According to Dr. Kumar, sunlight affects microorganisms that are present in the environment, including foodborne pathogens capable of causing human illnesses. Sunlight can be used as a cost-effective and environmentally responsible way of reducing bacterial counts in agricultural water, given that high levels of light affect bacteria. Determining how to leverage sunlight as an antimicrobial tool could help industry to mitigate the contamination of leafy greens and vegetables by pathogens found in irrigation water.

The UGA team researched how factors such as sunlight, water temperature, and ultraviolet (UV) radiation levels affect Salmonella and E. coli by conducting experiments in real-world conditions with bacteria in the field.

After collecting data, the researchers performed a correlation analysis using artificial neural network modeling to predict the most likely outcomes of various scenarios. The model determined that bacterial populations, when exposed to sunlight, decline more in cooler water than in warmer water. The observation could help scientists understand why bacterial counts tend to be higher in water during the summer months.

Dr. Kumar theorizes that free radicals are more stable in cold water than warm water. In the winter, the sunlight causes the accumulation of more reactive oxygen species (ROS) in the water, but in the summer, there is less ROS in the water. Therefore, sunlight in the winter months might be more antimicrobial than sunlight in the summer months, and that could be why bacteria levels are higher in water during the summer.