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Toxigenic Microbes in Indoor Environment: Identification, Structure and Biological Effects of the Aerosolizing Toxins
Salkinoja-Salonen M.S., Ph.D., Andersson M.A., M.Sc, Mikkola R., M.Sc, Paananen A.,B.Sc, Peltola J., M. Agr. & For., Mussalo-Rauhamaa M.D.,Ph.D., Saris N Ph.D., Grigorjev Ph.D, Helin Ph.D., Koljalg, Ph.D, Timonen M.D.,Email: mirja.salkinoja-salonen@helsinki.fi

Almost 500 pure cultures, bacteria and fungi, were isolated and identified to genus or species level from indoor environments where the occupants were suffering health problems. Over 80 different taxa were identified. Seven bacterial species classified to Hazard Group 2 were found. Extracts prepared from the building materials and from the pure cultures, were tested for their effects on cellular energy production and conservation using boar spermatozoon and human NK cells as test cells. Strains giving toxic responses were found among strains from 11 taxa. Cell free extracts prepared from cultures of Bacillus cereus, Bacillus licheniformis, Streptomyces griseus, a new species of Nocardiopsis, Stachybotrys chartarum and Trichoderma sp were shown to contain toxins that depleted the spermatozoon of ATP and destroyed plasma membrane integrity. Strains of Streptomyces griseus and Bacillus cereus were shown to produce toxins that caused mitochondrial swelling and programmed NK-cells towards apoptosis. These toxins were dodecadepsipeptides and operated as K+ ionophores across the mitochondrial membrane. Strains of Bacillus licheniformis and Trichoderma produced toxins that depleted the spermatozoon of ATP. The toxins were nonenzymatic, highly hydrophobic, robust molecules of small size (<104 g mol-1), effective at low concentration (ppb). We propose that the building related health symptoms of the occupants exposed to one or several of the taxa indicated above, may be caused by microbially emitted toxins. We discuss possible mechanisms of human toxicity.