LAUSR

ABSTRACT Most of the studies about the groundwater quality have been focused on chemical and bacterial contamination. However, fungal contamination of drinking water has been suggested as an underestimated problem. We studied 20 wells in the Arabian Peninsula, identified their fungal contamination and assessed the potential harmfulness of the fungi to humans. We identified 28 fungal species, many of them commonly known to occur in drinking water. To assess the potential role of fungi in water, we selected 15 species for a bioassay with a model bacterium Bacillus subtilis. All fungal species inhibited the growth of B. subtilis, thus showing antibacterial activity. These fungi were interpreted to secrete toxins and thus, be possibly harmful to humans. Nine of the species retained their antibacterial activity in a boiling treatment. Therefore, they cannot be disinfected by boiling. This study raises new aspects and questions about the harmfulness of the fungal contamination in drinking water to humans.