Introduction to Botany 135: Magical Mushrooms and Mystical Molds

Introduction to the Fungi

The branch of biology that studies fungi (sing.=fungus) is called mycology, and for now I will only give you a brief introduction on the significance of fungi so that you will know something about them and you will have a more detailed introduction to what they are from the excellent BBC video, "The Rotten World About Us", on Thursday, followed by a formal lecture next week.

Fungi are among our most important organisms. One of the two most important function that they serve in nature can best be explained by a scene from "The Lion King" when Musfasa is trying to convey to baby Simba the meaning of the circle of life:

Mufasa: Everything you see exists together, in a delicate balance. As king, you need to understand that balance, and respect all the creatures-- from the crawling ant to the leaping antelope.

Simba: But, Dad, don't we eat the antelope?

Mufasa: Yes, Simba, but let me explain. When we die, our bodies become the grass. And the antelope eat the grass. And so we are all connected in the Great Circle of Life.

What Mufasa is trying to explain to Simba is that dead organic material is reduced into simple inorganic molecules that can then be recycled/utilized by plants. This concept can also be conveyed as a Food Web:

Other Ways That Fungi Impact Our Lives ( A Summary of Most of the Topics Covered This Semester)

Fungi impact our lives everyday and have played a role in numerous, important, historical events. They have impact on the world around us as recyclers, which I have already mentioned, rotters (same as recyclers), pathogens and symbionts. I will summarize some examples and tell you about specific fungi and what they do, but will not say anything about the mechanism of how the fungi are able to carry out these activities. For example, you all know about some fungi being able to rot wood, but you do not know how they are able to do this. We will cover the "how" part, next week.

Fungi have played an important role throughout history, in every culture of the world. In the introduction of Mushroom, Molds and Miracles, Kavaler (1965) describes the role of fungi in the fall of the Roman Empire. The Roman Empire became a significant, world power by approximately 264 B.C. and would eventually rule the regions bordering the Mediterranean Sea, which included England, parts of Europe, the Middle East and Africa. Their vast empire would rule for 500 years before disintegration of the economy and numerous invasions by barbarian tribes led to the eventual fall of Rome. One explanation as to Rome’s financial decline came about following a period of abnormally heavy rainfall in the Mediterranean. The rain was initially a blessing that led to an increased yield in their wheat crop. However, with the excess in rainfall there also came the proliferation of various types of pathogenic fungi, such as "rusts", "smuts" "ergot", etc., which laid waste to the wheat fields. The Romans observed on their crops the orange, black or white powdery masses of spores, which were responsible for starting and further perpetuating the diseases, the rotted roots beneath the soil, the fallen plants due to the weakening of the stems and darkened leaves from various diseases. Even the very kernel of the grains were destroyed and replaced by a hard, black, boat-shaped structures called ergots. These diseases destroyed most of their crops. After many years of continued crop failures, hunger spread, leading to unrest among the Roman people. This unrest, caused by fungi, was one factor that led to the eventual fall of the Roman Empire. Other events contributed to the decline of Rome, but are not relevant to this course, but if you wish to read a summary of the decline of Rome, click here.

I will digress here to emphasize an important point that often occurs when scientists study history. Richard Rathman, of the History Department, here at the University of Hawaii pointed out to me that when historians study history they try to interpret and explain the past by examining a series of interconnected events as was summarized above. However, often when scientists try to play the role of historians, they attempt to “predict” what has happened, often attributing a single event or trend to a single phenomenon. For example, in the fall of the Roman Empire, a scientist reading about the various fungal diseases of plants that led to unrest within Rome may attribute the decline of Rome to this event. However, an historian would see this as one of many events, all contributing to some degree, to the fall of Rome. I will attempt to at least summarize all events involved, but emphasize the role of fungi when discussing historical events.

