University of Helsinki, Department of Applied Chemistry and Microbiology, Division of Microbiology,University of Helsinki, Finland Email: joanna.peltola@helsinki.fi

We showed toxic substances in and isolated toxin producing microbes from water-damaged building materials. The toxins were extracted from the building materials and microbial cultures in methanol and analysed using boar spermatozoa as test cells. The fungal genera isolated from the toxic materials were identified as representatives of Stachybotrys chartarum, Aspergillus, Alternaria, and Penicillium. We found that toxin from the building materials and from four fungal isolates paralysed sperm cell motility and damaged cell membrane at low concentrations (EC50 < 10 mg of methanol soluble solids ml-1 of extended boar semen). The toxic isolates were identified to Stachybotrys chartarum. The toxin from one Stachybotrys chartarum strain was partially purified. To our knowledge, this is the first demonstration of membrane damaging toxin and their producer fungi from the building material.