Some common fungi and their known health effects:

Absidia

Absidia belongs to the class zygomycetes (also known as pin mold) and has about 21 species. They are found in soil, plant debris, foods and known to cause food spoilage. It is also known to occur in indoor environments from the air and surface samples. The fungus grows rapidly, produces woolly to cottony and olive gray colonies within 3-4 days. The sporangiophores are branched and arise in groups of 2-5 at the internodes. Sporangiophores carry pyriform, relatively small (20-120 µm in diameter) sporangia. Absidia corymbifera is the most commonly occurring species, reported as an animal pathogen but may also cause zygomycosis to immunocompromised patients’ invloving pulmonary, rhinocerebral, cutaneous, gastrointestinal, renal or meningeal infections.

Acremonium

Acremonium belongs to the group hyphomycetes and has about 100 species. Four most common species are A. strictum, A. terricola, A. bacillisporum and A. kiliense. They need high moisture content to grow and reproduce and are common on wet environments. They can be found in soil and plant debris. They are also known to occur in indoor specially wet cellulose-based building materials. The fungus produces small, hyaline spores in sticky masses or chains from simple phialidic conidiophores. A few species are known to produce mycotoxin (e.g. citrinin and trichothecene).Acremonium kiliense is a well-known opportunistic pathogen and cause mycosis on humans.

Alternaria

Alternaria belongs to the group hyphomycetes and has about 44 species. Alternaria is a very common outdoor fungus known to cause leaf spot/leaf decay on plants.Alternaria alternatais the most common indoor species. The fungus colonizes indoor substrata such as textiles, carpets, wood, ceiling tiles and drywall paper. Species of Alternaria produce large, multicellular, brown spores, often in chains. The fungus produces several mycotoxins such as altenuic acid, gliotoxin, altertoxin, and tenuazonic acid. It is a common agent for hay fever, asthma, and other allergy-related symptoms. The fungus is not normally pathogenic but opportunistic disease has been reported to immunocompromised patients.

Aphanocladium

Aphanocladium belongs to the group hyphomycetes and has 6 species. The fungus produces white cottony mycelia that contain hyaline spores from phialides borne at right angles of the hyphae. Aphanocladium album is the most common species and has been isolated from soil and plant debris. In indoor environment, the fungus can be found on wet wood. None of the species are known to produce mycotoxin. Health effects on humans and animals are unknown.

Arthrinium

Arthrinium belongs to the group hyphomycetes and has about 20 species. The fungus produces dark, one-celled, distinctively shaped conidia with a pronounced hyaline rim or germ slit. It can be found in soil and decomposing plant material. It is common in outdoor but occasionally it can be found on indoor environment. None of the species of Arthrinium are known to form mycotoxin. There are no infections so far reported due to Arthrinium in humans or animals.

Arthrobotrys

Arthrobotrys belongs to the group hyphomycetes and has about 28 species. It produces large, two-celled, obovate spores that are formed on node-like swellings on more or less simple conidiophore. It can be found in soil and are commonly found as predators of nematodes. Although it is an outdoor fungus, species of Arthrobotrys have also been reported from indoor environment. There are no infections so far reported due to Arthrobotrys in humans or animals.

Ascospores

Ascospores are produced by the fungi belonging to class Ascomycetes. This class has more than 3000 different genera. Many species are common in outdoor and some are known to colonize indoor environment on wet building material. Some of the common ascomycetes that occur in indoor environment are Chaetomium, Eurotium, Myxotrichum, Petriella, and Peziza.

Aspergillus

Aspergillus belongs to the group hyphomycetes and has approximately 180 species. The fungus produces conidiophores with apical vesicle bearing numerous phialides with spores in long, dry chains. Biologically it is one of the most successful of all fungi, shows great physiological adaptability and grows on all types of organic matters. They have very low moisture requirements and some of them are xerophilic (dry tolerant). As a result, they can colonize in substrate where only minimal or intermittent moisture is available and can successfully compete with other fungi for their low moisture requirement. Species of Aspergillus can grow and reproduce very rapidly. They produce large numbers of dry spores within a short period of time that can easily become air-borne and can cause potential human exposure related illness. Several species of Aspergillus are known to produce mycotoxin such as A. flavus (aflatoxin, B1 and B2 cyclopiazonic acid and kojic acid), A. fumigatus (fumitremorgin, fumigillin, fumigatoxin, gliotoxin, fumigaclavines, verruculogen, and ergot alkaloids), A. niger (malformin C and oxalic acid), A. ochratoxin (ochratoxin), A. terreus (patulin), A. ustus (austocystins), A. versicolor (sterigmatocystin, aspercolorin, averufin, cyclopiazonic acid, versicolorin). A few species are known to cause human infections including aspergillosis (invasion of the lungs or respiratory tract) caused by A. fumigatus. Aspergillus niger is known to cause otomycosis or ear infection. Many species of Aspergillus are known as allergens (Type I or atopic allergy) or Type III allergy (hypersensitivity pneumonitis and allergic sinusitis) caused by A. fumigatus.

