Review:
A fascinating story of bacteria cohabitating with humans, plants and other animals. Corrects a myth that we have many more bacteria than our own human cells. Contains numerous examples of symbiosis with bacteria. Suggests that two bacteria combined together and this led to our cells containing mitochondria. Very up to date with the latest developments and interestingly presented.
Inspect the whole Science Section -->
It is believed that they were created about 2.5 billion years ago, when bacterium merged with an archaeon. The archaeon provided the chassis of the eukaryotic cell while the bacterium eventually transformed into the mitochondria. Our genomes contain genes that have an archaeal and bacterial character.
The latest estimates suggest that we have around 30 trillion human cells and 39 microbial ones. Our cells carry between 20 to 25 thousand genes, but microbes inside us contain around 500 times more.
The bacteria don’t physically reshape the gut themselves. Instead they teach the gut cells how to use their own genes to make a healthy gut. This has been demonstrated with mice and gut bacterium called Bacteroides thetaiotaomicron.
The stomach bacterium Helicobacter pylori causes ulcers, but also protects against oesophageal cancer.
The soil-dwelling microbe called Bacillus thuringiensis produces toxins that can kill insects by punching holes in their guts. Farmers explored it since 1920 by spraying it onto crops.
A cut or bruise can split some of our cells apart and spill fragments of mitochondria into our blood – fragments that still keep some of their ancient bacterial character. When our immune system spots them, it mistakenly assumes that an infection is under way and mounts a strong defence. This can lead to a lethal condition called systemic inflammatory response syndrome, which can be worse than the original injury.
There is a special group of cells, called a bacteriocyte (Greek for bacteria cell), which accommodate bacteria. Up to a fifth of insect species contain them. They can control and use bacteria to their own good.
Viruses called bacteriophages (literally ‘eaters of bacteria’), or phages for short, look like the lunar lander and can be found in our intestines. They keep our microbes in check.
The bacteria in our gut almost all belong to four major groups, out of hundreds that exist in the wild. They are Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria.
Mitochondria were once free-living bacteria that became permanently enclosed within a larger cell. This process known as endosymbiosis was accepted thanks to Lynn Margulis. She argued that "Natural selection eliminates and maybe maintains, but it doesn't create", and maintained that symbiosis was the major driver of evolutionary change.
Unlike us, bacterias can transfer their DNA horizontally between each others. They can also absorb bits of DNA in their environment left by their dead or decaying neighbours. They can even rely on viruses to move genes from one cell to another. The horizontal gene transfer (HGT) allows bacteria to evolve at great speed. They don’t have to wait for the right mutations to slowly amass within their existing DNA. This leads to development of superbugs, protected against powerful antibiotics.
In 2001, when the first full draft of human genome was published, it was found that of the thousands of genes identified, 223 were shared with bacteria but not with other complex organisms. They were probably present in some very early organisms and then lost in later lineages.
The presence of Akkermansia muciniphilia in our gut correlates with a lower risk of obesity and malnutricion. The Bacteroides fragilis and Faecalibacterium prausnitzii are anti-inflammatory bugs helping our immune system.
Substances that selectively nourish beneficial microbes are called prebiotics.
Notes:
All eukaryotes pack almost all their DNA into a central nucleus and have mitochondria, which provides cell with chemical energy.It is believed that they were created about 2.5 billion years ago, when bacterium merged with an archaeon. The archaeon provided the chassis of the eukaryotic cell while the bacterium eventually transformed into the mitochondria. Our genomes contain genes that have an archaeal and bacterial character.
The latest estimates suggest that we have around 30 trillion human cells and 39 microbial ones. Our cells carry between 20 to 25 thousand genes, but microbes inside us contain around 500 times more.
The bacteria don’t physically reshape the gut themselves. Instead they teach the gut cells how to use their own genes to make a healthy gut. This has been demonstrated with mice and gut bacterium called Bacteroides thetaiotaomicron.
The stomach bacterium Helicobacter pylori causes ulcers, but also protects against oesophageal cancer.
The soil-dwelling microbe called Bacillus thuringiensis produces toxins that can kill insects by punching holes in their guts. Farmers explored it since 1920 by spraying it onto crops.
A cut or bruise can split some of our cells apart and spill fragments of mitochondria into our blood – fragments that still keep some of their ancient bacterial character. When our immune system spots them, it mistakenly assumes that an infection is under way and mounts a strong defence. This can lead to a lethal condition called systemic inflammatory response syndrome, which can be worse than the original injury.
There is a special group of cells, called a bacteriocyte (Greek for bacteria cell), which accommodate bacteria. Up to a fifth of insect species contain them. They can control and use bacteria to their own good.
Viruses called bacteriophages (literally ‘eaters of bacteria’), or phages for short, look like the lunar lander and can be found in our intestines. They keep our microbes in check.
The bacteria in our gut almost all belong to four major groups, out of hundreds that exist in the wild. They are Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria.
Mitochondria were once free-living bacteria that became permanently enclosed within a larger cell. This process known as endosymbiosis was accepted thanks to Lynn Margulis. She argued that "Natural selection eliminates and maybe maintains, but it doesn't create", and maintained that symbiosis was the major driver of evolutionary change.
Unlike us, bacterias can transfer their DNA horizontally between each others. They can also absorb bits of DNA in their environment left by their dead or decaying neighbours. They can even rely on viruses to move genes from one cell to another. The horizontal gene transfer (HGT) allows bacteria to evolve at great speed. They don’t have to wait for the right mutations to slowly amass within their existing DNA. This leads to development of superbugs, protected against powerful antibiotics.
In 2001, when the first full draft of human genome was published, it was found that of the thousands of genes identified, 223 were shared with bacteria but not with other complex organisms. They were probably present in some very early organisms and then lost in later lineages.
The presence of Akkermansia muciniphilia in our gut correlates with a lower risk of obesity and malnutricion. The Bacteroides fragilis and Faecalibacterium prausnitzii are anti-inflammatory bugs helping our immune system.
Substances that selectively nourish beneficial microbes are called prebiotics.
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