Although fungi played such an important role in the decline of the Roman Empire, the actual causes of the crop failure were unknown to the Roman. It was not until the 19th. Century that fungi as well as other micoorganisms would even be recognized as the cause of diseases. As with many unexplained phenomenon, in many cultures, the Romans attributed their crop failures to the wrath of their gods. There are many other instances of fungi playing significant roles in recent historical events, such as the potato famine, in Ireland, during the mid 1850's and some that are very ancient that have been recorded in the Bible.

Fungi, however, should not only be looked upon as negative organisms because they contribute tremendously to our well being. In 1928, Alexander Fleming, a British bacteriologist, upon examining his bacterial cultures that he had recently started noticed that one of his cultures had become contaminated with a fungus. It was a common fungus that had started from spores that had blown into his culture and somehow succeeded in killing the bacteria. This inadvertent contamination led to one of the most significant discoveries of the 20th. Century. Those of you who have had a course in biology probably know that this led Fleming to his discovery of the "wonder drug" that we know as penicillin, and with it, a new era in the treatment of infectious bacterial diseases began. The discovery of penicillin would lead to the search and discovery of numerous other antibiotics.

The fungi with which most people are familiar are the mushrooms, but many people in Western Cultures probably do not even know that mushrooms are fungi. The reason for the lack of familiarity with mushrooms is that our society, as a whole, is mycophobic. This means that they dislike, fear or even hate mushrooms. Why is our society mycophobic? That is something that we will discuss at a later time. However, even though we live in a mycophobic society, almost every state in this country has many societies, clubs, groups, etc. who are mushroom lovers and are dedicated to the collecting, identifying and eating (mycophagy) of wild mushrooms, i.e. non-cultivated mushrooms. What kinds of people belong to these clubs? They come from all walks of life. There are white-collar people such as business people, doctors and lawyers, as well as blue-collar workers such as carpenters, auto mechanics and custodians. While their backgrounds are diverse, these societies meet to collect and later cook up what they have collected, and talk about mushrooms. As an undergraduate living in San Francisco, I attended several meetings of the San Francisco Mycological Society and was quite impressed with how knowledgeable the members were when talking about mushrooms and also the passion that many members seem to have for mushrooms as they spoke to each other. Some members, I have to confess, were passionate to the point of being somewhat eccentric. I recall one meeting where I met a member who came to a meeting with a shirt, tie, and even shoes that were decorated with mushrooms. I don’t know where he got the shirt and tie, but he obviously painted the mushrooms on the shoes himself.

Even Hawai‘i, probably one of the few places in this country that does not have a mushroom hunters club and can even be interpreted as being mycophobic, has a mushroom that is a local favorite called that is often eaten called the pepieao-akua (often just pepieao). Thus, many species of mushrooms are identified with specific cultures.

While many species of wild mushrooms are collected for consumption, relatively few species of mushrooms are cultivated as food. Despite this mushroom cultivation occurs worldwide and is a multi-billion dollar enterprise. While this is the case, it should be pointed out here that although mushrooms may add flavor to food and is a favorite ingredient, they cannot play a major role in our diet because they are 99% water. However, fungi can still play a very significant role in the production of some of our important food products and beverages. When you're making bread, you put into the oven a pretty dense, heavy lump of dough, but after baking the dough, a fluffy loaf of bread comes out. The juice that is pressed from grapes is transformed into wine, sheep's' milk cheese is made into tart Roquefort cheese, a foul smelling rye mash becomes whisky, and malted grain is made into beer. The above products would not be possible without the activities of fungi.

The most controversial of fungal products are the psychoactive drugs. The most famous being LSD-25 and psilocybin. In today's society, these drugs are taken for recreational purposes. However, psilocybin, which is often ingested by consuming mushrooms from the genus Psilocybe, was/is also used by Native American Indian in some of their religious ceremonies and is regarded as being sacred. The more familiar of the two drugs is probably LSD-25. The intended purpose of this drug was for the treatment of certain forms of mental disorders. This was also true for psilocybin. However, because of their abuse as recreational drugs and the harm that has come about through this type of usage, possession of these drugs is no longer legal.

