By Jamie Martin
Scientists have completed a major environmental research project designed to better understand how harmful bacteria move through agricultural landscapes. The five-year study focused on California’s Central Coast, a major produce growing region known for supplying a large portion of the country’s leafy greens.
The research was led by federal food safety officials in partnership with the Western Center for Food Safety at the University of California, Davis. The project began in 2020 after several foodborne illness outbreaks raised concerns about how disease-causing bacteria enter produce production areas.
“This was a five-year collaborative effort to test the environment within and surrounding produce fields, such as soil, surface water, sediment and air,” said Rob Atwill, a principal investigator for the Western Center for Food Safety and epidemiologist with the UC Davis Weill School of Veterinary Medicine. “We could not have done this without our partnership with the California livestock and produce industries.”
Researchers worked with growers, ranchers, landowners, and government agencies to collect environmental samples from across the region. The team examined soil, air, water, and sediment found around produce fields to understand how bacteria travel and survive in the environment.
Scientists also collected fecal samples from both livestock and wildlife at ranches and vineyards. Animals studied included cattle, deer, feral pigs, coyotes, bobcats, birds, and insects. These samples helped researchers identify how bacteria may move between animals, water, and farmland.
The early results show that harmful strains of E. coli exist in many environmental sources across the region. The bacteria were most often found in animal waste and in surface water such as rivers and creeks. Researchers also detected the bacteria in sediments and occasionally in irrigation runoff.
Farm soil showed lower levels of bacteria overall, although higher levels were observed near waterways and areas close to cattle ranches. This suggests that water systems may play an important role in helping bacteria move across landscapes.
While several strains of E. coli O157:H7 were detected, scientists did not find the same strain linked to outbreaks between 2016 and 2020. Some illnesses causing strains were observed in the environment for up to two years.
“The agricultural industry has made a lot of changes in the last decade to address food safety issues and our data support that they are focused on the right things,” said Linda J. Harris, co-principal investigator with the Western Center for Food Safety and professor emerita in the UC Davis Food Science and Technology department.
“These data will be used by the industry to inform future targeted research and refinements, if needed, to provide existing guidance on best practices for growers to reduce food safety risks,” said Harris.
Researchers say the findings confirm that harmful bacteria naturally exist in agricultural environments. The information collected will help guide future research and support improved food safety practices for produce growers across the industry.
Photo Credit: gettyimages-anna-tarazevich
Categories: National