Mould growth on building materials - Statens Byggeforskningsinstitut

2.4.10 Paecilomyces
From the genus Paecilomyces Bain. two species are found in water damaged buildings, P.
variotii Bain. and P. lilacinus (Thom) Samson, with the first being the most abundant.
P. variotii is capable of growing on very low nutrient substrates as optical lenses, whereas P.
lilacinus seems to prefer protein rich media 270 .
P. variotii can produce the strongly cytotoxic mycotoxins patulin and viriditoxin 65 as well the
metabolites: ferrirubin, variotin, fusigen and indole-3-acetic acid 25 .
2.5 Biomarkers of mould <strong>growth</strong>
As earlier mentioned, not all spores are viable and hence a number of methods for measuring
chemical and molecular biological markers are needed. These methods can also provide
much faster measurements for mould determination and significantly better quantification.
For determination of moulds, four different principles can be used for material samples or air
filters:
• Determination of the activity of fungal enzymes. Here two methods have been used:
i) Fluorescein diacetate hydrolytic activity (by determining fluorescein) will both detect the
presence of bacteria and/or moulds in wooden samples 125,313 ; ii) Determination of the activity
of β-N-acetylglucosaminidase 314 (a enzyme in the chitinase partway) which is now
commercially available as the Mycometer Test TM . Both methods have the advantage that
the samples can be incubated for as long time as wanted, and hence a very high sensitivity
can be obtained as many molecules of reactant can be obtained from each enzyme
molecule. However these methods only detect functional enzymes.
• Chemical markers, which can be genus, species, or isolate specific. These include:
i) extracellular polysaccharides from Penicillium and Aspergillus 30,315 ;ii) 18:2ωphosphorlipid
fatty acids 314 ;iii) β-glucan from the cell wall, also being an important inflammatory
marker 37,39 ; iv) mycotoxins or secondary metabolites who are species specific
47 ; v) MVOC's in the air 41,316 ; vi) chitin from the cell wall 317 ; and finally the cell membrane
material ergosterol 318,319 •
. All these metabolites can principally be detected using
various analytical methods as described for metabolites in section 2.6.
PCR-based methods, detecting specific parts of the fungal DNA, enabling even isolate
recondition if needed, and also recently quantitation 229 . These methods will undoubtedly
be very important in the future especially when the DNA-chip technology comes
down in price.
• Bioassay detection, either by detection cytotoxicity 320,321 or more specific mode of action,
as the protein translation inhibition which is highly selective against trichothecenes
322 . Such methods give health relevant data but do not give any information on the
producing mould.
All these methods are significantly faster than cultivation techniques and can also detect
dead spores and mycelia, and will be the predominant methods in the future.
2.5.1 Ergosterol
Ergosterol (Erg) is the predominant compound in the fungal cell membrane, making it a suitable
indicator for fungal <strong>growth</strong>, although it should be noted that also some amoebae and
green algae are capable of producing Erg 323 .
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