Temperature effects on pathogen inactivation in stream water and sediment

Abstract

Pathogen contamination in stream water is a serious concern, which can pose risks to public and animal health, and reducing the risks of pathogens requires enhanced knowledge of pathogen sources and pathogen survival under various environmental and controlled conditions. One of the major factors, which affect pathogen survival, is temperature. To improve existing understanding of pathogen inactivation in stream water and sediment at various temperature conditions, we executed a series of microcosm studies in batch mode for assessing pathogen survival. Water and sediment samples from stream water column and bed sediment of Merced River Watershed, California were collected, and stored at 4°C prior to experiments. Subsequently, heat shock experiments were conducted under temperature controlled conditions. Initial pathogen levels in water and sediment samples were controlled by mixing the inoculum of E. coli, Salmonella, and Listeria, which are water and foodborne pathogens, known for causing illnesses in humans. We studied pathogen survival at 30°C, and 50°C. Results showed that the temperature of heat shock and incubation time under heat shock played crucial role in reducing pathogen levels. Low temperature (30°C) heat shocks and limited time heat shocks with relatively higher temperature (50°C) may not have considerable impacts in reducing pathogen levels.