chaetomium - Mold Bacteria Consulting Services

My Mould Test Results Said Phoma: Is Phoma dangerous?

This is one of the questions we received recently from one of our web visitors. Phoma is one of the moulds that may be found in water damaged buildings. Other common fungi in water damaged buildings include Chaetomium globosum, Stachybotrys chartarum, Ulocladium chartarum, Trichoderma spp such as Trichoderma harzianum, Aureobasidium pullulans, and the yeast fungus Rhodotorula spp.

In nature, Phoma is widespread in soil and a wide range of plants and plant materials. It is one of the most important plant disease causing agents. In indoor environment, Phoma is common on wet/damp paints, wood, wall papers, window frames, and caulking especially in bathrooms. Species of Phoma are also commonly isolated from house dust. The common species in indoor environment are Phoma glomerata and Phoma macrostoma.

Phoma species are mainly contaminants, though may rarely cause infections in humans particularly to individuals with weak immune system. They are not known to pose an inhalation hazard to humans. However, any mould growing in human occupied environment should be treated as potentially hazardous.

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Stachybotrys And Ulocladium: Indicators Of Moisture Problem In A Building

Jackson Kung'u

Stachybotrys chartarum and Ulocladium chartarum Different categories of moulds have different water requirements. Some moulds such as Stachybotrys, Ulocladium, Acremonium, Fusarium, Trichoderma and Chaetomium thrive well on very wet building materials. Some of these moulds have come to be associated with water damaged buildings and their presence in a building is an indication of a moisture problem.

The picture on the right shows both Stachybotrys chartarum and Ulocladium chartarum on the same lift tape sample taken from a water damged building. Stachybotrys is also commonly found together with Chaetomium spp, particularly Chaetomium globosum.

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Health Problems Associated with Indoor Moulds

Jackson Kung'u

Exposure to indoor mould has been associated with the following health problems:

respiratory symptoms such as coughing, wheezing
respiratory infections such as aspergilloses
allergic diseases, including allergic asthma and bronchitis
unspecific symptoms, e.g., eye and skin irritation, fatigue, headache, nausea, and vomiting.

The moulds most frequently encountered in indoor environment are Penicillium, Aspergillus, Chaetomium, Ulocladium, Stachybotrys, Cladosporium, Acremonium, Mucor, Paecilomyces, Alternaria, and Trichoderma. These moulds are all known to cause different types of inhalation allergy. Some moulds such as Chaetomium, Stachybotrys and Ulocladium thrive under very wet conditions. Their presence in indoor environment is an indication of water problem.

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Occurrence of the Mould Chaetomium in Indoor Environment: What Are the Implications?

Jackson Kung'u

Chaetomium is a cellulose degrading mould commonly found in soil, air, and decaying plant material. There are several species of Chaetomium. The most common ones are Chaetomium atrobrunneum, Chaetomium funicola, Chaetomium globosum, and Chaetomium murorum. In indoor environment the most common species of Chaetomium is Chaetomium globosum. Presence of Chaetomium species in indoor environment is a sign of serious water problem. Chaetomium may occur together with other water-loving moulds such Fusarium, Stachybotrys and Ulocladium. Species of Chaetomium are known to produce mycotoxins but to what extent these toxins contribute to poor indoor air quality or affect human health is not documented. In the medical literature some species have been reported to cause disease in immuno-compromised individuals.

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What Are Some Of The Mycotoxins Producing Indoor Moulds?

Jackson Kung'u

Growth of mould on building materials is determined by the water activity (a_w) among other factors. The a_w is a measure of the moistness of the material. Some moulds are capable of growing over a wide range of a_w but there is always an optimal range. While these moulds grow, they reach a stage when they produce mycotoxins depending on the growth conditions. Some of the indoor moulds that produce mycotoxins are discussed below.

Stachybotrys chartarum
Stachybotrys chartarum is cosmopolitan and grows naturally on straw and other cellulose containing materials in soil. In the indoor environment, this mould is commonly found together with other water-loving moulds on cellulose containing materials including paper, canvas and jute which are wetted to a water activity > 0.98. Stachybotrys chartarum produces a number of mycotoxins inclduding macrocyclic trichothecenes, satratoxins and roridins when growing on building materials. The optimum temperature for growth of Stachybotrys chartarum is 23 ^oC with a minimum and maximum temperature of 2 and 37 ^oC respectively. The optimal water activity is 0.98 with a minimum at 0.89.

