Characterization of Stachybotrys from water-damaged buildings based on morphology, growth, and metabolite production

Abstract

Stachybotrys was found to be associated with idiopathic pulmonary hemorrhage in infants in Cleveland, Ohio. Since that time, considerable effort has been put into finding the toxic components responsible for the disease. The name Stachybotrys chartarum has been applied to most of these isolates, but inconsistent toxicity results and taxonomic confusion prompted the present study. In this study, 122 Stachybotrys isolates, mainly from water-damaged buildings, were characterized and identified by combining three different approaches: morphology, colony characteristics, and metabolite production. Two different Stachybotrys taxa, S. chartarum and one undescribed species, were found in water-damaged buildings regardless of whether the buildings were in Denmark, Finland, or the USA. Furthermore, two chemotypes could be distinguished in S. chartarum. One chemotype produced atranones, whereas the other was a macrocyclic trichothecene-producer. The second undescribed taxon produced atranones and could be differentiated from S. chartarum by its growth characteristics and pigment production. Our results correlate with different inflammatory and toxicological properties reported for these same isolates and show that the three taxa/chemotypes should be treated separately. The co-occurrence of these three taxa/chemotypes in water-damaged buildings explains the inconsistent results in the literature concerning toxicity of Stachybotrys isolated from that environment.

• Atranones
• colony diameter
• identification
• macrocyclic trichothecenes
• pigment production
• Stachybotrys chartarum

The authors are very grateful to Dr. J. Peltola, Dr. M. Gareis, Dr. L. Niessen, Dr. P. Parikka, and Dr. A. Hyvärinen for donating fungal isolates and to Dr. P. Skouboe for the RAPD and AFLP analyzes. The authors are also grateful to Dr. J.C. Frisvad for advice on the taxonomy. This study is a part of the Danish research program ‘Mould in buildings’. BBJ wishes to thank the National Bank of Denmark and the Technical University of Denmark for hosting his sabbatical year, 1999–2000. The program is supported by the Danish Government and private companies through the Danish Research Agency.