Every human has approximately 39 trillion microbial cells living on and inside us. I learned this as part of a compulsory first-year class, and alongside all the typical challenges of starting university, I was one step closer to an identity crisis. Does knowing I provide a home to 39 trillion organisms fuel a God complex or does it add to my insignificance, knowing that the world is now infinitely bigger than I previously thought? Not only am I only one of billions of humans, but each of those humans has trillions of microbes.
Every human has approximately 30 trillion human cells. Technically, we are more microbe than human. Luckily, human cells are a lot bigger, so by weight we are still more human than microbe, but I still feel a little outnumbered.
Since learning about my microbiota, I’ve resolved to think of myself as a house. Or rather an expansive hotel with 39 trillion tenants each living in different rooms in my body and diligently performing tasks to help me survive. Throughout the course, I began to familiarise myself with just a tiny fraction of these tenants, Staphylococcus aureus who live on my skin and are tolerant to the high salty conditions of sweat, Entamoeba gingivalis who inhabit my mouth, Bifidobacterium bifidum who help my gut to break down food, and even Lactobacillus that live in my urinary tract and help prevent UTIs. There really are microbes all the way down!
Most of our human microbiota are acquired at birth or shortly after. This means my microbial tenants (and their ancestors) have been with me all my life. This whole time, they have been helping me function and survive without me being aware of their presence at all.
I learned about how my dutiful microbiota helps shape and train my immune response to different pathogens. My microbes help to protect against infections by competing with pathogens for resources and space within the body.
However, despite my microbiota’s efforts, some sickness is unavoidable and each time a new traveler arrives at my microbe hotel, the residents have to battle it out.
I thought about my body fighting off these pathogens, and became perplexed by how my body (with the assistance of vaccines) knew what to do without me telling them a thing. Helper T cells quickly activated lymphocytes, producing antibodies to target the specific antigens. Everything works in tandem, while my body languishes in bed binge-watching Netflix. I wish I could write a thank you card to my immune system for helping me recover; instead, some Immuneboost vitamins will have to do.
It’s safe to say that this class changed the way I think about the world and myself completely. But perhaps the most shocking fact of all is that, even though for a whole semester we studied hundreds of different microbes, this is only the surface of microbiology. Less than 1% of microbes can be studied in laboratory conditions, leaving me and my classmates almost entirely unaware of the other 99% of microbes.
I never took another microbiology class, and now that I am in my third year, I doubt I ever will. But evidently, I still think about that class a lot. Every time I ride an escalator, blow my nose, or really do anything at all, my microbes are with me and my awareness of them makes me feel some kind of way.
