Mycology PDF

# Mycology Mycology involves the study of: * **Fungi** (commonly called yeasts and molds) * **Their genetic and biochemical properties** * **Their taxonomy and use to humans as a source for:** * Tinder * Medicinals (e.g., penicillin) * Food (e.g., beer, wine, cheese, edible mushrooms)...

# Mycology Mycology involves the study of: * **Fungi** (commonly called yeasts and molds) * **Their genetic and biochemical properties** * **Their taxonomy and use to humans as a source for:** * Tinder * Medicinals (e.g., penicillin) * Food (e.g., beer, wine, cheese, edible mushrooms) * Entheogens (a psychoactive substance used in a religious, shamanic, or spiritual context) * **Their dangers,** such as poisoning or infection **Many fungi** produce toxins, antibiotics and other secondary metabolites (products of metabolism that are not absolutely required for the survival of the organism. e.g., antibiotics and pigments) **Fungi** are fundamental for life on earth in their roles as symbionts, e.g. in the form of mychorrhizae, insect symbionts and lichens **Many fungi** are able to break down complex organic biomolecules such as lignin (more durable component of wood), and pollutants such as xenobiotics, petroleum, and polycyclic aromatic hydrocarbons **By decomposing these molecules, fungi play a critical role in the global carbon cycle** **Fungi** and other organisms traditionally recognized as fungi, such as oomycetes and myxomycetes (slime molds) **Economically and socially important** as some cause diseases of animals (such as histoplasmosis) as well as plants (such as Dutch elm disease and Rice blast) **Some fungi** can cause disease in humans or other organisms **Study of pathogenic fungi** is referred to as medical mycology ## Actinomycetes * A large group of prokaryotic organisms that are smaller than, but morphologically similar to, fungi * Collective name for eight different families of bacteria that grow as frequently branched, long or short filaments of cells (hyphae: unbranched; mycelia: branched) * Actinomycetes truly are bacteria ## Structure of Fungi * **Main body of most fungi** is made up of fine branching, usually colourless threads called hyphae * **Each fungus** will have vast numbers of these hyphae, all intertwining to make up a tangled web called the mycelium **Fruiting bodies** (such as mushrooms) are made up of thick collections of hyphae * They vary in size from small and insignificant, to large eye-catching structures * They are usually produced at the surface of the food source, to allow the spores to be shed and carried away by the wind, or by water, or animals # Pathogenic Fungi ## Candida * Candida species are important human pathogens that are best known for causing opportunistic infections in immunocompromised hosts (e.g. transplant patients, AIDS sufferers, cancer patients) * Infections are difficult to treat and can be very serious: 30-40% of systemic infections result in death ## Aspergillus * Aspergillus spores are found nearly everywhere so we are routinely and almost constantly exposed to them * Most common pathogenic species are Aspergillus fumigatus and Aspergillus flavus * Aspergillus flavus produces aflatoxin which is both a toxin and a carcinogen and which can potentially contaminate foods such as nuts * Aspergillus fumigatus and Aspergillus clavatus can cause allergic disease * Some Aspergillus species cause disease on grain crops, especially maize, and synthesize mycotoxins including aflatoxin * Aspergillosis is the group of diseases caused by Aspergillus * Symptoms include fever, cough, chest pain or breathlessness * Usually, only patients with weakened immune systems or with other lung conditions are susceptible ## Cryptococcus * Cryptococcus neoformans can cause a severe form of meningitis and meningo-encephalitis in patients with HIV infection and AIDS * Majority of Cryptococcus species live in the soil and do not cause disease in humans ## Histoplasma * Histoplasma capsulatum can cause histoplasmosis (disease primarily affects the lungs) in humans, dogs and cats * Fungus is most prevalent in the Americas, India and southeastern Asia * Infection is usually due to inhaling contaminated air ## Pneumocystis * Pneumocystis jirovecii (or Pneumocystis carinii) can cause a form of pneumonia in people with weakened immune systems, such as premature children, the elderly, and AIDS patients.