July 5, 2022

Mold is a term that refers to the appearance of some fungi. It is also a common name for a colony of microorganisms that looks similar to it and is visually observed.


In a narrow sense, the word mold is a fungus that does not form fruiting bodies, has the appearance of filamentous fungi, that is, has a body composed of hyphae. Corresponding to this are those of zygomycetes, as well as conidia (also imperfect) of ascomycetes and basidiomycetes. When cultured cleanly, they form circular colonies consisting of fluffy hyphae and form a large amount of spores on the surface. Plant parasites such as rust also fall into this category. However, if hyphae do not appear on the surface of the plant, it is difficult to recognize mold with the naked eye. In addition, among the ascomycetes that produce very small fruiting bodies, there are examples called by the name of mold (Chaetomium, Ascobolaceae, Erysiphaceae, etc.). However, when we see a general colony of microorganisms with such a figure, we often refer to it as mold. In particular, it refers to the intricate mycelium of fungi. Therefore, even a fungus having a large fruiting body, which is commonly called mushroom, is recognized as a mold when only the mycelium, which is the nutrient body thereof, is visually recognized. In addition, even yeast, which is a fungus that does not produce mycelium, may also be recognized as a mold when it forms a dense and powdery colony on the surface. Filamentous fungal organisms that grow in water are also called saprolegnia. Until recently, it was thought to be a fungus, so it is called a mold-like name. Although these organisms have a life-form similar to mold, most of them (oomycetes) are now considered to be non-fungi. In addition, since the word mold was used as the name of small fungi, the name is also used for things that do not form hyphae, such as chytrids and owl molds. In addition to fungi, some protists such as slime molds and Dictyostelium discoideum are named molds. Thus, it is difficult to define mold biologically, but from an applied microbiological point of view, the fungi that form fruiting bodies recognized as mushrooms and those excluding yeast are described below. Will be described in detail in.


Mold consists of filamentous cells called hyphae, which grow by spores. In the living space, it occurs in humid seasons and places such as the rainy season and typhoon season, for example, on the surface of food, clothing, and the walls of bathtubs. In many cases, it causes deterioration and putrefaction of the product, or dislikes the peculiar odor, and is said to have a moldy odor. It may cause food poisoning and allergies in some people. There are many mold removers, but many of them give off a pungent odor and are rather dangerous. On the other hand, some play an important role in making fermented foods and medicines (such as penicillin).

Life history of mold

Mold is a common name for fungi that span multiple classification items, and there are molds with various lifestyles. For example, the common mold Rhizopus stolonifer belongs to the zygomycota, which is one of the fungi. When spores floating in the air come into contact with the surface of moist organic matter such as rotten plants, they germinate and form a network of hyphae. In addition, by secreting enzymes from the surface of hyphae, organic matter is decomposed and nutrients are absorbed. The characteristic of the zygomycota is that it has two breeding patterns.