Aurobasidium

Aurobasidium belongs to the group hyphomycetes and has about 15 different species. Conidiophoress lacking, conidia arising individually, directly from the vegetative hyphae on short denticles, vegetative hyphae hyaline to darkly pigmented, conidia ovoid. The colonies are dark brown in color and tend to be water-soaked or yeast-like appearance. It is a dematiaceous fungus found on plant debris, soil, wood, textiles, fresh water, painted surfaces, and in flower nectar. In indoor, the fungus is commonly found growing on surfaces that are continually damp in bathrooms and kitchens such as shower curtains tile grout and window sills. The fungus may cause allergy, asthma, and hay fever to immunocompromised people. It is an opportunist fungus and may colonize hair, skin, and nails. It is not known to produce any mycoroxin.

Basidiospores

Basidiospores are produced by the fungi belonging to the class Basidiomycetes and have more than 1200 different genera. This group includes wood decay fungi and mushrooms. They occur in all different types of biogeographical zones and are one of the most frequent spores of the outside air samples. Spores are distributed by the wind and large numbers of spores are released during periods of high humidity or rain. Many species are wood decaying fungi and can colonize building materials (wood) and cause extensive damage such as species of Meruliporia, Serpula, Antrodia, Phellinus, and Gloeophyllum. Some of the mushrooms are poisonous and poisoning (toxicosis) is usually attributable to ingestion of mushrooms that produce toxins such as amanitins, monomethyl-hydrazine, muscarine, ibotenic acid, and psilocybin. Inhaling large numbers of basidiospores may cause hay fever, asthma, and allergy to certain people.

Bipolaris/Drechslera group

They belong to the group hyphomycetes and have about 50 different species. They are found in soil, plant debris, wood, and paper. Bipolaris has indeterminate conidiophores which extend sympodially producing a succession of large dark and transversely septate spores. Spores are basically fusoid in shape and germinate only from the end. Large spores can be deposited in the upper respiratory tract and may cause allergic fungal sinusitis, asthma, and hay fever. It is also known to produce mycotoxin (sterigmatocystin) that can damage liver in kidney on animals. The fungus may also cause keratitis and osteomyelitis on humans.

Botrytis

Botrytis (also known as grey mold) belongs to the group hyphomycetes and has about 30 different species. It is a plant parasite as well as saprophytes on both agricultural and forest trees. It produces stout, dark, branching conidiophores that bear clusters of paler conidia (grey in mass) on denticles from apical ampullae. It is a common outdoor fungus and can be detected in spore trap samples. The fungus is often found growing on indoor plants. Although no mycotoxin has been reported from this fungus, it may cause hay fever, asthma and keratomycosis.

Ceratocystis/Ophiostoma

They belong to the class ascomycetes, commonly known as "lumber mold" and usually found on freshly cut lumber. They do not cause decay of the wood but reduce the aesthetic value. Some of the species are important plant parasites causing extensive damage (Dutch elm disease). Ascospores and spores of Leptographium and Sporothrix mold states are produced in sticky masses and are not readily airborne unless disturbed.Ceratocystis / Ophiostoma are common in indoor environment and is usually is not associated with building moisture problem. They may be present on the wood since the construction began. Hyphae of Ceratocystis / Ophiostoma can become air-borne and can be seen in indoor air sample. Pathogenicity of Ceratocystis / Ophiostoma is unknown and no mycotoxins have been reported from this group.

Chaetomium

Chaetomium belong to the class ascomycetes and has more than 80 species. The fungus produces perithecia that contain asci. Each ascus produces 8 ascospores that are single-celled, light olive-brown to dark brown.Chaetomium is often found growing in soil, seeds, cellulose substrates, dung, straw, woody material, damp sheetrock, drywall, gypsum board, and on sub floor. It is known to produce mycotoxin (chaetomin, sterigmatocystin and chaetoglobosins). The fungus has been reported to be allergenic and may cause hay fever or asthma. In rare cases, some species can cause onychomycosis or nail infection.

Cladosporium

Cladosporium belongs to the group hyphomycetes and have about 50 different species. It produces darkly pigmented brown spores in branching chains. This genus can be frequently identified by the conidia alone, which have well marked, dark attachment scars and show considerable variation in size and septation. It is one of the most abundant molds in the outdoor environment and can be found growing in soil, leaf surfaces, and decomposing plant material. Cladosporium is a dominant fungus in outdoor air as well as indoor environment. In indoor, the fungus can be found growing on textiles, sheetrock, subfloor, oriented stand board, plywood, wood, painted walls, moist window sills, tile grout and often in bathrooms where relative humidity is regularly above 50%. Since Cladosporium is ubiquitous in nature, it is not regarded as one of the most important indoor species, unless present in extremely high levels. It is a common agent of allergic reactions and some people may experience hay fever and asthma. Some species may produce mycotoxin (cladosporin and emodin) but none of them are known to be highly toxic.