Although many species of fungi are responsible for producing some of our foods, some are also responsible for taking the food from our mouths. The reason for this is that any food that we can consume can also be consumed by various fungi. The annual quantity of food destroyed by fungi is very high. For example, when you're shipping fresh fruit by railroad cars, let us say that there are 25 carloads, the equivalent of 1 carload will arrive rotten and must be disposed of. There are a number of fungi that derive their nutrition from stored food material. Fungi can potentially contaminate many of the food that we leave out at room temperature. This is the reason why we refrigerate perishable food. However, as you probably all know contamination of food by fungi can still occur when food is refrigerated. The reason for this is that fungi can survive and even thrive in refrigerators. The act of refrigerating food usually will only slow the process of fungal contamination. The same holds true for food that is stored in an extremely dry environment. Dried grains are commonly stored in large silos where it is too dry to be contaminated by most fungi, but a handful of species can still grow in this type of environment.

Stored food is not the only commercial product that can be infected with fungi. Wood and wood products are commonly rotted by fungi, and numerous other commercial products can also be ruined by fungi. However, you may not attribute damage that occur in many commercial products to fungi. For example, how many of you have ever noticed that a few years after a house has been painted that paint may begin to blister, turn a different color and eventually peel off the surface? You automatically assume that this was all caused by environmental factors such as rain, wind and sunlight or even neglect, which may be the case, but another possible and even probable reason is that a fungus is eating away at your paint. Yes, fungi can “eat” the paint that is meant to protect your house from the environment. Even material made from glass and rubber is not safe and can be damaged by fungi. Fungi may even etch the lens of your camera, telescope, eye-glasses, etc, and the rubber in your electrical insulation can become damaged.

From our first story you know that some fungi can cause various diseases on plants. Although fewer in number, fungi can also cause diseases in animals. At one time or another, some of you may have contracted fungal infections such as athlete's foot and ringworms. While not pleasant, nobody dies from these types of infections. However, some fungal diseases such as Valley Fever and Histoplasmosis may be fatal. Regardless of the type of fungal diseases that you have contracted, they are usually difficult to treat.

So you can see that in the immediate world around us it would appear that the harm done by fungi would seem to be about in balanced with the good, but there is one thing that I only just mentioned, above, that makes fungi essential to all life on this planet. What function might they have that would make them so important? Each living organism, from the simplest one-celled life forms to multicellular, complex organisms such as ourselves, grow, reproduce and eventually die. We are then returned to the earth through the process of decomposition, by fungi and bacteria. In obtaining food from dead organisms, they literally reverse the life process. Another words, when an organism is growing it takes in food and uses that food to build complex compounds, i.e., proteins, carbohydrates, fats, etc. from the simpler chemicals, which results in the growth of an organism. The act of decomposition by fungi and bacteria reverse this process and breaks them down again, into various simple compounds composed of carbon, nitrogen, sulfur, phosphorous, etc., which are returned to the soil to maintain its fertility. These compounds can then be utilized by plants for their own growth processes. Animals then consume plants, which are then consume by other animals, until each in their turn become food for the fungi and bacteria again. Thus, without fungi, as well as bacteria, this "recycling of nutrients" in the soil would not be possible, and life on this planet could not exist. For this reason fungi and bacteria must have been one of the first organisms, although probably not the first, to exist on this planet. When the first Voyager mission was launched to Mars, in the 1970's, one of its objectives was to determine if life exists on Mars. Most of these tests involved taking soil samples. The reason for this is simple, if life did evolve on Mars, fungi (as well as bacteria) must also have evolved, because in order for life to continue, some sort of recycling organisms must exist. A camera was also launched with the probe on the off chance that there might be large animals walking around Mars, but none were seen. Thus, the existence of "little green men" on Mars, at least for now, is only something that exists in the imagination of science fiction writers.

