A Michigan State University researcher is working to characterize the physiological changes that occur in Shiga toxin-producing Escherichia coli O157:H7 (STEC) bacteria that is present on romaine lettuce during postharvest cooling and refrigerated transport to processors, which could affect the pathogen’s virulence and detectability characteristics. The end goal of the research, which is being funded by the Center for Produce Safety, is to develop an easily accessible online tool for industry that identifies practices to mitigate the risks of STEC transmission via romaine lettuce.
While several researchers have examined STEC on romaine lettuce in the field and during postharvest washing at processors, little is known about potential changes in the microorganism’s physiology during postharvest cooling and refrigerated transport to processors. Compared to the growing season and processing, the time romaine spends in coolers and refrigerated transport after harvest is relatively small. However, knowledge about what happens during the short period of time would be valuable information for industry.