The Great Oxidation Event: How Cyanobacteria Changed Life
We are so acclimatized to the presence of oxygen on our planet Earth, that we take it for granted. However, oxygen was absent from the earth’s atmosphere for close to half of its lifespan. When the earth was formed around 4.5 billion years ago, it had vastly different conditions. At that time, the earth had a reducing atmosphere, consisting of carbon dioxide, methane and water vapor, as opposed to the present-day atmosphere that consists primarily of nitrogen and oxygen. Though sunlight split the water vapor in the atmosphere into oxygen and hydrogen, the oxygen quickly reacted with methane and got locked into the earth’s crust, barely leaving any traces in the atmosphere. A silent, mysterious force worked to release oxygen steadily, until the very composition of the atmosphere changed. That mysterious entity happened to be a microbe: Cyanobacteria.
According to the noted biochemist Leslie Orgel, who pioneered research on the origins of life, the earliest onset of life on our planet occurred around 3.8 billion years ago. Since oxygen was projected to be absent from the earth at that time, metabolism in living organisms would have been anaerobic, involving the use of minerals present in the ocean to generate energy. However, around 2.7 billion years ago, a peculiar group of microbes, known as cyanobacteria, evolved. Phylogenetic analyses based on 16S and 23s rRNA, genome reconstructions and fossil evidence have been used to understand the evolutionary characteristics of these early living organisms. These microbes possessed the remarkable ability to perform photosynthesis, (i.e., they could generate energy from sunlight). Cyanobacteria possessed the machinery to utilize water as a fuel source by oxidizing it. More significantly, the by-product of photosynthesis happened to be oxygen.
Continued
https://asm.org/Articles/2022/Febru... Event and,life, creating an extinction event
We are so acclimatized to the presence of oxygen on our planet Earth, that we take it for granted. However, oxygen was absent from the earth’s atmosphere for close to half of its lifespan. When the earth was formed around 4.5 billion years ago, it had vastly different conditions. At that time, the earth had a reducing atmosphere, consisting of carbon dioxide, methane and water vapor, as opposed to the present-day atmosphere that consists primarily of nitrogen and oxygen. Though sunlight split the water vapor in the atmosphere into oxygen and hydrogen, the oxygen quickly reacted with methane and got locked into the earth’s crust, barely leaving any traces in the atmosphere. A silent, mysterious force worked to release oxygen steadily, until the very composition of the atmosphere changed. That mysterious entity happened to be a microbe: Cyanobacteria.
According to the noted biochemist Leslie Orgel, who pioneered research on the origins of life, the earliest onset of life on our planet occurred around 3.8 billion years ago. Since oxygen was projected to be absent from the earth at that time, metabolism in living organisms would have been anaerobic, involving the use of minerals present in the ocean to generate energy. However, around 2.7 billion years ago, a peculiar group of microbes, known as cyanobacteria, evolved. Phylogenetic analyses based on 16S and 23s rRNA, genome reconstructions and fossil evidence have been used to understand the evolutionary characteristics of these early living organisms. These microbes possessed the remarkable ability to perform photosynthesis, (i.e., they could generate energy from sunlight). Cyanobacteria possessed the machinery to utilize water as a fuel source by oxidizing it. More significantly, the by-product of photosynthesis happened to be oxygen.
Continued
https://asm.org/Articles/2022/Febru... Event and,life, creating an extinction event