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Pasteur point

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Switch from fermentation to aerobic respiration

The Pasteur point is a level of oxygen (about 0.3% by volume which is less than 1% of Present Atmospheric Level or PAL) above which facultative aerobic microorganisms and facultative anaerobes adapt from fermentation to aerobic respiration. It is also used to mark the level of oxygen in the early atmosphere of the Earth that is believed to have led to major evolutionary changes. It is named after Louis Pasteur, the French microbiologist who studied anaerobic microbial fermentation, and is related to the Pasteur effect.

It was once supposed that about 400 million years ago, in the Cambrian period, the level of oxygen in the atmosphere rose from 0.1 to 1 percent of present atmospheric level. Supposedly, this led to many organisms adapting from fermentation to respiration, leading to organisms evolving photosynthesis and what is termed the Cambrian explosion of species. It has also been suggested that this increased oxygen level reduced the influence of ultraviolet radiation.

It is now well documented that oxygen level reached at least 10% of the present value 2.4 billion years ago (for details see Great Oxygenation Event).

See also

  • Pasteur effect – Inhibiting effect of oxygen on the fermentation process
  • L'Atalante basin – Anoxic hypersaline brine basin at the bottom of the Mediterranean Sea

References

  1. Engelhardt, W. A. (1974). "On the dual role of respiration". Molecular and Cellular Biochemistry. 5 (1): 25–33. doi:10.1007/BF01874169. PMID 4372523. S2CID 40991988.
  2. Rutten, MG (1970). "The history of atmospheric oxygen". Origins of Life and Evolution of Biospheres. 2 (1): 5–17. Bibcode:1970SLSci...2....5R. doi:10.1007/BF00928950. PMID 5521892. S2CID 21984448.
  3. Berkner, L. V.; Marshall, L. C. (1965). "History of major atmospheric components". Proceedings of the National Academy of Sciences. 53 (6): 1215–1226. Bibcode:1965PNAS...53.1215B. doi:10.1073/pnas.53.6.1215. ISSN 0027-8424. PMC 219811.
  4. Berkner, L. V.; Marshall, L. C. (1 May 1965). "On the origin and rise of oxygen concentration in the Earth's Atmosphere". Journal of the Atmospheric Sciences. 22 (3): 225–261. Bibcode:1965JAtS...22..225B. doi:10.1175/1520-0469(1965)022<0225:OTOARO>2.0.CO;2.
  5. Berkner, L. V. & Marshall, L. C. (1965). Oxygen and evolution. New Scientist, 28, 415-9.
  6. Berkner, L. V.; Marshall, L. C. (1987), "Oxygen, evolution in atmosphere", Climatology, Dordrecht: Kluwer Academic Publishers, pp. 644–656, doi:10.1007/0-387-30749-4_130, ISBN 978-0-87933-009-5, retrieved 2022-10-07
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