the "one gene one enzyme" theory in Neurospora won Beadle and Tatum the Nobel prize for Physiology or Medicine in 1958. Fungi are also important genetic tools, e.g. Fungi are used to study metabolite pathways, for studying growth, development, and differentiation, for determining mechanisms of cell division and development, and for microbial assays of vitamins and amino acids. Since they are eukaryotes and more closely related to animals, their study is more applicable to human problems than is the study of bacteria. They are easily cultured, occupy little space, multiply rapidly, and have a short life cycle. Fungi are also important experimental organisms. There are likely many potential uses that have not yet been explored. Stone washed jeans are softened by Tricboderma species. Some gourmet cheeses such as Roquefort and other blue cheeses, brie and camembert are fermented with certain Penicillium species. citric acid in cola and other soda pop products is produced by an Aspergillus species. Many organic acids are commercially produced with fungi- e.g. Steroids and hormones- and even birth control pills - are commercially produced by various fungi. The immunosuppressive anti-rejection transplant drug cyclosporin is produced by the mitosporic fungus Tolypocladium inflatum. Antibiotics such as penicillin and cephalosporin are produced by fungi. Yeasts have been used for baking and brewing for many millennia. Of course, there are many edible mushrooms, both cultivated and collected from the wild. There are many ways in which people have learned to exploit fungi. In this age of immunosuppression, previously innocuous fungi are causing more and more human disease. They can destroy almost every kind of manufactured good- with the exception of some plastics and some pesticides. They often cause rot and contamination of foods - you probably have something green and moldy in theīack of your refrigerator right now. Fungi can cause human disease, either directly or through their toxins, including mycotoxins and mushroom poisons. On the other hand, many fungi are detrimental, inciting a large number of plant diseases, resulting in the loss of billions of dollars worth of economic crops each year, and an increasing number of animal diseases, including many human maladies. Fungi also form mutualistic associations with algae and cyanobacteria in the dual organisms known as lichens. Fungi are also important mutualists over 90% of plants in nature have mycorrhizae, associations of their roots with fungi, which help to scavenge essential minerals from nutrient poor soils. Thus, many are excellent scavengers in nature, breaking down dead animal and vegetable material into simpler compounds that become available to other members of the ecosystem. Since all fungi are heterotrophic, they rely on organic material, either living or dead, as a source of energy. Fungi have many different kinds of associations with other organisms, both living and dead. They are a vital part of the links in the food web as decomposers and pathogens and are important in grassland and forest ecosystems alike. However fungi play very important roles in the ecosystem. Many ecologists do not even think about fungi when doing their experiments or observations. For example, more than 90% of fungal species have never been screened for antibiotics or other useful compounds. The study of fungi has increased exponentially in the past 100 years, but they are still being ignored or neglected in many fields of study. Fungi affect human lives in many and varied ways, so it is important to know something about fungal biology in order to be able to control or exploit them for our own purposes. Often they don't know what a mycologist is, but when I tell them, the next question is "why?" Why study fungi? When someone mentions "fungi" you may think immediately of mushrooms on pizza or maybe moldy food in your refrigerator or the fungus growing on your t o e s - But in fact fungi are everywhere and affect our lives every day, from mushrooms to industrially important products to plant helpers to plant pathogens to human diseases. Fungi: The threads that keep ecosystems together When people ask what I do for a living, and I tell them I'm a mycologist, they usually react with surprise.