Sierra College Department of Biological Sciences

Discover the Biological Sciences

The introductory information for this site has been contributed as a joint assignment by students in Bio. Sci. 10.

Mycology (Kingdom Fungi)

By: Synthia Silveira

1) Biological field or sub-topic chosen:

Mycology, as define by the Merriam-Webster Dictionary is; a branch of biology dealing with fungi.

2) Define field or sub-topic:
Mycology is the study of the field of Fungi, a classification that is intermediary between plants and animals. Fungi are eukaryotic organisms, originally classified as plants, containing chitin in the cell membrane rather than chlorophyll. Eukaryotic organisms are organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. Chitin is a protective, semitransparent substance, primarily a nitrogen-containing polysaccharide that forms the principal component of arthropod exoskeletons and the cell walls of certain fungi.

3) Describe in more detail the breath and depth of what could be studied or learned within this topic:
There are several classes of fungi. These include the formal groups; chydridiomycota, ascomycota, basidiomycota, and zygomycota. Also included are the two “informal” groups, deutermycota and lichens. Deutermycota and lichens are not classified since scientists do not know where they should be classified. Classes of fungi are based mainly on the type of sexual spore that is produced. The sexual spores are produced by meiosis and are often contained within a structure. Fungi grow as saprophytes and decompose dead organic matter. There are between 100,000 to 200,000 species depending on how they are classified. Mycology study groups include, beer wine, cheese, bread, and mushrooms. It also studies biodegradation or ecological waste management, environmental toxins, and disease.

4) Focusing on one major concept, principle, or group of organisms (as appropriate within the topic), describe its importance, relationships, functional aspects, or otherwise explain it in more depth as seems important to you and (potentially) the others in class:

By studying mycology we are able to identify environmental toxins and diseases invading the environment. The website for the Department of Health and Human Services Centers for Disease Control and Prevention states, “Mycotic infections pose an increasing threat to public health. Opportunistic infections, such as aspergillosis, candidiasis, and cryptococcosis, have emerged as major problems in cancer patients, transplant recipients, and other immuno-compromised individuals, including those with AIDS. Classical infections, such as histoplasmosis and coccidioidomycosis, have appeared in new forms in these patients. There has also been an upsurge in the number of "harmless" environmental fungi - organisms that live in the soil, on plants, in compost heaps, or on rotting food - that have been implicated as causes of serious illness or death in immuno-compromised individuals.”

Mycoses, or fungal infections, are classified depending on the degree to which they invade the tissue and how they enter the host.

Superficial Mycoses infection is localized to the skin, the hair, and the nails (e.g. ringworm, tinea, yeasts, etc). It is identified as an infection of the skin by a dermatophyte. Candidiasis, also known as thrush, is yeast in humans.

Subcutaneous Mycoses are infections confined to the dermis, subcutaneous tissue or neighboring structures. Infection may arise following the wounding of the skin and the introduction of a vegetable matter. An example is sporotrichosis caused by Sporothrix schenckii. The fungus is dimorphic, or a mould that can convert to a yeast form at 37°C on rich laboratory media or in infection. Sporotrichosis, once common in Europe, is rare now.

Systemic Mycoses are invasive infections of the internal organs. The organism gains entry by the lungs, gastrointestinal tract or through intravenous lines mainly affecting people whose immune system is compromised.

Primary Pathogenic Fungi occurs in previously healthy persons. By following the respiratory route the lungs are the primary site of infection. Once infected, the flow can continue through the liver, heart and central nervous system. Pulmonary infection often resembles symptoms seen in tuberculosis.

Opportunistic Fungi include aspergillosis, systemic candidosis and cryptococcosis. These organisms infect the lungs, inner ear, sinuses and the eyes.

Candidosis can proliferate rapidly throughout the body and is often found in severely immuno-compromised patients (e.g. someone receiving chemotherapy).

Cryptococcosis is a systemic infection caused by the yeast Cryptococcus neoformans. The most common occurrence is a chronic form of meningitis resulting from the inhalation of the organism.

Exposure to fungal spores in the air can result in respiratory allergies. Certain fungi, such as mushrooms, can produce poisonous toxins that may prove fatal if ingested (e.g. Amanita phalloides or death cap). Other fungi may affect the central nervous system inducing hallucinogenic responses similar to LSD. Many moulds produce lesser metabolites (mycotoxins) that are highly toxic. Historical documentation reveals several large scale occurrences of poisoning due to populations ingesting bread with infected rye (ergotism or the poisoning by the ingestion of alkaloids produced by a type of fungus).

Pneumocystis, an infection of the lung caused by Pneumocystis carinii (a group of ustomycetous red yeast fungi) is a common cause of fatal pneumonia in AIDS patients.

There is a rise in the medical study of mycology due to several factors such as the increase in mycotis diseases and the increase in immunosuppressive diseases. Given that there are now better laboratory diagnostic tools and trained personnel, there is an awareness of the relationships between the study of mycology and effects on humans.

5) In studying and discovering more about this topic, what was the most interesting aspect, fact or some other piece of information that you have learned.

About 300 species are presently known to be pathogenic for man. However, mycotic diseases are not contagious but depend on inoculum size (amount of a virus, toxin or immune serum introduced into the body) and resistance of the host. Uninhibited travel contributes to the increase in new diseases and the necessity to refine research in various fields such as mycology to prevent wide spread contamination and, once spread, stop the proliferation of contamination.

6) References – provide references used and at least two Web sites with additional information on this topic (or sub-topic) for anyone that would like to learn more:

Identification of Fungi, Richland College;

Department of Health and Human Services Centers for Disease Control and Prevention;

EmLab P&K Microbiological Laboratory;

Neurological syndromes associated with the ingestion of plants and fungi with a toxic component (II).
Hallucinogenic fungi and plants, mycotoxins and medicinal herbs;

(return to the "Discover the Biological Sciences" main index page)

W3C Logo: Valid HTML 4.01 Transitional W3C Logo: Valid CSS