Coliforms

Coliforms are bacteria that are always present in the digestive tracts of animals, including humans, and are found in their wastes (feces). They are used as an index of sanitation. Coliforms are aerobic or facultative anaerobic, Gram negative, non-spore-forming, rod-shaped bacteria that ferment lactose within 48 hours at 35 C. Coliforms include members of at least three genera: Escherichia, Klebsiella, and Enterobacter. Since coliforms are common inhabitants of the intestinal tract, their presence in food may indicate fecal contamination. Therefore, coliforms are known as “indicator” microorganisms.

The most basic test for bacterial contamination of a water supply is the test for total coliform bacteria. Total coliform counts give a general indication of the sanitary condition of a water supply. Total coliforms include bacteria that are found in the soil, in water that has been influenced by surface water, and in human or animal waste.

Fecal coliforms are the group of the total coliforms that are considered to be present specifically in the gut and feces of warm blooded animals. Because the origins of fecal coliforms are more specific than the origins of the more general total coliform group of bacteria, fecal coliforms are considered a more accurate indication of animal or human waste than the total coliforms.

Escherichia coli (E. coli) is the major species in the fecal coliform group. Of the five general groups of bacteria that comprise the total coliforms, only E. coli is generally not found growing and reproducing in the environment. Consequently, E. coli is considered to be the species of coliform bacteria that is the best indicator of fecal pollution and the possible presence of pathogens.

Most coliform bacteria do not cause disease. Testing for coliform bacteria can be a reasonable indication of whether other pathogenic bacteria are present. However, some rare strains of E. coli, particularly the strain 0157:H7, can cause serious illness.

Cryptococcus

Cryptococcus belongs to the group hyphomycetes and have about 37 different species. Cryptococcus neoformans is the only species that is pathogenic to humans and animals. It is a nonpigmented, nonfilamentous yeast characterized by the ability to form a capsule and starch. The fungus can be isolated from soil contaminated with pigeon droppings, plant litter, or goats with pulmonary disease. It grows well at 250C (filamentous form) and 370C (yeast form). The perfect (sexual) form or telemorph is called Filobasidiella neoformans (basidiomycetes and forms basidiospores), but the imperfect (asexual) form or anamorph is called C. neoformans. Once inside the lungs, the yeast cells become rehydrated and acquire the characteristic polysaccharide capsule. In the case of basidiospores, they would convert to encapsulated blastoconidia. The fungus causes meningitis and meningo-encephalitis in person with HIV infections and AIDS or immunocompromized people.

Curvularia

Curvularia belongs to the group hyphomycetes and have about 30 different species. It is common in outdoor environment and can be found in soil, leaves, and plant debris. In indoor, Curvularia species are found on a wide variety of building materials containing cellulose. The fungus produces dark, curved spores with paler end cells. Production of mycotoxins by this fungus has not been reported at this time. It is considered to be common allergen. Some people may experience hay fever, asthma and allergic fungal sinusitis. It may also cause corneal infections, onychomycosis or nail infection, pneumonia, and mycetoma. Most cases infections occur to immunocompromised people.

Escherichia coli (E. coli)

Escherichia coli (E. coli) belongs to the family Enterobacteriaceae. It is a Gram negative flagellated rod-shaped bacterium. It is a facultative anaerobe (can grow in both presence and absence of oxygen), oxidase negative, indole positive, and does not utilize citrates. It ferments glucose and other carbohydrates, producing acid and gas.

E. coli are members of a large group of bacteria that inhabit the intestinal tract of humans and other warm blooded animals (mammals, birds). Newborns have a sterile alimentary tract which within two days becomes colonized with E. coli. More than 700 serotypes of E. coli have been identified. The different E. coli serotypes are distinguished by their “O” and “H” antigens on their bodies and flagella, respectively. The E. coli serotypes that are responsible for the numerous reports of contaminated water, foods and beverages are those that produce Shiga toxin (Stx), so called because the toxin is virtually identical to that produced by another bacteria known as Shigella dysenteria type 1 (that also causes bloody diarrhea and hemolytic uremic syndrome). The best known and most notorious Stx-producing E. coli is E. coli O157:H7.

Stx-producing E. coli organisms have several characteristics that make them so dangerous. They are hardy organisms that can survive several weeks on surfaces such as counter tops, and up to a year in some materials like compost. They have a very low infectious dose meaning that only a relatively small number of bacteria, less than 50 cells, are needed to cause infection. E. coli can be transmitted from contaminated water, animals, and humans.

E. coli infection occurs when a person ingests Shiga toxin (Stx)-producing E. coli (e.g., E. coli O157:H7) after exposure to contaminated water, food, beverages, animals, or other persons. After ingestion, E. coli bacteria rapidly multiply in the large intestine and bind tightly to cells in the intestinal lining. This snug attachment facilitates absorption of the toxin into the small capillaries within the bowel wall where it attaches to globotriaosylceramide (Gb3) receptors.

