Purple sulfur bacteria
Purple sulfur bacteria | |
---|---|
Scientific classification | |
Domain: | Bacteria |
Phylum: | Pseudomonadota |
Class: | Gammaproteobacteria |
Order: | Chromatiales Imhoff 2005[1] |
Families | |
The purple sulfur bacteria (PSB) are part of a group of
The purple sulfur bacteria are largely divided into two families, the Chromatiaceae and the Ectothiorhodospiraceae, which produce internal and external sulfur granules respectively, and show differences in the structure of their internal membranes.[5] They make up part of the order Chromatiales, included in the Gammaproteobacteria. The genus Halothiobacillus is also included in the Chromatiales, in its own family, but it is not photosynthetic.
Characteristics of purple sulfur bacteria
Major photosynthetic pigments: Bacteriochlorophylls a or b
Location of photosynthetic pigments: Plasma membrane and chromatophore (lamellar membrane complexes that are continuous with the plasma membrane)
Photosynthetic electron donors: H2, H2S, S
Sulfur deposition: Inside the cell
Metabolic type: Photolithoautotroph[7]
Ecology
Habitat
Purple sulfur bacteria are generally found in illuminated anoxic zones of lakes and other aquatic habitats where hydrogen sulfide accumulates and also in "sulfur springs" where geochemically or biologically produced hydrogen sulfide can trigger the formation of blooms of purple sulfur bacteria. Anoxic conditions are required for photosynthesis; these bacteria cannot thrive in oxygenated environments.[8]
The most favorable lakes for the development of purple sulfur bacteria are
Purple sulfur bacteria can also be found and are a prominent component in
Ecological significance
Purple sulfur bacteria are able to affect their environment by contributing to
Some purple sulfur bacteria have evolved to optimize their environmental conditions for their own growth. For example, in the South Andros Black Hole in the Bahamas, purple sulfur bacteria adopted a new characteristic in which they are able to use their metabolism to radiate heat energy into their surroundings.[15] Due to the inefficiency of their carotenoids, or light-harvesting centres, the organisms are able to release excess light energy as heat energy.[15] This adaptation allows them to compete more effectively within their environment. By raising the temperature of the surrounding water, they create an ecological niche which supports their own growth, while also allowing them to outcompete other non-thermotolerant organisms.
Growth in meromictic lakes
Meromictic lakes are permanently stratified lakes produced by a gradient of saline concentrations. The highly salinated bottom layer is separated from the top layer of fresh water by the chemocline, where the salinity changes drastically. Due to the large difference in density, the upper and lower layers do not mix, resulting in an anoxic environment below the chemocline.[16] This anoxic environment with light and sufficient sulfide availability is ideal for purple sulfur bacteria.[17][16]
A study done at the Mahoney Lake suggested that purple sulfur bacteria contributes to the recycling of the inorganic nutrient, phosphorus.[16] The upwelling of purple sulfur bacteria into the top layer of water creates a source of bound phosphorus, and phosphatase activity releases this phosphorus into the water. The soluble phosphorus is then incorporated into heterotrophic bacteria for use in developmental processes. In this way, purple sulfur bacteria participates in the phosphorus cycle and minimizes nutrient loss.[16]
Biomarkers
Purple sulfur bacteria make
Bioremediation
Purple sulfur bacteria can contribute to a reduction of environmentally harmful organic compounds and odour emission in manure wastewater lagoons where they are known to grow. Harmful compounds such as methane, a greenhouse gas, and hydrogen sulfide, a pungent, toxic compound, can be found in wastewater lagoons. PSB can help lower the concentration of both, and others.[19]
Harmful organic compounds can be removed through photoassimilation, the uptake of carbon by organisms through photosynthesis.[20] When PSB in the lagoons perform photosynthesis they can utilize the carbon from harmful compounds, such as methane,[21] as their carbon source. This removes methane, a greenhouse gas, from the lagoon and reduces the lagoons' atmospheric pollution affect.
H2S can act as a sulfur source for PSB during these same photosynthetic processes that remove the organic compounds. The use of H2S as a reducing agent by PSB removes it from the lagoon and leads to a reduction of odour and toxicity in the lagoons.[22][23][24]
See also
References
- ^ IMHOFF (J.F.): Order I. Chromatiales ord. nov. In: D.J. BRENNER, N.R. KRIEG, J.T. STALEY and G. M. GARRITY (editors), Bergey's Manual of Systematic Bacteriology, second edition, vol. 2 (The Proteobacteria), part B (The Gammaproteobacteria), Springer, New York, 2005, pp. 1-3.
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- ^ "Wenzhouxiangella". www.uniprot.org.
- doi:10.1601/nm.27206 (inactive 2024-04-17).)
{{cite journal}}
: CS1 maint: DOI inactive as of April 2024 (link - ^ a b c d Hunter, C.N., Daldal, F., Thurnauer, M.C., Beatty, J.T. "The Purple Phototropic Bacteria", Springer-Dordrecht, 2008.
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- ^ Usha Mina, Pranav kumar (2014). Life science funtamental and practice.
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- ^ ISBN 978-0-306-47954-0. Retrieved 6 October 2017.
- ^ Hubas, C. et al. "Proliferation of Purple Sulphur Bacteria at the Sediment Surface Affects Intertidal Mat Diversity and Functionality", PLOS One, December 5, 2013. Retrieved February 12, 2020.
- ^ Stal LJ (2010) https://ac.els-cdn.com/S0925857409000160/1-s2.0-S0925857409000160-main.pdf?_tid=2a3d5a5e-cd79-11e7-aa3b-00000aacb35f&acdnat=1511130774_f1d9f08b3f0de5ea6f90b0d1427800bb Microphytobenthos as a biogeomorphological force in intertidal sediment stabilization. Ecol Eng 36: 236–245. doi:10.1016/ j.ecoleng.2008.12.032.
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- ^ McGarvey, JA, et al. http://onlinelibrary.wiley.com/doi/10.1111/j.1472-765X.2009.02683.x/epdf "Induction of Purple Sulfur Bacterial Growth in Dairy Wastewater Lagoons by Circulation." Letters in Applied Microbiology, vol. 49, no. 4, 2009, pp. 427-433.
- ^ "Photoassimilation | Definition of photoassimilation in English by Oxford Dictionaries." https://en.oxforddictionaries.com/definition/photoassimilation Oxford Dictionaries | English, Oxford Dictionaries, en.oxforddictionaries.com/definition/photoassimilation.
- ^ Leytem, AB, et al. https://ac.els-cdn.com/S0022030217305799/1-s2.0-S0022030217305799-main.pdf?_tid=a8cdccc8-cd79-11e7-8cad-00000aab0f6c&acdnat=1511130986_0d85d5d96ffb65e1ca976c83f8706f90 "Methane Emissions from Dairy Lagoons in the Western United States."Journal of Dairy Science, vol. 100, no. 8, 2017, pp. 6785-6803.
- ^ "Hydrogen sulfide." http://www.npi.gov.au/resource/hydrogen-sulfide National Pollutant Inventory, Australian Government Department of Environment and Energy, www.npi.gov.au/resource/hydrogen-sulfide.
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