Even if you’re alone this Valentine’s Day, don’t worry: some parts of your body will be in full action. Indeed, your body will welcome a veritable carnival of the sensual in your belly, as your microbiota will indulge in an orgy of sex and swinger parties where they will exchange genes rather than keys.
The salacious gene
Imagine you have a serious illness with a very unusual cure: you can cure it by having sex with someone who will then pass on the genes needed to cure your illness. It is, as they say, sexual healing. Using sex for protection or healing is precisely what bacteria can do, and it is a crucial defense mechanism.
In the past, the research community believed that bacterial sex (or mating, as scientists call it) posed a terrible threat to humans, as this ancient process can spread DNA capable of transmitting antibiotic resistance to their neighbours. Antibiotic resistance is one of the most pressing health issues facing the world, and is expected to cause 10 million deaths per year by 2050.
But there’s more to this bacterial sex than meets the eye. Recently, scientists from the University of Illinois at Urbana-Champaign and the University of California, Riverside observed that gut microbes shared the ability to acquire a vital nutrient from each other through bacterial sex. Patrick Degnan, UCR microbiologist and study leader, says:
“We are excited about this study because it shows that this process is not just about antibiotic resistance. Horizontal gene exchange between microbes is likely used for anything that increases their ability to survive, including the sharing of vitamin B12.
For more than 200 years, researchers have known that bacteria reproduce by fission, where one cell splits in two to produce two genetically identical daughter cells. However, in 1946, Joshua Lederberg and Edward Tatum discovered that bacteria could exchange genes through conjugation, an act entirely separate from reproduction.
Conjugation occurs when a donor bacterium and a recipient bacterium approach each other, whereupon the donor creates a tube, called a pilus, which attaches to the recipient and brings the two cells together. A small packet of DNA is then passed from the donor to the recipient, providing new genetic information through horizontal transfer.
Ironically, it wasn’t until Lederberg met and fell in love with his wife, Esther Lederberg, that they made headway in bacterial sex.
widely recognized as pioneer of bacterial genetics, Esther was still struggling for recognition despite identifying the horizontal transfer of antibiotic resistance and viruses, which kill bacteria called bacteriophages. She discovered these phages after noticing small objects nibbling at the edges of her bacterial colonies. Descending to find out how they got there, she found these viral intruders hiding dormant among bacterial chromosomes after being transferred by microbes during sex.
Later work revealed that environmental stresses such as disease activated these viruses to replicate in their hosts and kill them. Yet scientists assumed that bacterial sex was purely a defense mechanism.
Promiscuity is synonymous with longevity
The recently published study builds on Esther’s work. The study authors believed that this bacterial process extends beyond antibiotic resistance. So they started by studying how vitamin B12 entered intestinal microbial cells, where the cells had previously been unable to extract this vitamin from their environment – which was confusing because, without vitamin B12, most types of living cells would not can’t work. Therefore, many questions remained about how these organisms survived without the machinery to extract this resource from the gut.
The new study by Cell reports use it Bacteroidetes species, which make up to 80% of the human microbiome in the intestines, where they break down complex carbohydrates into energy.
“The large, long molecules in sweet potatoes, beans, whole grains and vegetables would pass through our bodies entirely without these bacteria. They break them down so we can get energy from them,” the team explained.
This bacterium was placed in laboratory dishes by mixing those that could extract B12 from the stomach with others that could not. The team then watched in awe as the bacteria formed their sex pilus to transfer genes for B12 extraction. After the experiment, the researchers looked at the total genetic material of the recipient microbe and found that it had incorporated an extra band of donor DNA.
Among living mice, something similar happens. When the group administered two different subsets of Bacteroidetes to a mouse – one that had the transfer genes for B12 and one that did not – they found that the genes ‘jumped’ to the recipient after five to nine days. .
“In a given organism, you can see bands of DNA that look like fingerprints. Recipients of B12 carriers had an additional band showing new DNA they had obtained from a donor,” Degnan said.
Remarkably, the team also noted that different phage species were also transferred upon conjugation, exhibiting bacterial subgroup specificity in some cases. These viruses have also shown the ability to modify the genomic sequence of its bacterial host, with the power to promote or demote the life of its microbial vessel when activated.
Sexual activity in our intestines keeps us healthy
Interestingly, the authors note that they could not observe conjugation in all subgroups of the Bacteroidetes species, suggesting that this could be due to growth factors in the gut or a possible subgroup barrier within this large group of species slowing the process.
Despite this, Degnan says, “We are excited about this study because it shows that this process is not just about antibiotic resistance. And that “the horizontal exchange of genes between microbes is probably used for anything that increases their ability to survive, including sharing [genes for the transport of] vitamin B12.
This means that bacterial sex doesn’t just happen when microbes are attacked; It happens all the time. And it’s probably part of what keeps the microbiome and, by extension, ourselves fit and healthy.