pathogens, pathogens; Pathogens everywhere

I’ve always wondered about the way germophobes think – like there’s some way to escape pathogens. be germ phobic:

• You haven’t looked through a microscope lately.
• They have limited knowledge of bacteriology and virology.
• They have not paid attention to the human microbiome and human virome studies that have made headlines in recent years.
• They think of all numbers over a billion simply as “many.”
• Believe all the commercials you see on TV for antiseptic products that promise to keep you germ-free.
• You deny the essence of your own existence (as will be explained).

let me explain

bacteria

There are around 30,000 officially named Types of bacteria isolated as pure cultures in the laboratory and examined physiologically. But that’s just a drop in a rain shower. If you add in the unofficially named species, the number is likely closer to a billion. But remember that we are only talking about species of bacteria, not individual bacteria. When you consider that there are trillions and trillions of individual bacteria in each of these species (well, lots of them, at least), the numbers get really interesting. In fact, the number of bacteria on earth is estimated 5,000,000,000,000,000,000,000,000,000,000. That’s five million trillion trillion, or 5 x 10 to the power of 30.

Out of all these bacteria, it is estimated that only about 10,000 microbial species interact with the human ecosystem. Also, only about 500 to 1,000 of these species live in the human gut. In contrast to bacterial species as a whole, the researchers have calculated that between 81 and 99 percent of all microorganism genera in healthy adults have been identified.

Although most bacteria are harmless or often beneficial, some are pathogenic, with fewer than a hundred species known to cause infectious disease people. In fact, a large proportion of the bacteria in the human ecosystem are useful. The human intestinal flora enables digestion. Soil bacteria drive the decomposition process. Without bacteria, our ecosystem would collapse.

In bacteria, scientists have only recently begun to quantify the microbiome, finding that it is inhabited by at least 38 trillion bacteria. Perhaps more fascinating, bacteria aren’t the most common microbes that live in and on our bodies. This award goes to Viruses – at a cosmological mile.

viruses

It is estimated that for every bacterium on earth there are 10 viruses. There are an estimated 10 million (10 to the power of 31) individual viruses on Earth. That’s one for every star in the universe 100 million times. If you lined them all up, that line would be 10 million light years long! To put it more earthly, it has been estimated that more than 700 million viruses, mostly of marine origin, are deposited from the earth’s atmosphere every day every square meter the surface of our planet. As Katherine Wu writes in National Geographic, “Viruses infiltrate every aspect of our natural world, simmering in seawater, drifting through the atmosphere and lurking in tiny crumbs of earth. These pathogens, generally thought of as non-living entities, can only reproduce with the help of a host and are capable of abducting organisms from any branch of the tree of life – including a variety of human cells.

“Nevertheless, most of the time our species manages to live relatively disease-free in this virus-ridden world. The reason has less to do with the human body’s resistance to disease and more to do with the biological quirks of viruses themselves, says Sara Sawyer, a virologist and disease ecologist at the University of Colorado Boulder. These pathogens are extraordinarily picky about the cells they infect, and only a tiny fraction of the viruses that surround us actually pose a threat to humans.”

So how many of these viruses interact with humans?

Biologists estimate that there are currently 380 trillion viruses living on and in your body – ten times as many bacteria as bacteria. Some can cause disease, but many simply coexist with you. Together they are known as the human virome. But the overwhelming number of these viruses aren’t the dangerous ones you usually hear about, like the ones that cause the flu or the common cold or COVID-19. In fact, many of these viruses infect the harmful bacteria that live inside you and on your skin, protecting you by destroying them.

All in all, of the millions and millions of different virus species in the world, only about 200 virus species are known to cause disease in humans.

And then there is DNA

So what have we learned so far?

• Viruses and bacteria exist in greater numbers than we can count or imagine.
• They exist all around us in everything we touch, step on, bathe and breathe.
• They are inevitable.
• The vast majority are completely indifferent to our existence and have nothing to do with us.
• However, many are beneficial to our existence.
• Only a tiny percentage is harmful.

