Memnoniella
Characteristics: Allergenicity has not been studied. No information is available regarding pathogenic effects. It is a toxigenic agent.
Description: It is often found in plant litter, soil, and many types of plants and trees with a dark grey or black coloration. It is disseminated as a dry spore by the wind. It is not considered an allergen. It is not considered a pathogen. As a toxigenic agent, it produces trichthecenes (trichodermol and trichodermin) and griseofulvins. Trichothecene toxicity is due to the ability to bind ribosomal protein. Griseofulvin has been made commercially available as an anti-dermatophyte drug.
Microascus
Characteristics: No information is available regarding health effects or toxicity. Allergenicity has not been studied.
Description: Microascus species are common but comprise a small proportion of the fungal biota. This genus is most closely related to other perithecial forming ascomycetes such as Melanospora. Some species of Microascus have been isolated from clinical sources such as cases of onychomycosis, cutaneous lesions, and mycetomas. Microascus manginii was reported to be the cause of a disseminated infection in a leukemic patient in 1987. No information is available regarding other inhalation health effects or toxicity. Allergenicity has not been studied. May be identified on surfaces by tape lifts, and tease mounts from bulk samples. If Microascus spores are isolated on culturable (Andersen) sampling, the Scopulariopsis anamorph is likely to be the identifiable result, at least with primary growth within one week. May be identified on spore trap samples if the presence of this genus has already been demonstrated (for example, on tape lifts). (Spores have somewhat distinctive morphology but may be confused with other genera.) Recorded isolations are from sunflower seeds, soybeans, sand, soil, chicken litter, and waste compost.
Microstroma
Characteristics: No information is available regarding health effects or toxicity. Allergenicity has not been studied.
Description: Microstroma species comprise a very small proportion of the fungal biota. No information is available regarding health effects or toxicity. Allergenicity has not been studied. May be identified on surfaces by tape lifts, tease mounts from bulk samples, and in air by spore trap samples. (While the spores are only somewhat distinctive, this organism at times becomes airborne with underlying sporulating structures intact, so that the entire organism may be seen on spore trap traces.) In culture Microstroma grows as a yeast. This organism is a plant pathogen, and is common on leaves of Juglans and Carya.
Monilia
Characteristics: No information is available regarding health effects, or toxicity. Allergenicity has not been studied. A single case of human infection was reported in 1961.
Description: Monilia and Chrysonilia are closely related. Monilia is common and may be more common in the eastern and southeastern areas of the United States. The genus is heterogeneous and is not a natural grouping. Commonly grows on sterilized soil in the greenhouse as well as bread (called red bread mold). It has a very rapid growth rate and can be a formidable problem as a contaminant in the laboratory. A single case of human infection was reported in 1961, which was an endophthalmitis following cataract extraction. No information is available regarding other health effects, or toxicity. Allergenicity has not been well studied. May be identified on surfaces by tape lifts, tease mounts from bulk samples, and in air by culturable (Andersen) and spore trap samples. (Spores are a form of arthrospore but are large, variable in size, and distinctive.) Natural habitat is said to be soil, according to some (but not all) references. Monilia sitophilia is not referred to as Chrysonilia sitophilia.
Mortierella
Characteristics: There are no reports of any health effects in humans, although some species cause abortions and pulmonary infections in cattle. No information is available regarding toxicity. Allergenicity has not been studied.
Description: Mortierella species are soil organisms, common, and are related to other zygomycetes such as Mucor. There are no reports of any health effects in humans, although some species cause abortions and pulmonary infections in cattle. No information is available regarding toxicity. Allergenicity has not been studied. May be identified on surfaces by tape lifts, tease mounts from bulk samples, and in air by culturable (Andersen) samples. (Spores do not have distinctive morphology and would be categorized as “other colorless” on spore trap samples.) While most recorded isolations are from soil, other sources include sugar cane, damaged grasses, and vegetable seeds. Our laboratory sees this organism occasionally in quantitative dust samples.
Mucor
Characteristics: Considered a type I and type III allergen. Rarely pathogenic. Not considered toxigenic.
Description: It is often found in organic matter, dung, and soil. It is disseminated as a wet spore by rain splash or as a dry spore by the wind. For indoor growth this fungus is commonly found on leftover food, soft fruits, and juices. As an allergen, it has been known to cause type I symptoms like hay fever and asthma as well as type III symptoms like hypersensitivity pneumonitis. As a pathogen, it has been rarely known to cause infections in severely debilitated patients. As a toxigenic agent, old cultures have been found to produce a substance which inhibits further growth and promotes autolysis of the culture. Mucor produces proteolytic enzymes used in cheese production.
Mycotypha
Characteristics: No information is available regarding health effects, or toxicity. Allergenicity has not been studied.
Description: Mycotypha species comprise a very small proportion of the fungal biota. This genus is most closely related to other one spored mitosporangial zygomycetes such as Choanephora and Cunninghamella. No information is available regarding health effects, or toxicity. Allergenicity has not been studied. Rarely found but may be identified on surfaces by tape lifts, tease mounts from bulk samples, and in air by culturable (Andersen) sampling. (Spores do not have distinctive morphology and would be categorized as “other colorless” on spore trap samples.) Natural habitat is soil.
Myrothecium
Characteristics: Allergenicity has not been studied. No reports as a human pathogen. Considered toxigenic.
Description: It is often found on grasses, plants, soil, and decaying fruiting bodies of russula mushrooms with a grey green coloration. It is disseminated as a wet spore by insects and water splash or as a dry spore through the wind. It is not considered an allergen. It is not considered a human pathogen. As a toxigenic agent, it produces trichothecenes (verrucarins and roridins).
Myxomycetes
Characteristics: Considered a type I allergen. Not considered a human pathogen. Not considered a toxigenic agent.
Description: It is often found in decaying logs, stumps, and dead leaves particularly in forested regions. It is disseminated as a dry spore by the wind. As an allergen, it has been known to cause type I allergen symptoms including hay fever and asthma. It is not considered a human pathogen. It is not considered a toxigenic agent.
Myxotrichum
Characteristics: Heath effects are very rare with only one report of onychomycosis in 1976. No information is available regarding toxicity. Allergenicity has not been studied.
Description: Myxotrichum species comprise a small proportion of the fungal biota. This genus is most closely related to other gymnothecial forming ascomycetes such as Gymnoascus and Ctenomyces. Heath effects are very rare with only one report of onychomycosis in 1976. No information is available regarding toxicity. Allergenicity has not been studied. May be identified on surfaces by tape lifts, and tease mounts from bulk samples. If Myxotrichum spores are isolated on culturable (Andersen) sampling, the Geomyces, Malbranchea, or Oidiodendron anamorph is likely to be the identifiable result, at least with primary growth within one week. (Spores do not have distinctive morphology and would be categorized as “other colorless” on spore trap samples.) This organism is keratinophilic and cellulolytic. Natural habitat is soil. Isolated regularly from paper substrates, damp drywall, decomposing carpets.
