Microbiology — Viruses, Bacteria, and Fungi (Oh My!)

If biology is (broadly) the scientific study of life and living organisms, then microbiology is the study of microscopic organisms in particular. As Nature puts it:

“Microbiology is the study of microscopic organisms, such as bacteria, viruses, archaea, fungi and protozoa. This discipline includes fundamental research on the biochemistry, physiology, cell biology, ecology, evolution and clinical aspects of microorganisms, including the host response to these agents.”

In order to understand the world around us, like when we’re in the middle of a global pandemic, we need to have some basic knowledge. To that end let’s learn a bit about viruses and bacteria and how they operate. First let’s take a brief look at bacteria.


Scanning electron micrograph of methicillin-resistant Staphylococcus aureus bacteria (yellow) and a dead human white blood cell (colored red.)

Bacteria are microscopic, single-celled organisms. They are living creatures composed of just one cell containing a single loop of DNA. Since bacteria are alive (and highly resilient) they can live in almost any environment. We find bacteria in the soil, on mountains, in water, on skin and inside our bodies.

Bacteria can be either harmful or beneficial to human health. Most of the bacteria that resides on and in us are not harmful to us and in fact help our bodies function normally, e.g. in our gut (digestive tract). However, when we become infected with a harmful strain of bacteria, e.g. certain strains of Escherichia coli (E. coli), we become sick and our immune system has to mount a response.

Most bacteria reproduce by a process called binary fission. A single bacterium will split into two identical “daughter” cells which are clones of the “parent” cell. This can happen rapidly and each time it does, the number of bacterial cells doubles. If you run the numbers, a single bacterium doubling 19 times will become a bacterial colony of more than 1 million. Without an immune response or something like antibiotics, a bacterial infection can wreak havoc on its host.


Colorized transmission electron micrograph MERS virus particles (blue) found near the periphery of an infected VERO E6 cell (yellow).

Viruses on the other hand are not really alive at all. They don’t have any of the biological “machinery” required in order to survive on their own or even replicate. Viruses are essentially bits of genetic material (DNA or RNA) floating inside a protein layer. Therefore viruses need host cells from another organism like a dog or a human in order to do their job. That job is to replicate and they do this by invading a cell from the host and hijacking its biological machinery.

Once the virus has taken over the host cell, it goes about the business of replicating its genetic code, these new virus particles are coated with protein and then leave the host cell. Once the host cell’s machinery has been used up, the host cell typically dies and the now more numerous viral particles float around finding other host cells to infect and hijack.

Image: a virus’ genetic code (reddish-brown) inside the protein coat (blue). Enters the host cell area (yellow) and goes about replicating, then re-assembling and leaving the host cell.

The novel coronavirus and COVID-19

So, now that we know a bit about bacteria and viruses, let’s take a look specifically at this new (novel) coronavirus.

3D printing of the novel coronavirus

First why do we even call this the “novel” coronavirus? Because novel in this case means “not previously identified”. There are many viruses in the coronavirus family and none of them have caused the sort of situation we’re dealing with right now with COVID-19.

The novel coronavirus is classified as: severe acute respiratory syndrome coronavirus 2 or SARS-CoV-2. And the disease that it causes in humans is called COVID-19. So when reading or listening to news or information about the coronavirus keep that distinction in mind: SARS-CoV-2 or Coronavirus are referring to the virus itself. When someone gets sick because of the novel coronavirus, they’ve got COVID-19.

To recap so far, the virus known as SARS-CoV-2 is the cause of the current global pandemic. It’s a worldwide outbreak of a viral infection that is easily transmissible from person-to-person (highly contagious) and has a tendency in some people to cause severe illness or death. As of this writing the fatality rate globally of COVID-19 seems to be around 2% which equates to ~2,359,200 deaths so far.

In the U.S. alone there have been ~472,450 deaths so far and that number will continue to rise. In comparison to deaths from the influenza viruses, COVID-19 is a more serious threat to human health. The CDC estimates that in 2017–2018 there could have been around 61,000 deaths due to influenza. In 2018–2019 there was upwards of 34,000 deaths, and in the 2019–2020 flu season there were upwards of 22,000 deaths from influenza.

COVID-19 Conspiracy Theories

As a society we seem to have a troubled relationship with truth and facts these days. It’s important to reference our article about the reality of truth. If we can agree that facts exist and that there is not some massive cover-up going on related to COVID-19, then we have to come to these fatalities with a somber attitude and a decision to do our part to stop the spread of COVID-19.

The numbers don’t lie: COVID-19 is a much more deadly disease than the yearly flu and we should treat the global pandemic with the seriousness it deserves. In our next article we’re going to discuss face masks, how they slow the spread of a virus like the novel coronavirus, and get to the bottom of the controversy surrounding them.

To inform using reason, rationality, ethics, facts.