Ancient Egyptians Know What's Up!

I assume everyone has had a scratch or even worse: the deadly papercut, before. Before Band-Aids and Neosporin, the ancient Egyptians’ go-to for healing the nefarious papyrus-cut was some good old mold. According to a publication in the Mycologist, Imhokep, a legendary Egyptian healer (later worshiped as a god of medicine), used mashed up moldy bread to treat skin wounds. While this might sound crazy, or at least counterintuitive when you consider ringworm and other fungal infections, it is actually way ahead of its time.

Named from the Latin word for paintbrush, Penicillium notatum (aka P. chrysogenum) is quite the artist. A fungus with the mycelium, hyphae, spores, and so on, it is particularly fond of decorating bread with some blue, green, and sometimes even yellow spores. And since Penicillium notatum is not prone to infecting us, although some can have allergic reactions to its spores, it is often used for student microbiology labs here at Penn State! In my Microbiology 203 lab class, our first experiment investigated ideal growing conditions for P. notatum. So, I speak from experience, when I say that this fungus is partial to room temperature and damp conditions!

 

Photo of Penicillium by AJC1.

But as you can guess from Penicillium’s spoiler of a genus name, we have this pesky, bread-poaching fungus to thank for one of the most important discoveries in microbiology. Ever.

What do you get when you cross a two-week vacation and a messy scientist? Apparently, the advent of antibiotics.

Alexander Fleming, a not-so-tidy lab technician, neglected to clean his lab bench before taking a two-week leave, and when he returned he noticed a bunch of white fuzz in one of his Staphylococcus cultures. Of course, this was our friendly neighborhood bread mold, Penicillium notatum! It was not P. notatum that made Fleming take another look; rather, it was how it seemed almost as if the fungus kept the Staph bacteria at arm’s length, not allowing it to come near! Plus, when Fleming took a closer look with a microscope, the bacteria seemed to be “lysing” or dying.

In the end, Fleming found that P. notatum secreted a substance able to kill Staph and a slew of other bacterial species. Upon isolating and examining the properties of this secretion, Fleming promptly passed it off to Howard Florey and Ernst Boris to tackle the impossible task of purifying it as a stable compound. And some 10-20 years later, we had Penicillin, the world’s first, and now the most widely used, antibiotic!

Ironically enough, in his initial publication about Penicillin, Fleming didn’t even mention using it for therapeutics! Instead, he focused on its ability to help identify bacteria since it could inhibit some bacteria but not others.

Speaking of inhibition, how precisely does Penicillin play bacteria’s kryptonite?

Penicillin’s claim to fame lies in its special “beta-lactam” ring of three carbons and one nitrogen atom. This ring is the lock pick to a bacterium’s ability to build cell wall. The beta-lactam ring grabs onto a specific type of transpeptidase (called Penicillin-binding proteins or PBPs), the enzyme that weaves strands of cell wall material together. Penicillin then becomes clingy and controlling, keeping a transpeptidase from binding to other molecules and doing its job, and allowing new cell wall to unravel.

But Penicillin is not only the granddaddy of antibiotics, but also a more select class known as Beta-lactam Antibiotics. The Beta-lactam club includes other antibiotic celebrities like methicillin, ampicillin, and amoxicillin!

And since our cells oh-so-conveniently missed the boat on getting a cell wall, Penicillin can keep who is the rival bacteria and who is the home team straight!

But why does bread mold even produce this medical wonder child?

Penicillium notatum evidently does not see anything wrong with playing dirty! When there is nutrients and space on the line, why not take out the competition? Penicillium notatum might be a friend to us, but not so much to the bacteria it is contending with!

It sounds like the ancient Egyptians were actually on the right track!