:32, 27 December 2021
| Thioploca | |
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| Scientific classification | |
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| Phylum: | |
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| Genus: | Thioploca Lauterborn, 1907[2]
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Thioploca is a genus of filamentous sulfur bacteria which occurs along 3,000 kilometres (1,900 mi) of coast off the west of South America. A large vacuole occupies more than 80% of their cell volume and contains sulfide and nitrate which they use to make energy for their metabolism by oxidising sulfide with nitrate. The concentration of nitrate in the vacuole is extremely high (500 mM) even though the sediments in which they live are relatively very low in nitrogen (25 μM).[3] Because they use both sulfur and nitrogen compounds they may provide an important link between the nitrogen and sulfur cycles. They secrete a sheath of mucus which they use as a tunnel to travel between the sulfide containing sediment and the nitrate containing sea water.[4]
Metabolism
This particular genus shows interesting and not completely clarified metabolic pathways. This not well-known situation is due to the absence of no pure culture, but they seem to be mixotrophic sulphide oxidizers. Data in our hands are mainly recovered by several experiments conducted on entire communities or bundles of filaments.[5] The hypothesis suggested by research of the possible nature of methylotrophs organisms was rejected, mainly because the areas in which they were found are not very rich in methane.[6] Therefore, the small amount of methane concentration allows rejecting the possibilities of use of it for metabolic activity of a large population of these microorganisms.[7] More specific research has shown that, through the use of 14C-labeled, they do not incorporate this specific compound or methanol. On the other hand, they showed incorporation capacity CO2 and different substrates (acetate, amino acids, bicarbonate, glucose, glycine, etc). For this reason, these microorganisms are considered a very good example of mixotrophic bacteria.[8] [9]Their basic strategy is based on the presence of trichomes, aggregates in bundles surrounded by a sheath, even if sometimes they are found as free-living trichomes. They are basically defined as sulphur bacteria, capable of oxidizing mainly H2S (Hydrogen sulphide, etc.) and accumulating NO3 (Nitrate) in a specific vacuole in their cells.[5] [9]In the vacuole the concentrations of nitrate can increase up to 0.5 M. [10]They have also shown the capacity to accumulate S0 (elemental sulphur) in the cells under the forms of drops, as a result of oxidation of hydrogen sulphide. These bacteria have developed this system (with morphological, physiological, and metabolic adaptation) to maintain a metabolism based on a different source of electron donor and acceptor, which are situated in a different zone in the water column and characterized by a different gradient. [9]
Oxygen uptake and resistance
These genera show a behavior typical of microaerophilic microorganisms. Data based on behavior and oxygen uptake experiment has confirmed their nature. They show an uptake rate of oxygen of 1760 µmol dm-3 h-1.[9] Even if they show an uptake rate similar to Thiomargarita spp., they do not have the same capacities to resist for a longer time in presence of oxygen.[11] For this reason, they populate OMZs (Oxygen Minimum Zone). [9]
Sulphur metabolism
Thioploca spp. has shown two types of response to sulphide based on its concentrations of it. They have a positive response to low sulphide (<100 µM) concentrations and negative to high concentrations.[6] [5]They show a maximum uptake rate at 200 µM.[9] This coupled with taxis towards nitrate, regulates the behavior of this genus. Also involved in it is the gradient of O2 affecting it in a minor way. For this reason, these microorganisms are defined as microaerophilic. Hypothetically they could be in competition with other sulphide oxidizing bacteria, but with the ability to accumulate nitrate they create a perfect strategy to access both electron donor and acceptor at the same moment. [12][6]
Based on some research, we know that oxidized iron is important in process of scavenging H2S (hydrogen sulphide), although the precise mechanism is unknown. [13]At the same time, the inhabited sheaths of Thioploca can be covered by filamentous sulphate-reducing bacteria. These sulphate-reducing bacteria, pertaining to the genus Desulfonema, could explain the high rate of recycling of H2S and its availability also in sulphide-pore environments. [6]
Furthermore, the elemental sulphur accumulated in the cells as drops is involved in sulphur metabolism. This reaction is also involved oxygen which oxidates the elemental sulphur:
2S0+3O2+ 2H2O → 4SO42-+ 4H+
Another reaction, involving nitrate, is part of the oxidation:
4S0+3NO3-+ 7H2O → 4SO42-+ 3NH4++2H+
These two reactions occur at similar rates. A difference is situated in the uptake rate of sulphide that is 5-6 times faster with respect to the oxidation rate of elemental sulphur stored in the drops. Based on this we know that sulphide uptake is not coupled with carbon fixation.[9]
Nitrogen metabolism
Thioploca genus has shown also the capacity to accumulate nitrate and use the Dissimilatory nitrate reduction to ammonium (DNRA) pathway.[14][9][5][6] To obtain nitrate they perform a vertical migration. Sheats of Thioploca spp. are considered a compatible niche for the growth of anammox bacteria, due to the ability of Thioploca spp. to perform Dissimilative nitrate reduction to ammonium. [9]They are able to perform nitrite reduction and show positive taxis towards nitrite. [14]The dissimilatory nitrate reduction is involved also in the oxidation of sulphide that leads to a higher accumulation of elemental sulphur. A higher presence and reduction of nitrate increase drastically the fixation of carbon dioxide (CO2). In any case, nitrate uptake can occur also in low environmental concentrations. [9]
Species
Thioploca contains four species:[15]
References
- ^ eol
- ^ Jørgensen, B. B.; Gallardo, V. A. (1999). "Thioploca spp.: Filamentous sulfur bacteria with nitrate vacuoles". FEMS Microbiology Ecology. 28 (4): 301. doi:10.1111/j.1574-6941.1999.tb00585.x.
