Tortillas and Grapes: the nose knows

“Huh.”  Contemplating, that’s all I said when I uncovered the SBA plate. I was overwhelmed by a smell I knew. It was a smell that in all honesty started to make me hungry. It was the smell of tortilla chips. It was Pseudomonas.

Microbiology is the science that deals with microorganism.  It’s an invisible world brought to life where color explodes and smells are amplified.

As a second round of plastics begins here in Benin, the ORs are gearing up for more burn contracture releases and lipoma removals while the lab readies to be hurled into this world of colorful and potent, invisible life.


©2016 Mercy Ships Photo Credit Justine Forrest; Dyllan with Grandmother in B Ward


In the Africa Mercy laboratory we are concerned mainly about aerobic bacteria and there are numerous steps we take to identify all the characters present.  One technique, unofficially, is smell.

So just for fun, here is a list of what my nose knows…


Pseudomonas aeruginosa: grapes or tortilla chips.

This has always perplexed me. In my mind these two things are nothing alike. Since I was 17 years old and taking my first micro class with Mrs. McBrien (shout out!!) I have always smelled grapes. The rich, sugary, children’s Tylenol, icy push-pop on a summer day, artificial grape smell. It overwhelms the incubator when it is growing.

As mentioned earlier, the other day I finally smelled the tortilla chips. I am now convinced that it is not a people smell one or the other sort of thing, but that different strains have different smells. The less colorful, not as impressive strains smell like a boring bowl of corn chips while the iridescent, multicolor strains take on the artificial grape smell – maybe



Proteus species: sweaty socks or chocolate cake.

Again, how is this possible? What kind of chocolate cake are people eating that smells like a boy’s locker room? With this one my theory is the longer you work in micro the less vile some things become, so after a year or so the musky scent of Proteus does begin to smell like a dark chocolate cake. It’s weird, I know, but trust me it does.


Strep viridans and Group F Strep: butter.

This is another one to make your mouth water. When you get a pure plate of Strep viridans, you may as well have walked into a movie theater it smells so much like freshly popped popcorn. You can almost feel the grease as you swipe a colony for more testing.


E. coli: mothballs.

Take a walk through grandma’s closest and you are there. It is that strong, chemical smell that burns your nostrils.


Eikinella corrodens: bleach.clorox

Plain and simple, there is no arguing, everyone is in agreement that this one smells like a bottle of Clorox.


Last, but not least,

Staph aureus: Staph aureus.

I’m not sure there is another way to describe it.  S. aureus has a very specific spell but it does not smell like anything else.  Work long enough in a micro lab and you too will know what this unique smell is, as well as all the others.

Thanks for joining me on this journey into the incubator.