Desulfobacterales

Desulfobacterales are an order of sulfate-reducing bacteria within the phylum Thermodesulfobacteria.[1] The order contains three families; Desulfobacteraceae, Desulfobulbaceae, and Nitrospinaceae.[2] The bacterium in this order are strict anaerobic respirators, using sulfate or nitrate as the terminal electron acceptor instead of oxygen. Desulfobacterales can degrade ethanol, molecular hydrogen, organic acids, and small hydrocarbons.[3][4] The bacterium of this order have a wide ecological range and play important environmental roles in symbiotic relationships and nutrient cycling.

Desulfobacterales
Stromatolites next to a volcanic lake, found to harbor abundant Desulfobacterales
Scientific classification
Domain:
Bacteria
Phylum:
Thermodesulfobacteriota
Class:
Desulfobacteria
Order:
Desulfobacterales
Families

Habitat

Desulfobacterales are found globally and often in extreme environments, such as deep-sea hydrothermal vents, hot springs, marine sediment, and solfataric fields, an area of volcanic venting that gives off sulfurous gases.[5][6]

Symbiotic Relationships

Sulfate-reduction by Desulfobacteraceae and Desulfobulbaceae in coastal marine sediments plays an important role in molecular hydrogen cycling through a close relationship with fermenting microorganisms.[7] Fermenting microbes break down organic materials on the seafloor and produce molecular oxygen and organic acids. Molecular hydrogen is an essential electron donor used by Desulfobacterales; they use the molecular hydrogen produced by fermentation to drive sulfate reduction. This feedback loop maintains molecular hydrogen at an energetically favorable level for fermenting respiration and provides ample molecular hydrogen for sulfate reduction.[7]

Nitrogen Cycling
Nitrogen cycle pathways in mangrove ecosystems.

Human activity, such as increased fertilizer use, has caused nitrogen pollution in inland and coastal waters. An influx of nitrogen inputs into aquatic ecosystems can cause negative effects such as eutrophication, resulting in anoxic conditions.[8] Desulfobacterales are important in nitrogen pollution mitigation in coastal mangrove ecosystems through nitrate reduction.[9] Nitrate is reduced by Desulfobacterales species via dissimilatory nitrate reduction genes. Dissimilatory nitrate reduction accounts for roughly 75.7–85.9% of nitrate reduction in mangrove ecosystems.[9] Dissimilatory nitrate reduction is important because nitrate is reduced to ammonium, which can then be taken up by other microorganisms and plants in the system.[9]

References
  1. Waite, David W; Chuvochina, Maria; Pelikan, Claus; Parks, Donovan H; Yilmaz, Pelin; Wagner, Michael; Loy, Alexander; Naganuma, Takeshi; Nakai, Ryosuke; Whitman, William B; Hahn, Martin W; Kuever, Jan; Hugenholtz, PhilipYR 2020 (2020). "Proposal to reclassify the proteobacterial classes Deltaproteobacteria and Oligoflexia, and the phylum Thermodesulfobacteria into four phyla reflecting major functional capabilities". International Journal of Systematic and Evolutionary Microbiology. 70 (11): 5972–6016. doi:10.1099/ijsem.0.004213. ISSN 1466-5034. PMID 33151140. S2CID 226257730.
  2. "ITIS - Report: Desulfobacterales". www.itis.gov. Retrieved 2022-10-02.
  3. Govil, Tanvi; Rathinam, Navanietha K.; Salem, David R.; Sani, Rajesh K. (2019-01-01), Das, Surajit; Dash, Hirak Ranjan (eds.), "Chapter 35 - Taxonomical Diversity of Extremophiles in the Deep Biosphere", Microbial Diversity in the Genomic Era, Academic Press, pp. 631–656, ISBN 978-0-12-814849-5, retrieved 2022-11-06
  4. Marozava, Sviatlana; Mouttaki, Housna; Müller, Hubert; Laban, Nidal Abu; Probst, Alexander J.; Meckenstock, Rainer U. (2018-02-01). "Anaerobic degradation of 1-methylnaphthalene by a member of the Thermoanaerobacteraceae contained in an iron-reducing enrichment culture". Biodegradation. 29 (1): 23–39. doi:10.1007/s10532-017-9811-z. ISSN 1572-9729. PMC 5773621. PMID 29177812.
  5. "solfatara | geology". www.britannica.com. Retrieved 2022-11-06.
  6. Saini, Rashmi; Kapoor, Rupam; Kumar, Rita; Siddiqi, T. O.; Kumar, Anil (2011-11-01). "CO2 utilizing microbes — A comprehensive review". Biotechnology Advances. 29 (6): 949–960. doi:10.1016/j.biotechadv.2011.08.009. ISSN 0734-9750. PMID 21856405.
  7. Dyksma, Stefan; Pjevac, Petra; Ovanesov, Kin; Mussmann, Marc (February 2018). "Evidence for H 2 consumption by uncultured Desulfobacterales in coastal sediments: H 2 -consuming sulfate reducers in coastal sediments". Environmental Microbiology. 20 (2): 450–461. doi:10.1111/1462-2920.13880. PMID 28772023. S2CID 44713600.
  8. Camargo, Julio A.; Alonso, Álvaro (2006-08-01). "Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment". Environment International. 32 (6): 831–849. doi:10.1016/j.envint.2006.05.002. hdl:10261/294824. ISSN 0160-4120. PMID 16781774.
  9. Nie, Shiqing; Zhang, Zufan; Mo, Shuming; Li, Jinhui; He, Sheng; Kashif, Muhammad; Liang, Zhengwu; Shen, Peihong; Yan, Bing; Jiang, Chengjian (2021-05-15). "Desulfobacterales stimulates nitrate reduction in the mangrove ecosystem of a subtropical gulf". Science of the Total Environment. 769: 144562. Bibcode:2021ScTEn.769n4562N. doi:10.1016/j.scitotenv.2020.144562. ISSN 0048-9697. PMID 33460836. S2CID 231641138.


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