- ^ H. Fossing; V. A. Gallardo; B. B. Jørgensen; M. Hüttel; L. P. Nielsen; H. Schulz; D. E. Canfield; S. Forster; R. N. Glud; J. K. Gundersen; J. Küver; N. B. Ramsing; A. Teske; B. Thamdrup & O. Ulloa (2002). "Concentration and transport of nitrate by the mat-forming sulphur bacterium Thioploca". Nature. 374 (6524): 713–715. doi:10.1038/374713a0.
- ^ Gabe Paal (April 16, 1999). "Biggest bacteria ever found". EurekAlert!.
- ^ a b c d Jørgensen, Bo Barker; Teske, Andreas; Ahmad, Azeem (2015), "Thioploca", Bergey's Manual of Systematics of Archaea and Bacteria, John Wiley & Sons, Ltd, pp. 1–12, doi:10.1002/9781118960608.gbm01227, ISBN 978-1-118-96060-8, retrieved 2021-12-23
- ^ a b c d e Jørgensen, Bo Barker; Gallardo, Victor A (1999-04-01). "Thioploca spp.: filamentous sulfur bacteria with nitrate vacuoles". FEMS Microbiology Ecology. 28 (4): 301–313. doi:10.1111/j.1574-6941.1999.tb00585.x. ISSN 0168-6496.
- ^ Ferdelman, Timothy G.; Lee, Cindy; Pantoja, Silvio; Harder, Jens; Bebout, Brad M.; Fossing, Henrik (1997– August). "Sulfate reduction and methanogenesis in a Thioploca-dominated sediment off the coast of Chile". Geochimica et Cosmochimica Acta. 61 (15): 3065–3079. doi:10.1016/s0016-7037(97)00158-0. ISSN 0016-7037.
{{cite journal}}: Check date values in:|date=(help) - ^ Maier, Siegfried; Gallardo, Victor A. (1984-10). "Nutritional characteristics of two marine thioplocas determined by autoradiography". Archives of Microbiology. 139–139 (2–3): 218–220. doi:10.1007/bf00402003. ISSN 0302-8933.
{{cite journal}}: Check date values in:|date=(help) - ^ a b c d e f g h i j Høgslund, Signe; Revsbech, Niels Peter; Kuenen, J. Gijs; Jørgensen, Bo Barker; Gallardo, Victor Ariel; Vossenberg, Jack van de; Nielsen, Jeppe Lund; Holmkvist, Lars; Arning, Esther T.; Nielsen, Lars Peter (2009-06). "Physiology and behaviour of marine Thioploca". The ISME Journal. 3 (6): 647–657. doi:10.1038/ismej.2009.17. ISSN 1751-7370.
{{cite journal}}: Check date values in:|date=(help) - ^ Fossing, H.; Gallardo, V. A.; Jørgensen, B. B.; Hüttel, M.; Nielsen, L. P.; Schulz, H.; Canfield, D. E.; Forster, S.; Glud, R. N.; Gundersen, J. K.; Küver, J. (1995-04). "Concentration and transport of nitrate by the mat-forming sulphur bacterium Thioploca". Nature. 374 (6524): 713–715. doi:10.1038/374713a0. ISSN 1476-4687.
{{cite journal}}: Check date values in:|date=(help) - ^ Schulz, Heide N.; de Beer, Dirk (2002-11). "Uptake Rates of Oxygen and Sulfide Measured with Individual Thiomargarita namibiensis Cells by Using Microelectrodes". Applied and Environmental Microbiology. 68 (11): 5746–5749. doi:10.1128/AEM.68.11.5746-5749.2002. ISSN 0099-2240. PMID 12406774.
{{cite journal}}: Check date values in:|date=(help) - ^ Nelson, Douglas C.; Jørgensen, Bo Barker; Revsbech, Niels Peter (1986-08). "Growth Pattern and Yield of a Chemoautotrophic Beggiatoa sp. in Oxygen-Sulfide Microgradients". Applied and Environmental Microbiology. 52 (2): 225–233. doi:10.1128/aem.52.2.225-233.1986. ISSN 0099-2240.
{{cite journal}}: Check date values in:|date=(help); line feed character in|title=at position 47 (help) - ^ Thamdrup, Bo; Canfield, Donald E. (1996). "Pathways of carbon oxidation in continental margin sediments off central Chile". Limnology and Oceanography. 41 (8): 1629–1650. doi:10.4319/lo.1996.41.8.1629. ISSN 1939-5590.
- ^ a b Otte, null; Kuenen, null; Nielsen, null; Paerl, null; Zopfi, null; Schulz, null; Teske, null; Strotmann, null; Gallardo, null; Jorgensen, null (1999-07). "Nitrogen, carbon, and sulfur metabolism in natural thioploca samples". Applied and Environmental Microbiology. 65 (7): 3148–3157. doi:10.1128/AEM.65.7.3148-3157.1999. ISSN 1098-5336. PMID 10388716.
{{cite journal}}: Check date values in:|date=(help) - ^ A. Teske; N. B. Ramsing; J. Küver & H. Fossing (1996). "Phylogeny of Thioploca and related filamentous sulfide-oxidizing bacteria". Systematic and Applied Microbiology. 18 (4): 517–526.
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