Mold Bacteria Consulting Services

Serving Ontario and British Columbia

You are here: Home / Archives for Penicillium chrysogenum

Moulds commonly found in carpet and mattress dust

A number of moulds are frequently found in carpet and mattress dust. Eurotium repens is the most frequently detected mould in mattress dust. Others include Aureobasidium pullulans, Alternaria alternata, Penicillium chrysogenum, Aspergillus penicilloides and Aspergillus restrictus.

More than 100 species of moulds have been recorded from carpet dust. As with mattress dust, the most frequently isolated mould in carpet dust is Eurotium repens. The others are Penicillium chrysogenum, Alternaria alternata, Aureobasidium pullulans and Phoma herbarum.

Concentrations of these moulds in carpet and mattress dust can be as high as 70 million colony forming units per gram of dust. Such high concentrations of moulds are likely to cause respiratory allergy or irritating symptoms. Therefore, it is import to regularly HEPA vacuum the carpets, mattresses and upholstered furniture to reduce the dust and spore concentration. If people are suffering from reoccurring respiratory allergy or irritating symptoms in a building where there is no visible mould, it is suggested that dust be tested for the types and concentrations of mould present.

Penicillium Species As Indoor Air Contaminants

In 1928, Alexander Fleming’s bacterial cultures were contaminated by airborne spores of a green mould. Fleming noticed that bacteria were not growing close to the green mould. He concluded that the mould was producing a compound that was killing or inhibiting the growth of bacteria. That is how Penicillins, the oldest and probably the best known of all the antibiotics were accidentally discovered. The green mould was later identified as Penicillium notatum. Penicillium notatum (now called Penicillium chrysogenum) is one of the most common indoor fungal contaminants.Spores of Penicillium chrysogenum

Penicillium is found worldwide. The spores of this mould are found everywhere in the air and soil. In indoor environment, this mould proliferates in damp conditions. Penicillium is commonly called the blue or green mould because (depending on the species) it produces enormous quantities of greenish, bluish or yellowish spores which give it the characteristic colour. The blue in the blue-cheese, for example, is the colour of the spores of the Penicillium species used in ripening the cheese. About 200 species have been described.

Penicillium species as contaminants of indoor air

In indoor environments, Penicillium is extremely common on damp building materials, walls and wallpaper, floor, carpet mattress and upholstered furniture dust. The spores of this mould are produced in dry chains and are exposed to the air hence their ease to become airborne. Spore sizes range from 3 to 5 micrometres. Because of their small size, they take long to settle and can be inhaled deep into the lungs. The spores are found indoors throughout the year. For air samples analysed by direct microscopy, it is hard to distinguish between spores of Penicillium from those of Aspergillus. Therefore these spores are often reported as Aspergillus/Penicillium. The most common Penicillium species in indoor environment is Penicillium chrysogenum. It produces a number of toxins of moderate toxicity. It is also allergenic and can infect immuno-compromised patients.
Picture of Penicillium chrysogenum on wood

Penicillium species as a health hazard

Many species of Penicillium are common contaminants on various organic materials and are recognized potential mycotoxin producers. The most well known toxin producing species in foods include P. citreonigrum, P. citrinum, P. crustosum, P. islandicum and P. verrucosum. Therefore, when it comes to food contamination, correct identification of Penicillium is important. Although, human pathogenic species are rare, opportunistic infections have been reported in individuals with weakened immune system such as the HIV/AIDS patients. The species commonly associated with opportunistic infections is P. marneffei.

Penicillium species as food spoilage organisms

Penicillium species are common causes of spoilage of fruits, cheese, cold meats, old sandwiches, cereals and cereal products and a host of other agricultural and animal products. For example, Penicillium italicum and Penicillium digitatum are common causes of rot of citrus fruits, while Penicillium expansum is known to spoil apples. As mentioned above, most Penicillium species produce toxins. It is a good practice to discard foods with any visible mould growth. It is important to know some species of Penicillium are beneficial to humans. For example, cheeses such as Roquefort, Camembert and others are ripened with species of Penicillium.Penicillium on food

References

  1. Introduction to food and airborne fungi. Seventh Edition. Samson, Robert A., Hoekstra, Ellen S., Frisvad, Jens C (Editors). Centraalbureau voor Schimmelcultures, 2004.
  2. Microorganisms in home and indoor work environments: Diversity, Health Impacts, Investigation and control. Flanning Brian, Samson, Robert A., and Miller, David J (Ed.), Tayler and Francis, 2001.

For more information on Penicillium species,please visit http://www.moldbacteria.com/learnmore/moldlist.html or call 905-290-101.

