Fungal contaminants in Turkish bottled water and their mycotoxin-producing potential

The chemical composition and microbial contaminants of commercially bottled water are managed according to public health regulations, but there are gaps in these criteria for fungal agents. For this reason, commercial bottled water brands filled in 19-L polycarbonate bottles from various water sources in western Anatolia and sold in Izmir and neighboring provinces were randomly selected and analyzed.

Fungal screening was carried out in water samples using the membrane filtration technique. The number of fungi was counted in colony-forming units (cfu)/100 ml. All fungi isolated from packaged water samples were initially phenotypically analyzed for initial preliminary identification. Amplification of the well-conserved internal transcribed spacer (ITS) region was performed by polymerase chain reaction (PCR) using internal transcribed spacer (ITS)1/ITS4 primers for genotypic identification of the isolates. Using the basic local alignment search tool (BLAST), sequencing results were compared with the National Center for Biotechnology Information (NCBI) database, and species assignments were made for 31 samples. 25 moulds and 6 yeasts were identified, and molecular identification was supported by the actin gene region. The mycotoxin formation potential of the isolated Penicillium, Aspergillus, Alternaria and Cladosporium spp. was also screened using the ammonium vapor test, LC-MS and HPLC. The amount of citrinin, the metabolite produced by the Penicillium citrinum B4 strain, was determined by liquid chromatography-mass spectrometry.

The most dominant strains detected in the analysis of water samples were Cladosporium, Penicillium and Alternaria. With 411.586 µg/l, the amount of citrinin was well above the upper limit for beverages.

The values obtained here emphasize that fungal contaminants and mycotoxins in bottled water should be included in the water analysis criteria. To the best of our knowledge, this is the first detailed research in this field in Turkey.