Mycology and Fungi Roles in Life

Study Notes

Mycology is the study of fungi, commonly called yeasts and molds.
It includes studying their genetic and biochemical properties.
It also involves their taxonomy and their roles in human life including uses as tinder, medicinals (e.g., penicillin), food (e.g., beer, wine, cheese), and entheogens (psychoactive substances).
Fungi are also studied for their dangers such as poisoning or infection.

Many fungi produce toxins, antibiotics, and other secondary metabolites (products of metabolism).
Some fungi are fundamental for life on Earth, acting as symbionts, forming mycorrhizae, insect symbionts, and lichens.
Fungi can break down complex organic biomolecules (e.g., lignin, xenobiotics, petroleum, polycyclic aromatic hydrocarbons).
Fungi play a critical role in the global carbon cycle through decomposition.

Some fungi are traditionally recognized as oomycetes and myxomycetes (slime molds).
Some fungi are economically and socially important because they cause diseases in animals (such as histoplasmosis) and plants (e.g., elm disease and Rice blast).
Many fungi cause disease in humans or other organisms.
The study of pathogenic fungi is called medical mycology.

Actinomycetes are a large group of prokaryotic organisms that are similar to fungi in morphology but are smaller.
They are a collective name for eight families of bacteria.
These bacteria grow as frequently branched or long filaments of cells called hyphae (branched mycelia; unbranched hyphae).
Actinomycetes are definitively bacteria.

The main body of most fungi is composed of branching, colorless threads called hyphae.
Each fungus has many hyphae that intertwine to form a tangled web called the mycelium.
Fruiting bodies, such as mushrooms, are collections of hyphae.
Fruiting bodies vary in size from small and insignificant to large and noticeable.
They are usually produced on the surface of the food source to spread spores by wind, water, or animals.

Candida species are important human pathogens.
They are known to cause opportunistic infections in immunocompromised hosts, such as transplant patients, AIDS sufferers, and cancer patients.
Candida infections can be difficult to treat and are often serious, with 30–40% of systemic infections proving fatal.

Aspergillus spores are commonly found everywhere, exposing people.
The most common pathogenic species are Aspergillus fumigatus and Aspergillus flavus.
Aspergillus flavus produces aflatoxin, a toxin and carcinogen that can contaminate food.
Aspergillus species can cause allergic disease.
Some species cause disease in grain crops (especially maize) and produce mycotoxins (e.g., aflatoxin).
Aspergillosis is a group of diseases caused by Aspergillus.
Aspergillosis symptoms include fever, cough, chest pain, and/or breathlessness; it usually only affects patients with a weakened immune system or other lung conditions.

Cryptococcus neoformans can cause severe meningitis and meningoencephalitis in HIV-infected patients.
Most Cryptococcus species live in the soil and don't cause disease in humans.

Histoplasma capsulatum can cause histoplasmosis (primarily affects the lungs) in humans.
The fungus is prevalent in the Americas, India, and Southeast Asia.
Infection usually comes from inhaling contaminated air.