Inflammation caused by the toxins cause of hemorrhagic colitis, the first symptom of E. coli infection, which is characterized by the sudden onset of abdominal pain and severe cramps, followed within 24 hours by diarrhea. Hemorrhagic colitis typically occurs within 2 to 5 days of ingestion of E. coli, but the incubation period, or time between the ingestion of E. coli bacteria and the onset of illness, may be as broad as 1 to 10 days.

As the infection progresses, diarrhea becomes watery and then may become grossly bloody, that is, bloody to the naked eye. E. coli symptoms also may include vomiting and fever, although fever is an uncommon symptom.

On rare occasions, E. coli infection can cause bowel necrosis (tissue death) and perforation without progressing to hemolytic uremic syndrome (HUS) a complication of E. coli infection that is now recognized as the most common cause of acute kidney failure in infants and young children.

During HUS, the majority of the toxin gains access to the systemic circulation where it becomes attached to weak receptors on white blood cells (WBC) thus allowing the toxin to “ride piggyback” to the kidneys where it is transferred to numerous strong Gb3 receptors that grasp and hold on to the toxin.

Organ injury is primarily a function of Gb3 receptor location and density. These receptors are probably always in the gut wall and kidneys, but heterogeneously distributed in the other major body organs. This may be the reason that some patients develop injury in other vital organs (e.g., brain, etc). Once Stx attaches to receptors, it moves into the cells’ cytoplasm where it shuts down the cells’ protein machinery resulting in cellular injury or death, and subsequent damage to vital organs such as the kidney, pancreas, and brain.

Engyodontium

Engyodontium belongs to the group hyphomycetes and have about 6 different species. This fungus was formerly included in Beauveria, but now recognized as a distinct genus. In outdoor it is common in soil and plant debris. In indoor, it can found on paper, textile, jute, and painted walls. The most common species is E. album. It forms a cottony, white colony producing numerous dry, tiny conidia. Production of mycotoxins by this fungus has not been reported at this time. It is an opportunist fungus and cause brain abscess, keratitis, native valve endocarditis to immunocompormised people.

Epicoccum

Epicoccum belongs to the group hyphomycetes and has 2 species. It can be found in soil, plant litter, decaying plants, and damaged plant tissue. In indoor, Epicoccum can be found in paper, textiles, and insects. It produces yellowish or orange hyphae and clusters of dark, globose to subglobose, muriform spores. The fungus is known to produce antibiotics (epicorazine A and B, indole-3-acetonitrile, and flavipin). Immunocompromised people may experience hay fever and asthma if exposed to this fungus. It has not been linked to any human or animal infection.

Eurotium

Eurotium is a genus of ascomycetes (sexual state of Aspergillus) characterized by whitish to bright yellow spherical fruiting bodies (cleistothecia) containing spherical asci which contain eight colourless ascospores. Species of Eurotium grow best in dry situations and are usually cultivated on media high in sucrose or glycerine. In outdoor, it can be found in soil and plant debris. In indoor, the fungus can be found in stored grains, textiles, leather, materials coated with resins and lacquers, such as furniture, and rodent dwellings. It forms Aspergillus, notably A. glaucus in anamorph (asexual stage). Eurotium is common and is most closely related to Emericella, another genus with Aspergillus anamorphs. Eurotium is likely to be present along with related Aspergilli if growth has been long term and the nutrients of the substrate are conducive for the conversion to sexual phase. Health effects, allergenicity, and toxicity of Eurotium are closely related to the Aspergillus anamorph (please see under Aspergillus).

Fusarium

Fusarium belongs to the group hyphomycetes and has about 70 different species. It can be found growing on soil and plants. It can be found in outdoor as a saprophyte and parasite on agricultural, horticultural, and forest trees. In indoor, it grows on building materials, cooling units of air conditioning systems, soil, carpet, drywall papers, mattress dust, textiles, wood, seeds and fruits. It needs wet condition to grow and multiply. It forms boat-shaped macroconidia that are hyaline, containing 2 to several septa, slimy, with well marked foot cell at the attachment end of the spore. Microconidia are smaller, ovoid to short cylindric, gathering in short chains or more commonly in spore balls. It can produce several mycotoxins such as trichothecenes (Type B), T-2 toxin, zearalenone (F-2 toxin), vomitoxin, deoxyniyalenol, and fumonisin. Fusarium species are known to cause Type I allergies (hay fever, asthma). It can also cause keratitis, onychomycosis or nail infection, and mycetoma. Zearalenone not not acutely toxic, it has been patented as a growth stimulant in animals and has a potential application as an oral contraceptive, in addition to being recognized as an anabolic steroid (<1ppm). Fusarium graminearum is used for the production of quorn (a mycoprotein) for human consumption. The product contains many fibers and is used in pies in the United Kingdom and some other countries.

