The Mycological World
Where are fungi in my life?
Your bread, the green fuzz on the bread, the beer in the fridge, the orange-pink crud on the shower curtain, the itch between your toes, the mushrooms on the pizza -- these are all fungi.
Other fungal influences on humans led to the Witch Trials in Salem Massachusetts, Irish immigration to the US in the 1860's, and the savings of millions of human lives through the use of antibiotics.
What exactly are fungi?
Fungi are heterotrophic (they eat other things for food) but are not animals. They typically do not move but are not plants. Fungi can exist as microscopic spores, or may be some of the largest organisms on earth, as with the mycelium or underground portion of an Armillaria
mushroom in Michigan that was estimated to weigh 100 tons.
Most fungi are placed into Kingdom Fungi, and are more closely related to animals than to the plants. A few organisms known loosely as fungi (and also studied by mycologists) are better classified as Protists (the slime molds and Oomycete water molds).
Where else do fungi live?
Fungal threads known as hyphae permeate rock, soil, crops, plant roots, algal cells, and human food stuffs. Fungi live in association with plant roots from nearly every plant group as mycorrhizae, which increase the nutrient uptake capabilities of the plants. Fungi form symbiotic associations with green algae and cyanobacteria to form nearly 15,000 different species of lichens.
Are fungi important for ecosystems?
If it weren't for fungi, the forest floors of temparate regions would be meters deep with non-decayed wood. Fungi are the major recyclers of carbon in many forest ecosystems. Lichen associations between fungi and cyanobacteria, are important for nitrogen fixation in temparate forests. Fungi living inside plant stems as endophytes, produce chemicals that deter herbivores, providing a selective advantage for the plant that contain them. Devastating fungal disesases such as Chestnut Blight and Dutch Elm Disease have wiped out the dominant trees in entire forests.
Are any human diseases caused by fungi?
Yeast infections (Candida species) can range from annoying to life-threatening. Wisconsin has had a large number of infections from Blastomycosis, a fungus that lives in damp soil, and seems to infect dogs in particular. Histoplasmosis can cause debilitating lung infections, and Pneumocystis is a virulent fungus that attacks people with whose immune systems have been compromised by the HIV virus or anti-rejection drugs. Fungi thrive in poorly ventilated structures, and may be responsible for many cases of asthma or sick-building syndrome. Fortunately, a healthy human immune system is very good at combating fungal infections.
Are there any questions left to answer about fungi?
How many fungal species exist?
Unknown. At least 180,000 species that have been identified, but this is probably just the thawed surface of the tip of the iceberg. There may be as many as four million species of fungi that are unknown. Then again, researchers are not always certain what a fungal species is, that is, where to draw the line between different morphological forms or biochemical types. Really, there is more than a little discussion about what constitutes a fungal individual.
Are fungi good for genetic studies? Many fungi are easy to culture, and have biochemical similarities to animals. The first genome sequenced from a eukaryote was that of Saccharomyces cerevisiae, a yeast in the Ascomycota. All the genes known from this fungus are now available on a commercially available genomic array or 'gene chip' allowing researchers to determine exactly which proteins are produced as fungi go through their life cycles, or as they encounter various environmental factors.
What about medicines? The first successful antibiotic Penicillin was derived from a fungus, and undescribed fungi have great potential for providing new antibiotics, immune suppresants, or other metabolites such as alkaloids or statins.
What makes a fungus a fungus? Fungi are very different from either plants or animals. They live in extreme environments from sandstone layers in Antarctica to the driest deserts. Their life cycles often involve prolonged haploid (N) or dikaryotic (N+N) states, and their mating systems range from self-fertile to having hundreds of genders or mating types. They often live in intimate association with algae, plants, or animals, which leads to interesting questions about coevolution and symbiosis.