Intracellular mechanisms of solar water disinfection

Abstract

Solar water disinfection (SODIS) is a zero-cost intervention measure to disinfect drinking water in

areas of poor access to improved water sources, used by more than 6 million people in the world. The

bactericidal action of solar radiation in water has been widely proven, nevertheless the causes for this

remain still unclear. Scientific literature points out that generation of reactive oxygen species (ROS)

inside microorganisms promoted by solar light absorption is the main reason. For the first time, this

work reports on the experimental measurement of accumulated intracellular ROS in E. coli during solar

irradiation. For this experimental achievement, a modified protocol based on the fluorescent probe

dichlorodihydrofluorescein diacetate (DCFH-DA), widely used for oxidative stress in eukaryotic cells,

has been tested and validated for E. coli. Our results demonstrate that ROS and their accumulated

oxidative damages at intracellular level are key in solar water disinfection