Geotrichum

Geotrichum belongs to the group hyphomycetes and has about 12 different species. It can be found worldwide in soil, water, air, and sewage, as well as in plants, cereals, and dairy products. It is also found in normal human flora and is isolated from sputum and feces. It is a yeast-like fungus and reproduces by arthrospores (vegetative hyphae fragment into unicellular units). Production of mycotoxins by this fungus has not been reported at this time. Being a colonizer of the intestinal tract, the fungus may cause opportunistic infections in immunocompromised host and these infections are referred to as geotrichosis. Bronchial, oral, vaginal, cutaneous and alimentary infections have also been reported by this fungus.

Gonatobotryum

Gonatobotryum belongs to the group hyphomycetes. Gonatobotryum fuscum is the most common species and it grows as a mycoparasite of the ascomytcete fungi Ophiostoma and Ceratocystis. Other natural habitats of this fungus include soil, and rotten wood, and parasitic on certain other plants. Most homes built with lumber have areas of growth of both Ophiostoma / Ceratocystis and Gonatobotryum on wood framing inside walls. Usually all lumberyards have some percentage of boards with areas of this black mold growth. The fungus can be identified by its broad brown hyphae, swollen, nodose conidiophores, and smooth, brown, ellipsoidal conidia. Production of mycotoxins by this fungus has not been reported at this time. Also no information regarding health effects, toxicity or allergenicity is available.

Graphium

Graphium belongs to the group hyphomycetes and has about 20 different species. It can be found in soil, plant debris, woody substrate, manure, polluted water. The sporulating structures of Graphium form synnema, which are a gathering of conidiophores into a sort of flower bouquet. Graphium spp. are recognized by their distinctive, erect, black synnemata, each bearing a single, terminal, ball of one-celled, hyaline conidia produced from annellides. There are no reports of illness due to the Graphium.

Histoplasma

Histoplasma belongs to the group hyphomycetes and has one species H. capsulatum and has two varities, H. capsulatum var. capsulatum and var. H. capsulatum, var. duboisii. The telemorph or sexual state of this fungus is an ascomycotous fungus, Ajellomyces capsulatus. Histoplasma can be found in soil contaminated with bird dropping or excrements of bats. It is a dimorphic fungus, grows as granular to cottony at 250C (the color is white initially and usually becomes buff brown with age) and yeast-like colony at 370C . The fungus is known to cause histoplasmosis. The range of the disease includes an acute benign pulmonary infection to a chronic pulmonary or fatal disseminated disease. Lungs are primarily infected site when conidia are inhaled. In cases of dissemination of Histoplasma capsulatum var. capsulatum infection, reticuloendothelial system is most frequently involved. Histoplasma capsulatum may also rarely involve the thyroid glands and may be isolated in fungemia. Unlike var. capsulatum, var. duboisii rarely involves the lungs but commonly involves the bones and skin. Var. duboisii is the causative agent of African histoplasmosis. Histoplamosis can be fatal to immunocompromised people. Chronic cavitary histoplasmosis is most commonly observed in individuals with underlying pulmonary disease.

Microsporum

Microsporum belongs to the group hyphomycetes and has about 17 different species. The natural habitat of this fungus is in soil, but it can be also found on animals and humans (from nails). It forms large, thick walled, septate, macrospores which are usually spindle-shaped. The genus Microsporum is one of the keratinophilic fungi classified as dermatophytes, although not all the species are pathogenic. Microsporum is the asexual phase (anamorph state) and the telemorph phase (sexual state) of this fungus is Arthroderma (ascomycete). The fungus causes infection in hair, skin or nails and can degrade keratin, thus can reside on skin and its appendages and remains noninvasive.

Mucor

Mucor belongs to the class zygomycetes and has about 40 different species. The fungus is found in soil, plant debris, and dung. In indoor, fungus may occur in vegetables, decaying fruits, and wet surfaces. It is a very fast growing fungus, produces erect sporangiophores that contains sporangiospores. Zygospores, if present arise from the mycelium. No species are known to produce mycotoxins. It causes zygomycosis (mucormycosis), an opportunistic human infection. Zygomycosis includes mucocutaneous and rhinocerebral infections, as well as septic arthritis, dialysis-associated peritonitis, renal infections, gastritis and pulmonary infections. Mucor spp. may cause infections in amphibians, cattle, and swine.

Myrothecium

Myrothecium belongs to the group hyphomycetes and has about 8 different species. It is found in soil, plants, and grasses. The fungus is occasionally found in indoor environment and grows on building materials made of cellulose. The fungus produces viscous dark green masses of spores on sporodochia. Whether the fungus is a human pathogen or causes allergy on humans is still unknown. The fungus is known to produce two mycotoxins (verrucarins and roridnins) belonging to trichothecene family.

