Sunlight-Activated Propidium Monoazide Pretreatment for Differentiation of Viable and Dead Bacteria by Quantitative Real-Time Polymerase Chain Reaction

Polymerase chain reaction (PCR)-based methods have been developed and increasingly used for rapid and sensitive detection of pathogens in water samples to better protect public health. A propidium monoazide (PMA) pretreatment can help to differentiate between viable and dead cells, but the photoactivation of PMA normally requires the use of an energy-consuming halogen light, which is not suitable for off-the-grid applications. Herein, we investigate sunlight as an alternative light source. Our results suggest that sunlight can successfully activate PMA, and the sunlight-activated PMA pretreatment can effectively reduce the amplification of DNA derived from dead cells in PCR assays. Potentially, a sunlight-activated PMA pretreatment unit can be integrated into a lab-on-a-chip PCR device for off-the-grid microbial detection and quantification.