The Role of Reactive Oxygen Species in the Solar Disinfection (SODIS) System of water contaminated with Escherichia coli and Salmonella enterica serovar Typhimurium

Solar disinfection (SODIS) is a technique that uses solar radiation and heat to inactivate microbial activity to the point where the water is safe for human consumption. Studies have confirmed that oxygen plays a critical role in solar disinfection and it is thought that ultraviolet-A (UV-A) radiation from sunlight induces the formation of reactive oxygen species (ROS) from dissolved organic carbon and oxygen. This study investigated the possibility that the UV-A bactericidal effects are due to photo-inactivation via the production of ROS. Escherichia coli B23 and Salmonella enterica serovar Typhimurium LT2 were subjected to UV-A irradiation and hydrogen peroxide levels, which are indicative of ROS generation and were measured using a fluorometric assay. A decline in viable bacteria was observed following UV-A exposure for all cell strains. The H O 2 2 detection assay yielded inconclusive results.