Myxotrichum

Myxotrichum belongs to the class ascomycetes and has 7 different species. The fungus can be found in soil. In indoor, it occurs in paper substrates, damp drywall, decomposing materials. It produces black, mesh-like, setose ascocarps with small, fusiform ascospores.Myxotrichum deflexum produces a pinkish red diffusing pigment and may produce stains on paper surface. No reports of mycotoxins, pathogenicity, or allergy are known.

Nigrospora

Nigrospora belongs to the group hyphomycetes and has 5 different species. The fungus often found growing in soil and decaying plant material. It seldom found growing indoors. It forms very dark conidia, which are slightly longer in the horizontal axis and borne on very short sporogenous cells. No report of mycotoxin production is known. Some people may experience hay fever and asthma if large numbers of spores are inhaled.

Paecilomyces:

Paecilomyces belongs to the group hyphomycetes and about 35 different species. It is a cosmopolitan filamentous fungus which inhabits the soil, decaying plants, food products, paper, and tobacco. Some species of Paecilomyces are isolated from insects. They are important industrially as producers of citric and gluconic acids, and antifungal antibiotics (e.g. variotin). Some species are also important agriculturally as they can stimulate the growth of important crop seedlings like barley and corn. Paecilomyces is usually considered as a contaminant but may also cause infections in humans and animals. The genus Paecilomyces contains several species. The most common are Paecilomyces lilacinus and Paecilomyces variotii. The color of the colony and certain microscopic features help in differentiation of the Paecilomyces species from each other. Another feature that helps in species identification is thermophilicity. Paecilomyces crustaceus and Paecilomyces variotii are thermophilic and can grow well at temperatures as high as 50° and possibly 60°C. Paecilomyces species can cause various infections in humans. These infections are occasionally referred to as paecilomycosis. Corneal ulcer, keratitis, and endophthalmitis due to Paecilomyces may develop following extended wear contact lens use or ocular surgery. Paecilomyces is among the emerging causative agents of opportunistic mycoses in immunocompromised hosts. Direct cutaneous inoculation may lead to these infections. These infections may involve almost any organ or system of human body. Soft tissue, pulmonary, and cutaneous infections, cellulitis, onychomycosis, sinusitis, otitis media, endocarditis , osteomyelitis, peritonitis, and catheter-related fungemia have all been reported. Paecilomyces species can also cause allergic disorders, such as allergic alveolitis. Some species of Paecilomyces are known to produce mycotoxin patulin.

Penicillium

Penicillium belongs to the group hyphomycetes and has about 200 different species. It is one of the most commonly found mold and has great importance in the human environment. The fungus is found in soil, decaying plant debris, compost piles, and rotten fruit. Many of the species are known to cause food decay and others colonize various organic substrata. In indoor environment, the fungus can be found on growing dried foods, cheeses, fruits, herbs, spices, cereals, wood, and drywall, carpet, painted surfaces, wallpaper, and other household contents. Many species are known to produce mycotoxins, including penicillic acid (P. aurantiogriseum), viridicatin (P. viridicatum), ochratoxin (P. verrucosum), luteoskyrin (P. islandicum), rugulosin (P. variabile), penitrem A (P. crustosum), patulin and griseofulvin (P. griseofulvum), citrinin (P. citrinum), rubratoxin (P. crateriforme), etc. Potential mycotoxicoses from ingestion of moldy food and feed are significant hazards. Inhahation of spores containing mycotoxins is implicated as a contributing factor for Organic Dust Toxic Syndrome (ODTS) and Non-infectious Fungal Indoor Environmental Syndrome (NIFIES). Penicillium is also a proven causal agent of hay fever, allergy, asthma, and hypersensitity pneumonitis.

Petriella

Petriella belongs to the class ascomycetes. It is commonly found from plant material and dung in nature. In indoor, it is commonly found in wet wood, particularly common under kitchen sinks and bathrooms where there is relatively slowly on persistently wet wood. It produces a Graphium or Scedosporium in anamorph state. Petriella produces sticky cirrus of reddish brown ascospores at maturity from small black ascocarps. No reports of mycotoxins, pathogenicity, or allergy are known.

Peziza

Peziza belongs to the class ascomycetes. Peziza species are macrofungi commonly called cup fungi. In outdoor, it grows on woody materials. It is common in indoors, grows on a wide range of domestic materials including bathroom floors, plaster, cement, sand, coal dust, wet rugs, carpets, fireplace ashes, walls, kitchen counters, shower stalls, damp closets, behind refrigerators, around leaky water beds, in cellars, greenhouses, under porches, and in cars. These cup fungi have a rubbery texture and are large enough to pluck from carpets or baseboards with the fingers. It forms fruiting bodies (ascocarp) that are cup-shaped. Ascospores are produced in ascus. Cup fungi are most closely related to Helvella and the morels (Morchella). The most common species is Peziza domiciliana. No reports of mycotoxins, pathogenicity, or allergy are known.

