Mycelium, Hyphae, Spores, Oh My!

As hygienic, tidy college students, surely, we have never found our only slightly stale bread bedazzled with blue and green fuzz or our carpet (that hasn’t seen a vacuum since September) accented with a tasteful, mottled blemish. Right?

Photo by Helena Jacoba.

Enter fungi, the final member of microbiology’s big three! Both abundant and diverse, fungi range from the yeasts used in winemaking, to lichens that festoon trees, to mold on fossilized leftovers from the back of the fridge, and sometimes we even eat fungi on our Pizza!

And although we know upwards of 99,000 different fungal species, scientists find nearly 1200 new species each year! So, let’s touch on the criteria for a fungus.

Foremost, fungi is a eukaryote-exclusive club. To get in, you must show nucleus at the door. Accordingly, no one from the microbes we have been meeting and greeting with thus far even has a change! Viruses, for one, do not even have a cell, not to mention a nucleus, and as hinted by the designation “prokaryotic” or “before the kernel,” bacteria came before the nucleus. But since eukaryotic cells tend to be of larger volume and higher complexity, order is vital. To avoid losing enzymes within the vast cytoplasm or having a million and one different tasks going on simultaneously and interfering with one another (a metaphor for college life?), cells embraced a control freak approach. Each eukaryotic cell has everything for a specific process sorted and painstakingly packaged into tiny compartments or “organelles.”

Yet despite this additional nucleus and a handful of organelles, fungal cells tend to be fairly simple. Fungi have only 1% of the quantity of DNA we have and only 1.3 three times the largest known bacterial genome.

Fungi also value vintage and friends in high places! Not quite as ancient as bacteria, it is still estimated that fungi have been around for roughly 450 million years, about 25 million years before plants. Although an early species, fungi have actually been found to be more related to animals than to plants.  

And fungi have a few fun quirks and handy superpowers!

For one, a fungus does not digest its food within the cell, but rather, does so externally. The tiny molecules produced by this out-of-body digestion absorb into the cell via its walls.

So, how do fungi look?

Well, each genus and each species appears a bit different beneath a microscope, but the style that is simply all the rage among fungi is mycelium. Mycelium refers to the fungal body with branching thread-like protrusions. These ever-growing tentacles form from tube-like cells, known as hyphae.

But fungi also largely reproduce via spores. Spores, the survival kits of the microbial world, consist of only the necessities to whether a storm and pass on your genes: a cell or two carrying the genetic material of the fungus, some food, and any protective measures. Spores produced by fungi can withstand dry, hot environments before kickstarting growth upon reaching a favorable environment, but bacterial spores put them to shame with their incredible ability to withstand harsh environments. Yet, whereas these bacterial endospores serve merely as a survival mechanism, fungal spores predominately play a role in replication.

Photo by Nick Bramhall.

“Fruiting bodies” that produce these spores range from a variety of microscopic options to the shelf fungi and mushrooms we know so well! The diversity and unique nature of fungi (even when it has laid siege to your last slice of bread) is simply astounding!