In 2015, EPFL researchers led by Melanie Blokesch published a seminal paper in Science showing that the bacterium responsible for cholera, Vibrio cholerae, uses a spring-loaded spear to literally stab neighboring bacteria and steal their DNA. They identified the spear mechanism to be the so-called “type VI secretion system” or T6SS, also used for interbacterial competition by many other bacteria.
V. cholerae uses its T6SS to compete with other bacteria in its aquatic environment and acquire new genetic material, which the pathogen absorbs and exchanges against some parts of its own genome. This mode of “horizontal gene transfer” leads to rapid evolution and pathogen emergence. The pathogen V. cholerae has caused seven major cholera pandemics since 1817 and, according to current WHO data, still kills more than 100,000 people each year and infects up to 4 million others, mostly in poor or underdeveloped countries.
Now, Blokesch’s group has discovered the extent of DNA that V. cholerae can steal in a single attack: more than 150,000 nucleic acid base pairs, or roughly 150 genes in one go (the cholera bacterium carries around 4,000 genes in total). The researchers calculated this number by sequencing the entire genome of almost 400 V. cholerae strains before and after stealing DNA from their neighboring bacteria…
The authors conclude that the environmental “lifestyle” of V. cholerae enables exchange of genetic material with enough coding capacity that it can significantly accelerate the evolution of the bacterium.
“This finding is very relevant in the context of bacterial evolution,” says Blokesch. “It suggests that environmental bacteria might share a common gene pool, which could render their genomes highly flexible and the microbes prone to quick adaption.” Paper. (open access) – Noémie Matthey, Sandrine Stutzmann, Candice Stoudmann, Nicolas Guex, Christian Iseli, Melanie Blokesch. Neighbor predation linked to natural competence fosters the transfer of large genomic regions in Vibrio cholerae. eLife, 2019; 8 DOI: 10.7554/eLife.48212 More.
Relevant in more ways than one. Remember that recent Atlantic article where the writer was grousing that her school didn’t teach “evolution” (Darwinism)?:
[Glenn] Branch [of NCSE, the Darwin-in-the-schools lobby] says lacking a knowledge of human evolution might make it harder for, say, doctors to understand superbugs, or for farmers to understand the nuances of agriculture. I’m a little skeptical of that argument. There are great doctors in Texas, and certainly plenty of great farmers too. The internet wasn’t as ubiquitous when I was in high school, but it was still possible to read and explore on one’s own. Today, that’s even easier.Olga Khazan, “I Was Never Taught Where Humans Came From” at The Atlantic
She’s right to be skeptical and it’s even worse than she thinks: Dangerous bacteria like cholera seem to use methods much faster than Darwinism to do their stuff. But how many “evolution” lobbies besiege school boards to teach horizontal gene transfer? Is that because they can’t use it the way they can use Darwinism, to front the idea that humans are just animals? Nah. Must be something else…
See also: A cry from grievance culture: She never learned Darwinism in school. If Darwinists had been in charge of Khazan’s education, she would mainly have a bunch of stuff to unlearn.
Horizontal gene transfer: Sorry, Darwin, it’s not your evolution any more