Pithomyces

Pithomyces belongs to the group hyphomycetes and has about 15 different species. It grows in soil, decaying leaves and grasses. In indoor, this fungus can grow well on moist papers, drywall papers, and other materials made of cellulose. It produces dark, septate, rough walled spores on short stalks. It produces a mycotoxin, sporidesmin, however, its effect on humans are not studied. Similarly, pathogenicity or allergic reactions on humans are not known.

Rhizopus

Rhizopus belongs to the class zygomycetes and has about 12 species. It can be found in soil, decaying fruits and vegetables, dung, and compost. Rhizopus is a plant parasite and infects potato, cotton, and various fruits. In indoor, it can be found on spoiling food and old bread. They produce rhizoids and brown color sporangiophores which contains sporangiospores. They produce several antifungal compounds. Although Rhizopus spp. are plant parasites and are common contaminants, they are also occasional causes of serious infections in humans. They are known to cause zygomycosis.

Rusts

Rusts belong to the class basidiomycetes. They are very large group of fungi, have 14 families, 105 genera and more than 5000 species. Most of the rust are obligate parasites on plants (grasses, flowers, trees, and diverse group of other plants) and require two different hosts to complete their life cycle. They are not known to grow on general cellulose surfaces or building materials. They grow in indoor environments only when host plants are present. They produce urediospores, teliospores, basidiospores, and aeciospores. Basidiospores and aeciospores have an active spore release mechanism. Rusts are not known to produce mycotoxin. Inhaling large number of spores may cause hay fever and asthma.

Scopulariopsis

Scopulariopsis belongs to the group hyphomycetes. These species are commonly found in soil, decaying wood, and various other plant and animal products. In indoor environment Scopulariopsis is found on dry walls, cellulose board, wallpaper, wood, and mattress dust. Species of Scopulariopsis have also been isolated from carpets, hospital floor, swimming pool, wooden food packing, shoes and wood pulp. Scopulariopsis species are sometimes encountered growing on meat in storage. Some of the common species are S. brevicaulis, S. brumptii, S. candida and S. asperula. Annellophores arise singly or in groups and give rise to long chains of basally truncate spores. No species of this fungus are known to produce mycotoxins, but the most common species, S. brevicaulis, is able to degrade arsenic containing material, releasing free arsenic into the environment. Scopulariopsi brevicaulis is a well known agent of onychomycosis (nail infection).

Skin cells

Human skin is a protective, waterproof, and exceedingly useful organ. It is also constantly changing and regenerating itself. The skin helps to protect the body from injury; provides a shield against harmful substances and organisms such as bacteria and parasites; helps to keep moisture in the body; helps keep our body temperature constant; and has nerve endings that help you feel sensations.

Our skin is composed of several layers. The outer layer (that we can see) is called the epidermis. It's composed of cells made of keratin, a hard substance that also forms our hair and nails. In other species, keratin forms hooves, claws, horns, shells of turtles, spines of porcupines, etc. The individual cells are called keratinocytes.

New keratinocytes grow at the lowest level of the epidermis, which bonds with the next layer, the dermis. The new skin cells gradually push their way to the top layer. When they reach the top, they die and are "weathered" by the environment and our daily activities. The top "dead" layer is called the stratum corneum. Eventually, the dead cells break away from the epidermis and fall off, making room for newer cells growing up from below. It takes roughly one month for new cells to get all the way to the top layer, meaning the skin we have a month from today will be completely new compared to the skin we have now.

It is estimate that the human body is made up of around 10 trillion cells in total. Our skin makes up about 16 percent of your body weight, which means we have roughly 1.6 trillion skin cells. Of course, this estimate can vary tremendously according to a person's size. Of those billions of skin cells, between 30,000 and 40,000 of them fall off every hour. Over a 24-hour period, we lose almost a million skin cells.

Where do they all go? The dust that collects on our tables, TV, windowsills and on those picture frames that are so hard to get clean is made mostly from dead human skin cells. In other words, our house is filled with former bits of ourselves. In one year, we shed more than 8 pounds (3.6 kilograms) of dead skin. Our house is also filled with trillions of microscopic life forms called dust mites that eat our old dead skin. Most of us have no effect on dead skin cells when we inhale. However, some immunocompromised people can be sensitive to their own skin cells and show allergic reaction.

Smuts

Smuts belong to the class basidiomycetes. They have 2 families, about 50 genera, and 950 species. They are obligate parasites, growing on grasses, cereal crops, weeds, and other fungi and flowering plants. They can be found in indoor if host plants are present, but can also grow on general cellulose surfaces in the yeast state. Smuts are not known to produce mycotoxin. Inhaling large number of spores may cause hay fever and asthma.

