Microbial volatile organic compound emissions from Stachybotrys chartarum growing on gypsum wallboard and ceiling tile

Abstract

Background: Stachybotrys chartarum is a filamentous mold frequently identified among the mycobiota of water-damaged building materials. Growth of S. chartarum on suitable substrates and under favorable environmental conditions leads to the production of secondary metabolites such as mycotoxins and microbial volatile organic compounds (MVOCs). The aim of this study was to characterize MVOC emission profiles of seven toxigenic strains of S. chartarum, isolated from water-damaged buildings, in order to identify unique MVOCs generated during growth on gypsum wallboard and ceiling tile coupons. Inoculated coupons were incubated and monitored for emissions and growth using a closed glass environmental growth chamber maintained at a constant room temperature. Gas samples were collected from the headspace for three to four weeks using Tenax TA tubes.

Results: Most of the MVOCs identified were alcohols, ketones, ethers and esters. The data showed that anisole (methoxybenzene) was emitted from all of the S. chartarum strains tested on both types of substrates. Maximum anisole concentration was detected after seven days of incubation.

Conclusions: MVOCs are suitable markers for fungal identification because they easily diffuse through weak barriers like wallpaper, and could be used for early detection of mold growth in hidden cavities. This study identifies the production of anisole by seven toxigenic strains of Stachybotrys chartarum within a period of one week of growth on gypsum wallboard and ceiling tiles. These data could provide useful information for the future construction of a robust MVOC library for the early detection of this mold.

Figure 1

Experimental setup. The experimental setup allows for easily introducing the sorbent tubes into the sample loop without the need to open the growth chambers. A miniature pump draws the headspace from the chambers into the sorbent tube. The sample loop continues to a rotameter, where airflow is measured and is then transferred back into the growth chambers, thus providing a completely enclosed sample trajectory.

Figure 2

Anisole and 3-octanone emissions on gypsum wallboard. Anisole and 3-octanone emission was followed, as a function of time, during the growth of the different strains of S. chartarum on gypsum wallboard. The bar graph shows the mean ± SD of anisole and 3-octanone emissions.

Figure 3

Anisole and 3-octanone emissions on ceiling tile. The bar graph shows the mean ± SD of anisole and 3-octanone emissions for six independent Sc strains growing on ceiling tile. ^a.S. chartarum ATCC 208877 MVOCs emissions not tested on ceiling tile; ^b. 3-octanone emissions for S. chartarum ATCC 201210 below detection limit.