Horizontal gene transfer: active in gut bacteria (Introduction)

by David Turell , Thursday, February 03, 2022, 22:28 (1023 days ago) @ David Turell

Latest study surprising:

https://www.sciencealert.com/there-are-a-bunch-of-bacteria-having-sex-in-your-gut-right...

"By forming a 'temporary union' with another bacterium in our gut, a microbe can therefore transfer its genes to another – it doesn't even have to be the same species.

"All the microbe has to do is stick out a tube, called a pilus, and attach itself to another cell, shooting off a transferable package of DNA called a mobile genetic element when it's ready.

"The discovery of bacterial sex was made over 70 years ago, when scientists realized this horizontal gene transfer was how microbes were sharing resistance genes for certain antibiotics, thereby spreading antibiotic resistance.

"More recently, it's become clear that bacterial sex doesn't just occur when microbes are under attack. It happens all the time, and it's probably part of what keeps our microbiome fit and healthy.

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"'The big, long molecules from sweet potatoes, beans, whole grains, and vegetables would pass through our bodies entirely without these bacteria," explains microbiologist Patrick Degnan from the University of California Riverside.

"'They break those down so we can get energy from them."

"To colonize the human gut and help us break down carbohydrates, however, these microbes must compete for limited resources in the large intestine. Such resources include vitamin B12 and other related compounds, which help fuel the bacteria's metabolism and synthesis of proteins.

"Most microbes in the gut don't have the ability to synthesize these crucial compounds on their own, which means they have to soak up what they can from their environment.

"For this to be effective, it pays to have genes for an efficient vitamin B12 transport system at the ready.

"In both petri dishes and in living mouse models, researchers have now identified B12 transporters that are shared via bacterial sex.

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"'The horizontal gene exchange among microbes is likely used for anything that increases their ability to survive, including sharing [genes for the transport of] vitamin B12."

"When two gut microbes were placed on a dish in the lab, researchers noticed the bacterium that couldn't synthesize B12 transport systems connected up with the bacterium that could. Once the sex pilus bridged the gap between the two, the 'receiving' bacterium could unpack its precious cargo.

"After the experiment, researchers examined the genome of the receiving bacterium, which was still alive, and found it had incorporated an extra band of DNA from the donor.

"Among living mice, something similar appears to happen. When researchers administered two forms of Bacteroidetes to a mouse – one that possessed the genes for transferring B12, and another that didn't – they found the genes of the former had 'jumped' to the latter after five to nine days."

Comment: a well-recognized process now shown to happen in very short times. Luckily for us the gut bacteria like to work for us and process veggies we cannot on our own.