Sporothrix

Sporothrix belongs to the group hyphomycetes and has about 40 species. Sporothrix schenckii is the active species. Ophiostoma stenoceras is the teleomorph of Sporothrix sp. The fungus is distributed worldwide and isolated from soil, living and decomposing plants, woods, and peat moss. It is a dimorphic fungus. At 25°C, colonies grow moderately rapidly. They are moist, leathery to velvety, and have a finely wrinkled surface. It produces hyaline spores on short denticles acrogenously on a simple sporogenous cell or directly from the vegetative hyphae. At 37°C, colonies grow moderately rapidly. They are yeast-like and creamy. It is not known to produce mycotoxin. Sporothrix schenckii is an occasional cause of human infections. The infection starts following entry of the infecting fungus through the skin via a minor trauma and may affect an otherwise healthy individual. Sporotrichosis (‘rose handler’s disease’) is primarily a chronic mycotic infection of the cutaneous or subcutaneous tissues and adjacent lymphatics characterized by nodular lesions which may suppurate and ulcerate.

Stachybotrys

Stachybotrys belongs to the group hyphomycetes and has about 15 different species. Commonly it is referred as ‘toxic black mold’. In outdoor, it is found on growing on soil, decaying plant substrates, decomposing cellulose material (hay, straw), leaf litter, and seeds. The fungus grows well in indoor materials containing wet cellulose such as drywall, paper, ceiling tile, jute, wood, wicker, and other materials made of straw. In nature, it produces black spores in sticky masses and are disseminated by insects. Air-borne spores become a more significant potential problem when the old growth dries or when it is disturbed by occupant activities and may cause Type I allergy. Stachybotrys chartarum is known as one of the most toxigenic species of mold and produces macrocylic trichothecenes mycotoxins such as verrucarin, roridin, satratoxin, sporidesmin, trichoverrol, clclosporins, and stachybotryolactone. Trichothecenes are known as cytotoxic compounds capable of killing cells and are carcinogenic. Stachybotrytoxicosis was one of the first mold mycotoxicoses to draw scientific study and paved the way for a broader understanding of the hazards posed by mycotoxin. Symptoms included irritation of oral/nasal passages and necrotic lesions of respiratory and digestive tracts, often fatal within 24 hour. The first case of human stachybotrytoxicoses was a result of inhalation exposure of the spores by handlers of contaminated hay and straw. The fungus has also been associated with pulmonary hemorrhage of several infants.

Stemphylium

Stemphylium belongs to the group hyphomycetes and has about 6 species. The fungus is often found growing in soil, wood, decaying plant matter. Some species are known to cause leaf diseases on certain plants. In indoor, fungus grows well on general cellulose surfaces and dusts. It produces conidiophores with dark, intercalary swellings bearing solitary, pigmented, muriform spores. Production mycotoxin by this fungus is not reported. Inhaling spores may cause hay fever and asthma.

Torula

Torula belongs to the group hyphomycetes and has about 12 species. It is a common outdoor mold and can be found on soil, dung, plant debris, sugar beet roots, oats, fresh and sea water. In indoor, the fungus can be found on materials containing cellulose such as jute, old sacking, wicker, wood and paper. It produces simple or branched chains of dark spores which arise more or less directly from the vegetative hyphae. The spores are round, ellipsoidal or sub-spherical, brown or olivaceous in color. Although some species of Torula are known to produce cytotoxic compounds, their effect on humans is not known. Inhaling large number of spores may cause hay fever and asthma.

Trichocladium

Trichocladium is a dematiaceous hyphomycetes and has about 18 species. It is a commonly occurring outdoor fungus and can be found on trees, soil, sand, other fungi. In indoor, the fungus can be found on materials containing cellulose wood and paper. The conidia (spores) have a distinctive morphology, brwon, thick-walled, one or more septate, more or less pyriform (pear-shaped) to clavate (club-shaped), elliptical, subglobose or obclavate in shape. The fungus may cause keratitis (inflammation of the eye's cornea) and known to produce mycotoxin known as Trichocladinols. These compounds have cytotoxic effects against two human tumor cell lines. Allergenicity has not been studied yet.

Ulocladium

Ulocladium belongs to the group hyphomycetes and has 9 species. The fungus can be found growing in soil, dung, paint, grasses, fibers, wood, decaying plant material, paper, and textile. In indoor, fungus can grow on cellulose containing materials such as drywall, ceiling tile, paper, paint, tapestries, and straw materials. It needs high moisture content to grow and reproduce. They produce large, multicelled, brown, and muroform spores. Production mycotoxin by this fungus is not reported. Inhaling spores may cause hay fever and asthma.

Wallemia

Wallemia belongs to the group hyphomycetes. Up to now, only one species (W. sebi) is described in the genus Wallemia. Wallemia sebi has been found to be very common in the agricultural environments. In outdoor, it is known to occur in soil and hay. It can be isolated from hypersaline water of man-made salterns on different continents. It is a xerophilic fungus, requiring very low moisture content. In indoor, W. sebi has been isolated from jams, dates, bread, dried food, cakes, salted beans and fish, bacon, fruits, and textiles. The fungus is known to produce mycotoxins including walleminol, tryptophol and UCA 1064-beta, but their effects on humans are not known. It is suspected to be one of the causes of farmer's lung disease. Inhaling spores may cause hay fever and asthma.