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Dr Jackson Kung'u- Mold Specialist

Dr Jackson Kung'u- Mold Specialist

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Dr. Jackson Kung’u (PhD)- Mold Specialist.
Phone: 905-290-9101

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Home | Fungi | Penicillium

Penicillium

Aspergillus/Penicillium in the Basement

Question: Is Aspergillus/Penicillium spore count in the basement high? We have this smell in our house for some time. We have also arranged for the gas company to come to see if there is gas leak. Last week, we had an air sample taken from our house. The Aspergillus/Penicillium reading from outside was 267 spores/m3 and the reading from the basement was 26,667 spores/m3. I do not know if these readings indicate any significance. Do you have any suggestions for the cause and solutions? Thank you very much for your help.

Answer: I think the Aspergillus/Penicillium spore count in the basement suggests persistent humid conditions. You may want to hire a professional to come and assess the extent of mold growth in the basement, identify the cause (i.e., moisture source) and suggest the best method to fix the moisture problem and remove the mold safely. To control the growth of mold such as Aspergillus/Penicillium the humidity in the basement has to be reduced to a level below 60%. The following techniques can help control moisture in the basement:

  1. Fix leaks, drips, and seepage problems.
  2. Dry wet areas within 24 to 48 hours to prevent mold growth. Thoroughly clean and dry water-damaged carpets and consider removal and replacement of items that appear to be permanently water damaged. Mold and mildew on hard surfaces can be washed and the surfaces dried completely.
  3. Do not finish a basement below ground level unless all water leaks are sealed. A finished basement should also have adequate outdoor ventilation and heat to prevent condensation.
  4. Operate a dehumidifier in the basement, if necessary, to keep relative humidity levels down. But keep in mind a dehumidifier can be expensive to operate.

Filed Under: Aspergillus, Fungi, Indoor Air Quality, Penicillium, Public Questions Tagged With: aspergillus penicillium, mold and mildew, mold growth, spores

Mold Growth, Moisture, and Your Home

Moisture is one of the key requirements for mold growth in homes. There are different types of mold. Some molds require relatively very low levels of available moisture for them to grow. These types of mold are referred to as xerophilic and are likely to be found in almost every home. The common xerophilic fungi belong to the genera Aspergillus, Penicillium and Wallemia. Some other molds require wet or highly damp prolonged conditions. These are referred to as hydrophilic (“water loving”) fungi and their presence in homes is an indication of moisture damage. Examples of indicators of moisture damage include Chaetomium, Stachybotrys and Fusarium.

Mold growth: Penicillium on wood

Mold growth: Penicillium on wood

 

Mold Growth Control

The best way to control mold growth is to eliminate moisture. Strategies to control mold growth involve:

  • Reducing humidity. It’s recommended that relative humidity be maintained at or below 60%.
  • Inspect the building regularly for signs of mold, moisture, leaks, or spills and take appropriate action
  • Respond promptly when you see signs of moisture and/or mold, or when leaks or spills occur
  • Reduce potential for condensation on cold surfaces such as windows, piping, exterior walls, roof, or floors by adding insulation
  • Frequently clean floor, carpet, and remove dust on surfaces. This reduces the amount of spores that would otherwise start new mold growth when moisture becomes available.

Filed Under: Aspergillus, Chaetomium, Fungi, Fusarium, Penicillium, Stachybotrys Tagged With: fungi, fungus, moisture, mold

Wood Rot Fungi

What are wood rot fungi? Wood is one of the major components of building materials in residential and office buildings. In fact it’s almost impossible to miss a wooden item in a building. It is subject to attack by wood rot fungi and other organisms if it’s not well preserved.

Growth Requirements for wood rot fungi

For fungi to colonize wood, the following conditions are required:

  • Favourable temperatures. Generally wood colonizing fungi have optimal growth temperature at aound 25 degrees Celsius.
  • Adequate moisture. Moisture is the most critical requirement for fungi to colonize wood. Fungi will not attack dry wood (i.e., with a moisture content of 19 percent or less). Decay fungi require a wood moisture content of about 30%.
  • Adequate oxygen. Most fungi require (oxygen) for growth.
  • Food source. Like every other living organism, fungi require nutrients for growth. These are readily available on wood surfaces in form of dust. The wood itself is made of biodegradable compounds (cellulose, hemicellulose,lignin).

wood rot fungiThere are 2 groups of wood rot fungi. These are the wood-decaying fungi (wood-rotting fungi) and the Wood-staining fungi (sapstaining fungi).

