Case report: contamination of a drinking water distribution system by -dominated biofilm in the Midwestern United States.

Fungal contamination of drinking water distribution systems can impact water quality with implications for public health. We document an instance of spp. biofilm contamination of customer taps in the Midwest United States following consumer complaints. Three samples of black biofilm were collected from customer taps in Ohio and then processed using next-generation DNA sequencing of the bacterial 16S and fungal ITS regions. Two samples with successful ITS sequencing were dominated by spp., putatively identified as and . Dominant bacterial phyla in samples included Proteobacteria, Bacteroidetes, Actinobacteria, and Acidobacteria. Bacterial composition varied substantially at the family and genus levels, and potentially pathogenic bacteria (i.e., spp., spp., spp., and spp.) were detected. The potential for fungal contamination of drinking water distribution systems should be evaluated when biofilms are observed.