Cladosporium: A Common Allergenic Indoor Mould

Cladosporium is a leaf mould and one of the most common in outdoor and indoor air worldwide. It is a very common household mould in bathrooms, around tubs, shower stalls, or window frames and even bathroom walls and ceilings.  Like every other mould, it requires free water for growth.  Around the edge of the tub there is water from splashing or water running down the wall from the shower.  The water just sits around the edge of the tub and may evaporate very slowly.  On walls and ceilings  the steamy air results in condensate, especially on colder, outer walls.  The spores are ubiquitous and will germinate in this available water and  very quickly little dark brown colonies start to grow.  Eventually there will be an olive-brown to blackish brown growth of Cladosporium around the tub.

Some species of Cladosporium cause serious diseases to plants. The mold is commonly isolated from air, soil, foodstuffs, stored fruits, cereal grains, groundnuts, paint, and textiles. Cladosporium is a well known allergenic mould. The most common Cladosporium species in outdoor air are Cladosporium cladosporioides and Cladosporium herbarum. During summer there can be very high concentrations of airborne spores of Cladosporium cladosporioides and Cladosporium herbarum, and both contain allergenic proteins in their spores. Cladosporium cladosporioides and Cladosporium hebarum may be found colonizing painted metal surfaces of covering panels and vents of heating, air conditioning and ventilation systems.Cladosporium sp.

Cladosporium sphaerospermum is the most predominant species growing in buildings. Studies have shown it can outgrow Penicillium chrysogenum because of its ability to re-initiate growth from the hyphal tips much faster than Penicillium species. Cladosporium sphaerospermum and occasionally Cladosporium herbarum is frequently isolated from indoor surfaces such as in bathrooms, windowsills and damp painted surfaces. It is also commonly found colonizing wood.

Species of Cladosporium are not known to produce any serious mycotoxins.

Do you have a mould question? Send it to My Question.

The Bright Side of Mould

In recent years we have been hearing a lot concerning the health effects associated with mould. Few people would think of the numerous benefits we get from mould.

First, mould contributes immensely to the decomposition of organic matter hence helping in recycling of nutrients. Imagine the mountains of garbage we could be having (unless we burn it) without the help of mould and other soil micro-organisms. Moulds also play an important role in waste treatment and the breaking down of pesticides.

Mould Contribution to Food Industry

Hardly do we think the mushrooms that we so much enjoy eating belong to the same group as the moulds, i.e., the fungi. As a small boy, we used to eat the smutted inflorescence of sorghum. I can only imagine the billions of spores of the fungus we ate and probably helped in spore dispersal. We never got sick! What about our favourite blue cheese? Some people may not be aware that it is made with the help of a mould called Penicillium roquefortii. Other cheeses such as Camembert and Brie are ripened by Penicillium camembertii. Some sweet wines such as the Sauternes are made from grapes infested by a mould called Botrytis cinerea. In the Far East there are a number of popular foods and sauces processed with the help of moulds. Tempeh for example is made by inoculating soybean with Rhizopus oligosporus and leaving the mould to colonize the soybean for some time. A high-protein meat-like product called ‘Qourn’ is made from a strain of Fusarium venenatum.

Mould Contribution to Human and Veterinary Medicine

Probably not many people know that the first antibiotic ever, penicillin, discovered by Sir Alexander Fleming in 1927, is produced by moulds within the genus Penicillium (primarily Penicillium chrysogenum). There are other antibiotics, antifungal compounds, cholesterol-reducing drugs, immunosuppressant compounds, and important enzymes from moulds.

Mould Contribution to Crop Protection

Some moulds have been used successfully in biological control of agricultural pests and diseases. Fusarium oxysporum fsp. cannabis, for example, is used as bioherbicide against marijuana plants while Beauveria bassiana is widely used in formulation of bio-insecticides.

Do you have a question on mould? Send it to My Question.

What Are Some Of The Mycotoxins Producing Indoor Moulds?

Growth of mould on building materials is determined by the water activity (aw) among other factors. The aw is a measure of the moistness of the material. Some moulds are capable of growing over a wide range of aw 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 (aw) 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

Should you have a question concerning mycotoxins or indoor moulds or bacteria, please send your question to My Question.

Salmonella food poisoning and symptoms

Salmonella food poisoning has been a growing concern in recent news. It has frequently lead to recalls of beef, salads and organic products and, even peanut butter products. Salmonella food poisoning occurs when one eats raw or undercooked foods such meat, poultry, eggs or egg products. Properly cooked food can get contaminated with Salmonella if […]

Legionella pneumophila – Guidelines for Laboratory Interpretation

Legionella pneumophila is a Gram negative, aerobic bacteria that is characterized as an opportunistic pathogen. It is the cause of Legionnaires’ Disease, a severe form of pneumonia and, it is the cause of Pontiac fever, a non-pneumonic form of L. pneumophila infection. Legionella spp.’s mode of transmission is through aerosols or aspiration of contaminated water. The Public Health […]

The Indoor Mold Is An Early Warning Device

The mold (or mould, in the Queen’s English) has been the victim of a bad press. Mention the word and it conjures up an image of something rotting or in the process of decomposition. And yet, were it not for the mold that inspired the discovery of penicillin millions of lives would have been lost. […]