The singular term "fungus" generically refers to all members of the Kingdom Fungi, plant-like organisms that lack chlorophyll. Since fungi don't use light to make food, they can live in damp and dark places and they must absorb food from existing sources.
Each of the terms fungi, mold or yeast are sometimes used interchangeably in the literature.
The Science of Fungus
Fungi are extensively studied because of their usefulness to humans but also their health-damaging effects, in a science called mycology. In particular, there are:
- Agricultural mycologists who study the industrial uses of fungi
- Medical mycologists who study drugs to cure fungal infections
When one delves deeper into the topic of fungi, the underlying terminology can be very technical and complex. Fungi can basically be divided into two broad groups of organisms with different appearance and cell structure:
- Yeasts are small, distinct round forms and single-celled
- Molds are tentacle-like, fuzzy and multi-celled
Yeasts
There are about 1,500 known species of yeasts and they dominate fungal diversity in the oceans.
Yeasts (Fig. 1) are solitary single-celled rounded forms and are available commercially as small round granules. They reproduce by making more rounded forms through such mechanisms as budding or fission, in which they actively divide, grow, and metabolize into this form of the fungus. The colonies are typically moist and resemble mucus.
Yeasts have been used in baking and fermenting alcoholic beverages for thousands of years. They have also been used as nutritional supplements and are popular with vegans. Yeast extracts are used as additives and flavor enhancement.
Yeast can cause food spoilage. The growth of yeast within food products is often seen on their surface, as in cheeses or meats, or by the fermentation of sugars in beverages, such as juices, syrups and jams. Candida albicans is an opportunistic species of yeast that can cause infections in humans with compromised immunity systems.
Molds
Molds (Fig. 2) are multi-celled, interwoven filaments known as hyphae, which grow by elongation of their tips. The entire mass of hyphae is called a mycelium. Some are very large and have been measured to be in the order of kilometers.
- Mushrooms are a special case of mold, only existing for part of the fungus life cycle. The familiar button appearance or “fruiting” body is designed to make and release tiny spores so that the fungus can reproduce. Some spores can remain airborne indefinitely and many are able to survive extremes of temperature and pressure.
- Other molds do not have a body but the hyphae become exposed to the surface so that they can release spores to the environment.
Cultured molds are useful for their role in biodegradation or in the production of various foods, including cheese, sausages and soy sauce; beverages; antibiotics and enzymes. Alexander Fleming's famous discovery of the antibiotic penicillin involved the mold Penicillium chrysogenum.
When mold spores are present in large quantities, they can pose a health hazard to humans, potentially causing allergic reactions and respiratory problems. Some molds produce mycotoxins, which pose serious health risks to humans and animals. Exposure to high levels of mycotoxins can lead to neurological disorders and other problems (e.g. potential cancer connection) and in some cases, death.
Removal of Fungus and Molds
As fungus and molds can cause allergies and fungal infection through breathing the air they occupy and inside and on the surface of foods, it is desirable to remove them from the home and to be vigilant of the foods we eat. Mold remediation in damp areas of the home are important. Cooking foods kills mold but when storing in the refrigerator as cold food, colonies can multiply again. Fungus can grow on the body, such as under nails including under the toe nails. The simple application of sodium bicarbonate (baking soda) has been useful in the treatment fungal skin conditions.
Summary
Fungi are an important species and receive a kingdom classification of their own. Fungi are ubiquitous in nature and are involved in every part of our lives. Some fungi are beneficial to life on the planet, whilst others are harmful to human health.