Wood rot fungi
The wood-decaying fungi are the most damaging of all the wood destroying fungi. These fungi are prolific producers of strong enzymes that they use to breakdown complex wood components (cellulose, hemicellulose,lignin) to simple sugars that they can utilize as food.

Wood-decaying fungi

Wood-decay fungi colonize the sapwood and heartwood of most tree species. These fungi grow inside the wood and/or on wood surfaces. On the wood surface they appear as fan-shaped patches of fine, threadlike, cottony growths or as rootlike shapes. The color of these growths may range from white through light brown, bright yellow, and dark brown. The spore-producing structures (fruiting bodies) of the fungus may take the form of mushrooms, shelflike brackets, or flattened, crustlike structures. Fine, threadlike fungal strands called mycelia grow throughout the wood and excrete enzymes that digest parts of the wood as food. By breaking down the cellulose, hemicellulose,and lignin wood the strength and other properties of the wood are destroyed.

The rate of decay and extent of deterioration depend on the duration of favorable conditions for fungal growth. Decay will stop when the moisture content is lower than the fungu’s requirements. Decay slows down significantly if the temperature of the wood is either too low or too high. Early decay is more easily noted on freshly exposed surfaces of unseasoned wood than on wood that has been exposed and discolored by the weather. Wood decay fungi are generally grouped into three major categories: brown rot, white rot, and soft rot.

Brown Rot

Brown rot fungi such as Poria monticola and Serpula lacrymans break down primarily the cellulose component of wood for food,leaving a brown residue of lignin. Wood severely infested with brown rot fungi is greatly weakened even before decay is visible. Advanced stages of brown rot infestation are characterised by:

  • The dark brown color of the wood
  • Excessive shrinkage
  • Cross-grain cracking
  • The ease with which the dry wood substance can be crushed to a brown powder.

Brown rot fungi are probably the most important cause of decay of softwoods used in aboveground construction in North America. Brown rot-decayed wood, when dry, is sometimes called “dry rot.”

A few fungi such as Serpula lacryman can decay relatively dry wood by using water-conducting strands (rootlike structures called rhizomorphs) that can carry water from damp soil to wood in lumber piles or buildings. These fungi can decay wood that otherwise would be too dry for decay to occur. They are sometimes called the “dry rot fungi” or “waterconducting fungi.”

White Rot

The white rot fungi, Phellinus megaloporus and Poria contigua, break down both lignin and cellulose in wood. They have a bleaching effect that may make the damaged wood appear whiter than normal. Affected wood shows normal shrinkage and usually does not collapse or crack across the grain as with brown rot damage. However, the infested wood loses its strength gradually until it becomes spongy to the touch. White rot fungi usually attack hardwoods, but several species can also cause softwood decay.

Soft Rot

penicillium on woodSoft rot fungi such as Chaetomium globosum usually attack very wet wood, causing a gradual and shallow (3-4 mm) softening from the surface inward that resembles brown rot. The infested wood surface darkens and becomes very soft, hence the name soft rot.

Wood-staining fungi

Unlike the wood-decay fungi, wood-staining fungi are only a cosmetic problem. They tend to grow on the surface of wood. Examples of wood staining fungi include Ceratostomella spp. and Diplodia spp. These fungi penetrate and discolor sapwood, particularly of softwood species. Typical sapstain, unlike staining by mold fungi, cannot be removed by brushing or planing. Sapstain fungi may become established in the sapwood of standing trees, sawlogs, lumber, and timbers soon after they are cut and before they can be adequately dried. The strength of the wood is not greatly affected, but the wood may not be fit for use where appearance is important (such as siding, trim, furniture, and exterior millwork that is to be clear-finished).

Superficial Wood Colonizing Fungi

Superficial wood colonizing fungi such as Fusarium spp and Penicillium spp., first become noticeable as green, yellow, brown, or black, fuzzy or powdery surface growths on the wood surface. The colored spores they produce can usually be brushed, washed, or surfaced off. On openpored hardwoods, however, the surface molds may cause stains too deep to be easily removed. Freshly cut or seasoned wood stockpiled during warm, humid weather may be noticeably discolored with mold in less than a week. Molds do not reduce wood strength, but they can increase the capacity of wood to absorb moisture, thus increasing the potential of attack by decay fungi.

