Pasteur point
Encyclopedia
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 aerobic microorganisms and facultative anaerobes adapt from anaerobic respiration
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
. As it was previously supposed, 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. 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. Now it is well documented that oxygen level reached at least 10% of present 2,4 billion years ago (for details see Great Oxygenation Event
).
Anaerobic respiration
Anaerobic respiration is a form of respiration using electron acceptors other than oxygen. Although oxygen is not used as the final electron acceptor, the process still uses a respiratory electron transport chain; it is respiration without oxygen...
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
Louis Pasteur
Louis Pasteur was a French chemist and microbiologist born in Dole. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies and anthrax. His experiments...
the French microbiologist who studied anaerobic microbial fermentation and is related to the Pasteur effect
Pasteur effect
The Pasteur effect is an inhibiting effect of oxygen on the fermentation process.-Discovery:The effect was discovered in 1857 by Louis Pasteur, who showed that aerating yeasted broth causes yeast cell growth to increase, while conversely, fermentation rate decreases.-Explanation:The effect can be...
. As it was previously supposed, 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. This led to many organisms adapting from fermentation to respiration leading to organisms evolving photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
and what is termed the Cambrian explosion
Cambrian explosion
The Cambrian explosion or Cambrian radiation was the relatively rapid appearance, around , of most major phyla, as demonstrated in the fossil record, accompanied by major diversification of other organisms, including animals, phytoplankton, and calcimicrobes...
of species. It has also been suggested that this increased oxygen level reduced the influence of Ultraviolet radiation. Now it is well documented that oxygen level reached at least 10% of present 2,4 billion years ago (for details see Great Oxygenation Event
Great Oxygenation Event
The Great Oxygenation Event , also called the Oxygen Catastrophe or Oxygen Crisis or Great Oxidation, was the biologically induced appearance of free oxygen in Earth's atmosphere. This major environmental change happened around 2.4 billion years ago.Photosynthesis was producing oxygen both before...
).