| Viral foodborne outbreaks are a serious threat to public health and fresh produce is becoming increasingly recognized as a transmission vehicle. Potential pre- and post-harvest sources of contamination include irrigation and processing water, soil, manure, equipment, and human handling. Traditional detection methods limit studies on viruses in produce. New culture-independent metagenomic next generation sequencing (NGS) technologies present an opportunity for generating an improved understanding of the virus communities (virome) associated with foods. The goals of this study were to use NGS technology for the first time to identify the virome present in irrigation water and lettuce in the field and to investigate the efficacy of current post-harvest leafy green processing and disinfection practices during a contamination event. In this study, most viruses found in irrigation water and lettuce from the field environment could not be identified suggesting limited knowledge of the virome in these environments. Human enteric viruses such as rotavirus A and picobirnavirus were identified in field lettuce. On the processing side, the efficacy of a chlorine-based sanitizer against MS2 coliphage on fresh-cut romaine lettuce was assessed during simulated commercial production of fresh-cut lettuce. Flume washing lettuce in 25 ppm of free chlorine did not significantly reduce viral levels on romaine lettuce when compared to water without chlorine. Overall, this study suggests that metagenomic technology can be used as a potential tool for monitoring food safety. Viruses were present in field lettuce and resistant to current commercial chlorine disinfection techniques, posing a possible threat to public health. |
