Characterization of fungi in office dust: comparing results of microbial secondary metabolites fungal ITS region sequencing viable culture and other microbial indices

摘要

Recent developments in molecular and chemical methods have enabled the analysis of fungal DNA and secondary metabolites, often produced during fungal growth, in environmental samples. We compared three fungal analytical methods by analyzing floor dust samples collected from an office building for fungi using viable culture, internal transcribed spacer (ITS) sequencing, and secondary metabolites using liquid chromatography-tandem mass spectrometry. Of the 32 metabolites identified, 29 had a potential link to fungi with levels ranging from 0.04 (minimum for alternariol monomethylether) to 5,700 ng/g (maximum for neoechinulin A). The number of fungal metabolites quantified per sample ranged from eight to sixteen (average=13/sample). We identified 216 fungal operational taxonomic units (OTUs) with the number per sample ranging from six to twenty-nine (average=18/sample). We identified 37 fungal species using culture and the number per sample ranged from two to thirteen (average=eight/sample). Agreement in identification between ITS sequencing and culturing was weak (kappa=−0.12–0.27). The number of cultured fungal species poorly correlated with OTUs, which did not correlate with the number of metabolites. These suggest that using multiple measurement methods may provide an improved understanding of fungal exposures in indoor environments and that secondary metabolites may be considered as an additional source of exposure.