Finally, let's look at the number of fungi relative to other organisms. There are, presently, approximately 1.5 million species of organisms that biologists have identified and thousands of species are added each year. It is estimated that the total biota on this planet is between 5-30 million species (Campbell, et al. 1996). Of this total, approximately 100,000 species are estimated to be fungi, a relatively small percentage of the total biota. However, many of these species are so wide-spread and the dominant organisms in many habitats that they must be considered one of the most successful organisms, in the world. Clyde Christensen, a former plant pathologist from the University of Minnesota stated in his book "The Molds and Man" that fungi may not inherit the Earth, but they do control a great deal of it. That's not quite true! They have, in fact, inherited the Earth on at least one occasion, and possibly more. An indication as to how successful fungi can become was found in the fossil records by Visscher et al (1996). It has long been known that about 250 million years ago, during what is known as the Permian Period, the largest mass extinction ever recorded occurred. The cause of this catastrophe is not known, but it has been estimated that approximately 90 percent of marine animals became extinct during this period. The emphasis was placed on extinction of marine animals because the oceans tend to be a more stable and uniform environment than the terrestrial. Thus, if most of the marine organisms became extinct during this period, extinction of the terrestrial life must have been even greater. Paleobiologists, biologists that study fossils, previously believed that only plants had gotten through this crisis with relatively few losses. However, examination by Visscher et al (1996) of plant fossils, from this period, indicated that plants suffered along with the rest of the world's biota. Plants from this period were found to have been fossilized with massive amounts of fungi. Normally, there is little evidence of fungi in the fossil records and seldom are they associated with plants, but because so many plants died off at this time, a great proliferation of fungi and bacteria occurred due to the sudden increase in dead organic material, much of which was fossilized. For this brief period in time, fungi and bacteria were the dominant life forms on Earth! A summary of this article, by Richard Monastersky, can be found in the March 1996 issue of Science News.

We will discuss the topics that I just summarized in more details throughout the semester. Many of these topics represent different disciplines within mycology. These include:

Plant Pathology: The discipline that studies plants and their diseases. Organisms involved in diseases of plants include bacteria, viruses and insects, as well.

Deterioration Mycology: The discipline that studies the harmful effects that fungi cause on commercial products.

Medical Mycology: The discipline that studies the diseases of animals, including man.

Aesthetic Mycology: The study of fungi for intellectual interest and curiosity.

Mycological Terms

mycophobic: Having a fear or aversion of fungi.

recyclers: Referring to the ability of some fungi (and bacteria) to extract and reuse dead organic material

pathogens: An agent that causes disease, especially a living microorganism such as a bacterium or fungus.

symbionts: A close organisms, between two organisms that is mutally benefitial to both organisms.

rusts: in plant pathology, name for a fungus of the order Uredinales and for the plant diseases such fungi cause. Rusts form reddish patches of spores on their hosts.

smuts: Plant diseases, especially of cereal grasses, caused by parasitic fungi of the order Ustilaginales that form black, powdery masses of spores on the affected parts.

ergot: Disease of rye and other cereals caused by a fungus (Claviceps purpurea), which appears among the grains of rye as dark purple structures. The ergots, which resemble rye seeds, contain certain active substances (alkaloids) that are poisonous.

spores: A small, usually one to several-celled reproductive body produced by certain bacteria, fungi, algae, and nonflowering plants that is capable of growing into a new organism.

penicillin: A group of broad-spectrum antibiotic drugs obtained from molds of the genus Penicillium or produced synthetically, most active against gram-positive bacteria and used in the treatment of various infections and diseases.

mushroom: The various fleshy fungi characteristically having an umbrella-shaped cap borne on a stalk. Term usually refer to the edible species such as Agaricus bisporus, the common supermarket mushroom.

mycophagy: Consumption of fungi, usually referring to mushrooms.

Literature Cited and Further Readings

Kavaler, L. 1965. Mushrooms, Molds, and Miracles: The Strange Realm of Fungi. John Day Co., New York, NY. 318p.

Visscher, H., H. Brinkhuis, D.L. Dilcher, W.C. Elsik, Y. Eshet, C.V. Looy, M.R. Rampino, and A. Traverse. 1996. The terminal Paleozoic fungal event: Evidence of terrestrial ecosystem destabilization and collapse. Proc. Natl. Acad. Sci. USA, 93:2155-2158.

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