Aspergillus flavus
Aspergillus flavus is widely distributed in soil. It is associated with a wide range of stored products such as maize and nuts. In indoor environment it is commonly found on damp walls, wallpaper, floor and carpet dust, tarred wooden flooring, humidifiers and HVAC fans, bakeries, shoes, leather, and bird droppings. Strains of this mould may produce mycotoxins such as aflatoxin, a class 1 carcinogen. The minimum and maximum temperatures for growth are 6 and 45 ^oC, with an optimum at 40 ^oC. The minimum water activity is 0.78 and an optimum at 0.98.

Aspergillus fumigatus
Aspergillus fumigatus is common in composting plant material, woodchips and garbage. Also common in dust infiltrating from outdoor air, carpet and mattress dust, wet building and finishing material, HVAC insulations, fans, filters, humidifier water and potted plant soil. A. fumigatus is a producer of various mycotoxins including gliotoxin, verrucologen, fumitremorgin A & B and fumigaclavines among others. A. fumigatus has an optimum growth temperature at 43 ^oC and minimum and maximum at 10 and 57 ^oC respectively. Minimum water activity for A. fumigatus is 0.82 and the optimum is 0.97.

Aspergillus niger
Aspergillus niger is found worldwide in soil and plant litter. In indoor environment A. niger is common in floor, carpet and mattress dust, acrylic paint, UFFI, leather, HVAC filters and fans, and potted plant soil. A. niger produces mycotoxins such as malformins and a few strains also produce ochratoxin A. A. niger requires a minimum temperature for growth of 6 and maximum of 47 ^oC with an optimum at 37 ^oC.

Aspergillus versicolor
Aspergillus versicolor is very common on gypsum board, floor, carpet, mattress and upholstered-furniture dust, and damp walls. A. versicolor produces high quantities of the carcinogenic mycotoxin, sterigmatocystin at water activities (a_w) above 0.95. A. versicolor is generally xerophilic- meaning that it can grow at low water activity (< 0.8). The minimum and maximum growth temperatures for A. versicolor are 4 and 40 ^oC with an optimum at 30 ^oC. Its optimal water activity is 0.95 with a minimum at 0.75.

Penicillium chrysogenum
Penicillium chrysogenum is one of the most common indoor moulds. It’s not known to produce highly potent mycotoxins. It is extremely common on damp building materials, walls and wallpaper; floor, carpet mattress and upholstered-furniture dust. P. chrysogenum produces few detectable metabolites and often none when growing on building materials. Lack of observed effects on persons exposed to high quantities of spores and the production of few metabolites suggest this species may not be an important health hazard. However, some strains may cause allergenic reactions to susceptible individuals. P. chrysogenum can grow at a minimum temperature of -4 ^oC, an optimum of 28 ^oC, and a maximum of 38 ^oC. It has minimum water activity of 0.79 and an optimum at 0.98

Penicillium brevicompactum
Penicillium brevicompactum is common on damp walls and building materials e.g., gypsum board; floor, carpet, mattress and upholstered-furniture dust. P. brevicompactum produces mycophenolic acid. P. brevicompactum can grow at -2 and 30 ^oC with an optimum at 25 ^oC. Its water activity requirements are a minimum of 0.75 and an optimum at 0.96.

Chaetomium globosum
Chaetomium globosum is common on cellulose containing building materials that has been very wet such as gypsum board, cellulose board and wood. Species of the genus Chaetomium are known to produce mycotoxins. C. globosum produces high quantities of chaetoglobosins. C. globosum requires a water activity of >0.90.

Trichoderma species
Trichderma species are frequently found on gypsum board and water saturated wood; floor, carpet and mattress dust; paint; domestic water supply, and HVAC system air. In one study, Trichoderma species were not found to produce detectable quantities of trichothecenes when growing on building materials. Less than 1% of the isolates produced trichodermol or its esters.

References
Kuhn, D. M. and Ghannoum, M. A. (2003). Indoor Mold, Toxigenic Fungi, and Stachybotrys chartarum: Infectious Disease Perspective. Clinical Microbiology Reviews, 16(1):144–172.Nielsen, K.F, (2002).

Mould growth on building materials: Secondary metabolites, mycotoxins and biomarkers, Dissertation, The Mycology Group, Technical University of Denmark. 116p

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