Occurrence of biofilm forming fungal species and in vitro evaluation of anti-biofilm activity of disinfectants used in drinking water

Fungal contamination in drinking water has garnered considerable attention over the past few decades, especially considering the detrimental consequences of pathogenic fungal species on both human and animal health. The formation of biofilms by certain species is a considerable factor contributing to the emergence of severe fungal infections. This research was designed to isolate and identify fungi, particularly those capable of forming biofilms from 150 samples of drinking water sourced from various locations. The isolated fungal species were tested for them in vitro biofilm formation using a microtitration plate method and the crystal violet assay was applied to quantify the established biofilms. The effectiveness of three disinfectants, namely ozone, chlorine, and hydrogen peroxide, in preventing the formation of biofilms by the most isolated fungal species was monitored. The findings indicated that Aspergillus species were the most prevalent in drinking water, comprising 63.33% (95/150) of the total number of fungal species identified. Aspergillus fumigatus and Aspergillus flavus were identified as the primary contributors to biofilm formation in drinking water distribution systems with prevalence rates of 41.00 and 34.00%, respectively, among all Aspergillus species. The outcomes of the in vitro studies demonstrated that the ozone disinfectant exhibited promising results in inhibiting fungal biofilms compared to chlorine and hydrogen peroxide. In conclusion, these findings provided valuable insights for water distribution authorities to develop effective regimens for controlling biofilm-forming fungal species using suitable antifungal biofilm disinfectants.