When humans talk about microbes, they often think of this invisible and hostile force that must not be spared. Yet nearly 95% of bacteria are at peace with humanity or even render us irreplaceable services in the biosphere. For viruses, this percentage is even higher.
Posted on January 30, 2021 at 10:00 a.m.
–
–
Moreover, in these times of pandemic when the phobia for the world of microbes is at its height, I wondered what the fight against COVID-19 would be without the discreet bacterial contribution to our protection effort. Indeed, bacteria have known viruses for much longer than humans, because they have been around them since the earliest days of life on the planet.
Viruses called bacteriophages, which abound on continents and in waters, continually kill bacterial populations. Also, by dint of tasting their medicine in this open war and certainly more than 3 billion years old, bacteria have refined their defenses and developed tools that we have recovered and put at the service of scientific research, including the one devoted to the fight against COVID-19. So even if, traumatized by a virus, we spray ourselves with gels cursing the microbial world, it is important not to forget this precious bacterial contribution to our fight against this coronavirus.
To better remind, once again, the importance of preserving biodiversity even in these microbial forms, allow me to tell you why this duty of recognition towards their participation in our protection effort is so important.
Faced with the deadly attacks of viruses, certain bacteria have developed over the course of evolution a very particular immunization technique. What is it about ? When a bacterium is infected, it happens that it captures a piece of the genetic material of the bacteriophage and integrates it into its own genome to keep a memory of the passage of the attacker. By multiplying, the bacterium which survived this first attack then produces a line which will carry the mark. As a result, in the event of a second attack, these sensitized generations will be able to kill the virus by cutting its genome at this place that they have in a way photocopied and kept as a souvenir.
This mechanism is comparable to the work done by memory T cells in our immune system. This group of white blood cells also has the particularity of memorizing the identity of former aggressors and of organizing a faster and more dazzling response in the event of a second attack. This adaptive bacterial immunity can also be compared to the principle of vaccination in humans. In both cases, familiarization with the aggressor allows one to prepare, to stand firm and to beat him more effectively in the second encounter.
On the other hand, if our immune system uses antibodies as a fighting weapon, these bacteria defend themselves using a molecular scissor which has become very popular in laboratories. Indeed, this virus-fatal genomic circumcision tool was one day discovered and used by researchers, who named it CRISPR-Cas9. An acronym whose meaning I will spare you so as not to torment those who are not initiated into the vocabulary of molecular genetics. Without going into details, I just wanted to remind here that it is thanks to this bacterial mechanism that we have developed some of the rapid tests used to track the presence of SARS-CoV-2 in nasopharyngeal swabs.
PHOTO MIGUEL RIOPA, AGENCE FRANCE-PRESSE ARCHIVES
Emmanuelle Charpentier and Jennifer Doudna, winners of the 2020 Nobel Prize in chemistry
–
The CRISPR-Cas9 system is so innovative in research that humanity has praised not the bacterial genius, but the work of Emmanuelle Charpentier and Jennifer Doudna by awarding them the 2020 Nobel Prize in chemistry for this prodigious and frightening discovery for some. for the others.
Indeed, if in medical research, this scalpel in the service of gene surgery is seen as a golden opportunity for the advancement of gene therapies, for ethicists, it also opens the door wide to experimental drifts of modification of living organisms. , especially human embryos.
But that’s really not the bacteria problem anymore.
We must also thank bacteria for another legacy that allows us to do the famous PCR (polymerase chain reaction) tests which are at the center of strategies in the fight against COVID-19. In this method, the tool borrowed from microbes, Taq polymerase, is an enzyme that has been discovered in a bacteria that is very resistant to heat. A species called Thermus aquaticus (Taq) that researcher Thomas Brock found in 1966 in a hot spring in Yellowstone Park. It is the adaptive prowess of this species that is primarily the basis of the PCR technique. This valuable process, which allows infinitesimal amounts of DNA to be considerably amplified, has given a spectacular boost to research in molecular genetics.
In addition to its role in screening tests, PCR was also on the menu during the decryption of the virus and certainly in the development of RNA vaccines supposed to get us out of this health, economic and social nightmare that we are going through. The use of Taq polymerase in PCR technology earned Kary Bank Mullis and Michael Smith the 1993 Nobel Prize in Chemistry. Today, in addition to Taq polymerase, similar enzymes from other species allow to do PCR. A transfer of competence for which, failing to give it a price, we should perhaps sometimes take our hats off and salute bacterial biodiversity for the services rendered to humanity.
The moral of this molecular chronicle is as follows: even a bacterium, however useless it may be in our imagination, has something to teach us.
This is also why African wisdom teaches that a weed is nothing more than a plant whose virtues we do not yet know.
But how can we make this discernment understandable to a species deeply inhabited by a utilitarian vision of creation? The human is this bipedal who idolizes living beings that serve his interests, but for others, the qualifier of harmful or useless species is never far away.
A small proposal to finish. Instead of the humanism that is on everyone’s lips, why not teach our children about the environment that celebrates the relevance of all lives? Ecologism has the merit of being less anthropocentric than humanism, which seems to raise ever higher the wall that separates us from the rest of the living by positioning human feelings at the center of our short passage in the biosphere.
–
![WLAN multiroom speaker MEDION P61084 (MD 43187), Spotify Connect, DLNA, USB, Aux-in, for 19 euros [Medion Essen / lokal]](https://static.mydealz.de/live/threads/thread_full_screen/default/1744862_1.jpg "WLAN multiroom speaker MEDION P61084 (MD 43187), Spotify Connect, DLNA, USB, Aux-in, for 19 euros [Medion Essen / lokal]")
