Photoeradication of Aquatic Pathogens by Curcumin

Waterborn pathogens are eradiated by antimicrobial phototherapy using faint blue light and a natural photosensitizer. • Pathogen eradication by a natural photosensitizer. • Singlet oxygen generation by photoactivated curcumin. • Photochemistry and natural products approaching the SDG goals. • Photodynamic antimicrobial activity. • Antimicrobial mechanism. Photochemistry becomes the basis of the sustainable development goals (SDG) 6 and 7 for clean water and energy. Removing aquatic pathogens is a global requirement to protect humans and aquatic animals from infectious diseases and emerging antibiotic resistance. Photodynamic antimicrobial chemotherapy (PACT) combining photosensitizers and light sources is a greener approach for fighting such pathogens. A photosensitizer drug in PACT produces reactive oxygen species (ROS), rapidly disinfecting its local environment. Here, the ROS reacts with and disrupts the cell walls of the pathogens, apparent from singlet oxygen assays, superoxide assays, spectroscopic analyses, cell viability assays, and scanning electron microscopy imaging. The current study demonstrates disinfection of the aquatic pathogens Vibrio (V.) cholerae , V. harveyi , and V . campbellii by applying curcumin, a natural antioxidant in foods, and light. Photoactivation of curcumin enhances ROS production and enables V. cholerae and V. harveyi disinfection within minutes at submicromolar concentrations. V. campbellii shows higher resistance to curcumin than V. cholerae or V. harveyi , which is due to the low affinity of the cell wall of the former for curcumin. The current study demonstrating curcumin’s antimicrobial activity proposes its potential for water purification and its significance to the SDG goal 6.