Bacteria, viruses and various parasites have troubled humanity throughout its history. You don’t have to go far for examples; the outbreak of coronavirus in 2020 is a vivid confirmation of this. But microorganisms also changed their lives (and not always for the worse) and influenced our evolution. For example, parasites helped our immune system find the necessary stimulus and become working, and the bacteria completely determined the rules of life on this planet. Sometimes it seems that we humans are just toys in their hands. And here a quite reasonable question arises: how, in fact, are microbes, bacteria and viruses different?
What are microbes
Microbes are microscopic organisms that live in the environment. Microbes can live not only in the earth, in water or air, but also even inside plants, animals, and humans.
Most microbes are harmless to humans, but there are those that, when ingested, cause various diseases and infections. Depending on the structure and influence on a person, several types of microbes are distinguished, including the most common:
In other words, microbes are all living microorganisms that surround us. And already they are divided into types. Most often in everyday life, bacteria are meant by microbes, that is, they are equated with each other. In theory, this can be done (we call oranges fruits), but bacteria are a separate class of microbes.
What are bacteria
Bacteria are unicellular microorganisms (microbes) that do not have a formed cell nucleus. This is the most common type of living organism that lives on Earth.
Bacteria are not only “bad”, which cause infections and subsequent diseases. Many bacteria are an integral part of human life, without them we simply could not have lived. For example, at this moment, when you read this text, you benefit from the work of bacteria. From the oxygen you inhale to the nutrients your stomach extracts from food, you need to thank the bacteria for their prosperity on this planet. In our body, microorganisms, including bacteria, are about ten times more than our own cells.
There are about 39 trillion bacteria in the human body.
Because of this, many joke that we are probably more microbes than people. And to a certain extent this is true.
Why are bacteria so unique? Everything in the world consists of cells – these are the building blocks of life, the tissues of our body, the foot of your cat, and the tree that grows outside the window are made up of them. Such cells have a nucleus and are called eukaryotes. Bacteria do not have nuclei, and their genetic material (DNA) floats freely inside the cell. They have other methods of reproduction and transmission of genetic material. Bacteria are considered prokaryotes.
What is the difference between bacteria and microbes
To isolate bacteria among microbes, you need to make sure that we are dealing with a unicellular, non-nuclear organism. This is done by specialists – microbiologists.
Microbiology – the science of all types of microbes, including bacteria, fungi, viruses, and protozoa – allows you to distinguish bacteria from their microbial brothers.
Unlike other microbes, bacteria are categorized according to criteria that apply only to them:
- Survival in an oxygen-free environment;
- Form of bacteria: sticks (bacillus), circles (cocci) or spirals (spirillum);
- Do bacteria have an external protective membrane that prevents staining of the cell’s insides;
- How bacteria move (many bacteria have flagella that allow them to move).
Most bacteria are useful, and they are often used in industry, using one of their brightest qualities: they can eat what a person cannot. Bacteria have evolved to absorb all types of products, from oil spills and by-products of nuclear decay to human waste and decomposition products.
It is the bacteria that cause the unpleasant odor that appears in the wastebasket – they process the remnants of food and emit their own gaseous by-products. You can also blame the bacteria for causing these awkward moments when you yourself emit gas, or if you have bad breath.
How old are bacteria? Scientists still cannot answer this question. Presumably it was they who produced some of the oldest fossils, which are 3.5 billion years old. How many bacteria existed before that is hard to imagine. The fact is that some bacteria can withstand extreme conditions, when either it is very hot or cold, or there are no nutrients and chemicals that we usually associate with life. They can exist almost forever.
Despite the presence of many beneficial properties, some bacteria can be pathogenic, that is, cause diseases and illnesses. For example, it was the bacteria that caused the plague: the plague bacillus Yersinia pestis killed over 100 million people. It is the bacteria that are responsible for staph infections. Moreover, they differ in their ability to develop antibiotic resistance. So the bacteria that cause anthrax, pneumonia, meningitis, cholera, salmonellosis, tonsillitis, and other diseases are always dangerous for us.
Most harmful bacteria can be destroyed with antibiotics, but if you stop treatment prematurely, those bacteria that survive will develop resistance to the drug and remain, waiting for the next chance. Therefore, doctors recommend completing the course of antibiotics to the end.
Bacteria can also be used as biological weapons. For example, it was with their help that epidemics of anthrax were artificially arranged at one time. Therefore, do not underestimate these unicellular organisms. In fact, we are entirely in their power.
Bacteria of the species Halomonas titanicae are right now corroding the metal leftover from the wreck of the Titanic ship. Imagine what they are capable of.
What is a virus?
But if bacteria can be so dangerous, why are we more afraid of viruses than bacteria? Unlike bacteria, viruses can infect not only complex living organisms, but … bacteria themselves.
A virus is a non-cellular infectious organism that can only live inside living cells.
Viruses can infect all organisms, from plants and animals to bacteria and archaea. At the same time, these are parasites, that is, they cannot survive on their own, unlike bacteria. Viruses use cells (humans, plants, animals) to live. If the virus appears outside the cell, it exists in the form of a viral particle, but it can also be dangerous: any contact with a living cell can activate it, give it food. At the same time, the virus cannot reproduce by the cellular method – it creates its copies only with the help of living cells.
When the virus is near the cell, it attaches to it, creating a connection between the viral envelope proteins and receptors on the surface of the living cell. Through this connection, the virus enters the cell and releases its genetic material. And there it’s the small business – to create your own copies and populate new cells in the same way.
What is the difference between bacteria and viruses
The peculiarity of viruses is that they can change at a non-genetic level. These changes lead to their mutations in living organisms; in the case of coronavirus, for example, the virus could only infect animals (bats) at first, and then change the DNA so much that it was able to infect human cells.
Viruses can be more dangerous than bacteria because of their ability to change at the genetic level. That is how the viruses of influenza, immunodeficiency, hepatitis A and C appeared. But if the viruses are parasites and cannot exist without living organisms, did they somehow appear? According to one hypothesis, viruses once (billions of years ago) were small bacteria that parasitized on larger living organisms. Later, these bacteria simplified, having lost functions that are not needed for a parasitic lifestyle. Evidence of this hypothesis is the existence of rickettsia and chlamydia. So viruses are “pumped” bacteria, which nevertheless cannot live on their own.
The size of the viral particle is about 100 times smaller than the size of the bacteria, and the shape varies from just spiral to more complex structures. One of their forms is like a crown. It is she who is the very coronavirus.
Which is more dangerous – bacteria or viruses?
Viruses can obviously do much more harm than bacteria. For the simple reason that there are no “good” viruses, as is the case with bacteria (like bifidobacteria and lactobacilli, which allow us to digest food). In addition, many viruses differ simply ugly behavior – they can exist for years inside the cell, causing chronic diseases. Herpes can be an example of such viruses.
From the whole three – microbes, bacteria, and viruses, it turns out that the most dangerous are microbes since they include all microorganisms: both beneficial and extremely harmful to the body. Now scientists are working to extract as much benefit as possible from the “good” bacteria: the possibilities of introducing certain microbes and bacteria into the human body, which can give certain advantages, are being actively studied. For example, destroy tumors. By the way, it was because of the bacteria that penicillin was accidentally discovered – an antibiotic that saved many lives.