Abstract
Stachybotrys (S.) chartarum had been linked to severe health problems in humans and animals, which occur after exposure to the toxic secondary metabolites of this mold. S. chartarum had been isolated from different environmental sources, ranging from culinary herbs and improperly stored fodder to damp building materials. To access the pathogenic potential of isolates, it is essential to analyze them under defined conditions that allow for the production of their toxic metabolites. All Stachybotrys species are assumed to produce the immunosuppressive phenylspirodrimanes, but the highly cytotoxic macrocyclic trichothecenes are exclusively generated by the genotype S of S. chartarum. In this study, we have analyzed four genotype S strains initially isolated from three different habitats. We grew them on five commonly used media (malt-extract-agar, glucose-yeast-peptone-agar, potato-dextrose-agar, cellulose-agar, Sabouraud-dextrose-agar) to identify conditions that promote mycotoxin production. Using LC-MS/MS, we have quantified stachybotrylactam and all S-type specific macrocyclic trichothecenes (satratoxin G, H, F, roridin E, L-2, verrucarin J). All five media supported a comparable fungal growth and sporulation at 25 °C in the dark. The highest concentrations of macrocyclic trichothecenes were detected on potato-dextrose-agar or cellulose-agar. Malt-extract-agar let to an intermediate and glucose-yeast-peptone-agar and Sabouraud-dextrose-agar to a poor mycotoxin production. These data demonstrate that the mycotoxin production clearly depends on the composition of the respective medium. Our findings provide a starting point for further studies in order to identify individual components that either support or repress the production of mycotoxins in S. chartarum.
Highlights
Stachybotrys (S.) chartarum is the most frequently isolated species of the genus Stachybotrys [1,2] and had been isolated from dead plant materials and other cellulosic, and water damaged substrates [3–6]
The genotype S had been implicated in several types of disease, such as stachybotryotoxicosis in animals, hemorrhage in human infants, and the sick building syndrome [13–23] Stachybotryotoxicosis may occur after oral uptake in horses as well as in cattle and sheep [19,20,24]
The four genotype S strains grew well and showed comparable sporulation levels on all five solid media (Figure S1). The latter is important since mycotoxin production and sporulation are assumed to be linked in S. chartarum [35]
Summary
Stachybotrys (S.) chartarum is the most frequently isolated species of the genus Stachybotrys [1,2] and had been isolated from dead plant materials (e.g., herbs, straw, and hay) and other cellulosic, and water damaged substrates (e.g., wallpaper, plasterboard, or wooden lining) [3–6]. Fungi 2020, 6, 159 hemorrhage in infants or symptoms related to the sick building syndrome complex, mainly due to fungal growth on building materials after water damages [21–23] It is surprising how little is known about the influence of nutritional factors on their production. Building materials and natural habitats of S. chartarum genotype S are too complex media to identify limiting nutritional factors. Factors such as temperature and humidity are already known to influence the MCT production [6,28,29]. Two field isolates and two reference strains were selected for this study These isolates originated from three different habitats (building material, animal feed, and foodstuff). We have identified media that support or prevent the production of the analyzed mycotoxins
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