Filed Under: Fungi, Fusarium, Penicillium, Phellinus, Poria, Serpula, Wood Decay Fungi Tagged With: Biodeterioration, fungi, wood, wood rot

Biodeterioration

Biodeterioration is a terminology used to describe any undesirable change in the properties of a material caused by the vital activities of organisms.

Fungal growth requires suitable temperature, moisture and air (oxygen). Fungi are heterotrophs that acquire nutrients by absorption. They secrete hydrolytic enzymes (exoenzymes) and acids to decompose complex molecules into simpler ones that can be absorbed and used as nutrients. Hence, they are believed to be potential contributors to biodeterioration of different kinds of materials containing cellulose, silicate mineral (mica and orthoclase), iron and magnesium-bearing minerals (biotite, olivine, pyroxene) etc.

Fungi cause biodeterioration to many materials including:

  • building materials
  • animal feeds
  • electrical equipment
  • food including meat, fruits and grains
  • fuel including jet fuel
  • glass and optical equipments
  • gunpowder
  • leather
  • monuments
  • paint
  • paper
  • tobacco etc.

 How are Fungi involved in biodeterioration?

The rate of biodeterioration depend on prevailing environmental conditions and the fungus involved. There are different mechanisms of biodegradation. These include microbial corrosion, hydrocarbon degradation and biodegradation of cellulose.  Aspergillus niger, Chaetomium globosum, Scopulariopsis brevicaulis, Trichoderma koningii, Trichothecium roseum and Eurotium chevalieri are cellulolytic fungi. Their efficiency to degradate cellulosic (cellulose containing) materials is due to their ability to produce large amounts of cellulase enzymes. 

Stachybotrys chartarum is a common fungus growing on paper (such as that covering gypsum wallboard) in damp buildings.

Some fungi cause blue stain and soft rot of wood, discolouration and loss of strength of cotton materials.  Many fungi spoil food in storage. Aspergillus flavus grows on peanuts and many other substrates, producing a mycotoxin called aflatoxin, which contaminate food and causes liver damage. Fusarium graminearum grows on feed corn and produces the  mycotoxin zearalenone that causes oestrogenic syndrome in animals.

Through the action of excreted oxalic and citric acids fungi can deteriorate marble, limestone, granite and basalt. Several species of fungi are involved in biodeterioration of stone monuments in different countries. Some of these fungi are Aspergillus elegans, Aspergillus flavus, Aspergillus nidulans, Aspergillus niger, Aspergillus versicolor, Alternaria sp, Cladosporium cladosporioides, Cladosporium sphaerospermum, Cunninghamella  echinulata, Curvularia lunata, Fusarium roseum,  Gliocladium virens, Penicillium crustosum, Penicillium glabrum, Penicillium chrysogenum (=Penicillium notatum), Rhizopus arrhizus.

Biodeterioration is a problem worldwide. Several control measures have been applied to prevent the biodeterioration. These include use of fungicides, biological control, prevention of biodeterioration by control of environmental conditions, periodic cleaning of dirt, dust and spores, and use of radiation.

Filed Under: Alternaria, Aspergillus, Biodeterioration, Chaetomium, Cladosporium, Cunninghamella, Curvularia, Fungi, Fusarium, Gliocladium, Penicillium, Rhizopus, Scopulariopsis, Stachybotrys, Trichoderma, Trichothecium Tagged With: Biodeterioration, control., fungi

Black Mold Growth In Buildings

The black mold, Stachybotrys chartarum, is the mold feared most by the general public. It’s one of the molds used as indicators of moisture damage in a building. Black mold thrives on wet materials rich in cellulose. It’s commonly isolated from soil and decaying plant matter such as straw. In buildings black mold is found growing on very wet gypsum board, wallpaper, cotton fabrics and textiles,  and other materials containing cellulose.

Unlike some other indoor molds such as Aspergillus and Penicillium that produce dry spores, spores of black mold (Stachybotrys) are produced in wet form. This means that the spores of Stachybotrys do not easily become airborne until they dry out or get disturbed say during renovations. Therefore, if pre-remediation air samples, for example, contain a few spores of black mold, it’s important to try and locate the source of those spores. The mold is most likely to be located in areas with a history of moisture damage.

Medical Significance Of Black Mold

While black mold is highly publicized as the cause of all sorts of health problems, it’s medical significance still remains controversial.

Filed Under: Aspergillus, Fungi, Penicillium, Stachybotrys Tagged With: Black mold

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