Why Fungi Represent the Circle of Life

People look at me funny when I say that fungi are the circle of life.  Comments range from the disinterested, “Yeah, right.   Whatever,” to the challenging “What are you talking about?”

Well, here is what I am talking about. 

Fungi, particularly microfungi, the kind you need a microscope to see, are critical to all living systems.  In school, we learn fungi are “decomposers,” and we assume they come up out of the soil to eat dead plants, dead dogs, and the food that got pushed to the back of the refrigerator. Unfortunately, we rarely stop long enough to wonder how the fungi got from the soil to the back of the refrigerator.   Maybe concerns that we still have dirt under our fingernails makes us reluctant to consider that question.  But the fungi are probably in your refrigerator because you put them there.

You see, fungi in nature are associated with many kinds of living cells.   In plants, we find them associated with seeds, roots, stems, and leaves.  We even find them in the endosperm, surrounding the embryos of future seedlings, and we find them inside individual cells[i]! So, those fungi aren’t coming from the dirt under your fingernails.  They are coming from the food itself.  They are coming from the leaves (think lettuce) the roots (think carrots) the stems (think celery) and the cheeses, meats and eggs[ii] that you eat.  They aren’t coming from the milk though.  Milk has been pasteurized.   

At one time, scientists thought that any fungus living inside the cells or tissues of a plant or animal was causing disease.  But today we know that most fungal associations are part of a healthy state.   In fact, when you rigorously remove all the fungi from plants (as can be achieved with certain fungicides), you kill the plant as well. 

 A lot of people don’t know understand all this yet, and not many people know how to find the in plant cells, so if someone tries to sell you a “fungus free” plant, you better ask them to show you the metagenomic analysis, or learn how to separate mycosomes[iii].  If your plant is truly fungus free, I assure you it is also dead. 

   

Growing pools of data from the human microbiome suggest that our own cells may be as heavily populated with fungi as the cells of the plants (and animals) we eat.  Meanwhile, evolutionary biologists tell us that all plants and animals descended from communities of symbiotic microbes[iv].  So what are all these fungi and other microbes doing?  And how do you associate them with a circle of life?

Well, your teachers were right about one thing.  Fungi are decomposers.  They do take nutrients that are no longer being used and move them to places where they are needed.   But that isn’t all they do.  When fungi associate with plants and animals, the fungi can donate water, minerals, or nutrients in exchange for the energy, the calories,  they need to grow.   Fungi can dissolve minerals like phosphorus from rocks and soil, converting it to forms that plants can use for food.  They even make chemicals, like alkaloids and terpenes, that protect plants from insects and pests.  You see, like a network of free market entrepreneurs, fungi excel at connecting consumers to the resources they need.

So why are do I call them the circle of life?  Well think about it.   The same fungal colonies that connect the tree to the soil can colonize your skin when you handle fruit from the tree.  They can colonize your intestines when you eat the fruit.   These fungi can then work to  help you to cycle nutrients, or they can be passed from you to those you come in contact with. 

This connectivity that fungi form between humans and their environment allows all of us to share energy and nutrients with the earth itself and with everything that lives on it.  And because this sharing brings good things our way, things like minerals, nutrients, and water that we need to survive, it is fair to consider this fungal-mediated cycle as “the circle of life”.

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[i] (Endophyte microbiome diversity in microprpagated Atriplex canescens and Atriplex torreyi var griffithsii, 2011)

[ii] (Novel Symbiotic Protoplasts Formed by Endophytic Fungi Explain Their Hidden Existence, Lifestyle Switching, and Diversity within the Plant Kingdom.)

[iii] (Novel Symbiotic Protoplasts Formed by Endophytic Fungi Explain Their Hidden Existence, Lifestyle Switching, and Diversity within the Plant Kingdom.)

[iv] (Margulis, 1999)