And if all of that isn’t enough to freak out our germ-hating readers, what we’re about to discuss should seal the deal.

• Bacteria and humans have been exchanging DNA for thousands of years.
• About 8-10 percent of human DNA comes from viral DNA that was inserted into our genomes in the distant past, in many cases the genomes of our prehuman ancestors millions of years ago (or when God created the creatures of the earth, if you understand that want). prefer). Most of these viral genes come from retroviruses, RNA viruses that insert DNA copies of their own genes into our genome when they infect cells.
• Human cells make up only 43% of the total cell count in the body. The rest are microscopic colonists. In other words, more than half of your body is not human.

viral DNA

When viruses infect us, they can embed small pieces of their genetic material into our DNA. Although rare, the incorporation of this material into the human genome has been occurring since the dawn of man. As a result of this ongoing process, viral genetic material makes up nearly 10 percent of the modern human genome. Over time, the vast majority of viral invaders that populate our genome have mutated to the point where they no longer lead to active infections. But they are not entirely dormant.

Sometimes these blind sequences of viral genes can contribute to the development of diseases such as cancer and Alzheimer’s. They can also make their hosts susceptible to infection from other viruses. However, scientists have identified numerous instances of viral hitchhikers that confer crucial benefits on their human hosts – from protection against disease to shaping important aspects of human evolution, such as the ability to digest starch.

Bacterial DNA

Mitochondria are separate small organelles found in every cell in your body. Their main job is to provide energy to the cell they are in. In fact, they are small ATP energy factories. In addition, they also play a role in other cellular processes such as signaling, cell differentiation and cell death, as well as cell cycle and cell growth control. To put it simply, not a single cell in your body would be alive without mitochondria and the bacterial DNA that controls them.

And what does that have to do with bacteria? As it turns out, the genomes in your mitochondria aren’t the same as the DNA in your cell’s nucleus (the DNA you inherited from your mom and dad). In fact, mitochondrial DNA is very different and shows considerable similarity to bacterial genomes. The theory is that somewhere in the past “a deal was struck.” Animal cells agreed to “build” bacteria into their cell structure – to provide a safe home for the bacteria – in return, the bacteria would perform a number of important jobs necessary for the maintenance of those cells. is that cool or what?

In fact, through the lens of the genome it contains, the mitochondrion is undisputedly of bacterial origin, originating from the bacterial strain α-Proteobacteria (Alphaproteobacteria). The members of the class Alphaproteobacteria are very diverse and share little in common. The only thing they have in common, like our mitochondria, is a now extinct common ancestor, the protomitochondrion.

Conclusion

When it comes to bacteria and viruses, we’re pretty much in an “I can’t live with them, I can’t live without them” scenario. Yes, small numbers can make us sick and even kill us. But a small number can improve our health and quality of life. In addition, some are not only useful, they are necessary for our existence. We simply wouldn’t be able to live without them – and we’ve barely mentioned the soil bacteria and viruses that are essential to the growth of our food.

However, for the purposes of our discussion, the most important thing is that we cannot avoid them or kill them all. We must find a way of living together – defending ourselves against the harmful while encouraging and nurturing the useful. To be clear, that doesn’t mean you no longer need to minimize contact with people who are highly infectious, or stop washing your hands after you’ve gone to the bathroom. Common sense still applies.

It just means that in the real world, unless you suffer from OCD or a similar condition, being a germphobia is simply an untenable position. There is no way to avoid all bacteria and viruses; it’s just not possible. Even if you locked yourself in a germ-free room for the rest of your life, you would still be bringing trillions and trillions upon trillions of viruses and bacteria into the room by virtue of your very existence — including your microbiome, your virome, and your DNA. In other words, you have to protect yourself against the bad guys and live with being submerged in a sea of ​​microbial entities (most of them neutral or even beneficial) for the rest of your life no matter what you do.