Cornell University Discovers 5 New Species Within the Listeria Genus
A food science researcher group at Cornell University recently discovered five new species within the listeria genus while studying the prevalence of listeria in agricultural soil throughout the U.S. Their research was published on May 17, 2021, in the International Journal of Systematic and Evolutionary Microbiology. This new discovery is an important accomplishment for the food safety industry because it will provide a deeper understanding of the potential growth niches of the bacteria.
Catherine Carlin, the lead author of the research and a doctoral student in food science said, “this research increases the set of listeria species monitored in food production environments”. Furthermore, Carlin said, “expanding the knowledge base to understand the diversity of listeria will save the commercial food world confusion and errors, as well as prevent contamination, explain false positives and thwart foodborne outbreaks.”
Co-author, Martin Wiedmann, Ph.D. ’97, the Gellert Family Professor in Food Safety and Food Science, said that the discovery of these new listeria species “will be important from an evolutionary perspective and from a practical standpoint for the food industry”.
The discovery was made when the Wiedmann research group took soil samples from across the U.S. and agricultural water samples from New York, within which they detected 27 listeria isolates that could not be identified with any known listeria species. Subsequent Whole Genome Sequence analysis revealed five new and novel clusters.
Carlin explains that one of the five newly discovered species, L. immobilis, is particularly novel in that it lacks motility (movement), which was previously thought to be a common characteristic of any listeria closely related to L. monocytogenes. Consequently, motility has been a standard test for the detection of foodborne pathogenic listeria. Therefore, this new discovery will require the re-development of previous detection and identification protocols in food safety testing.
The second species was named L. rustica, reflecting the rural origin of its discovery. The remaining species were named in honor of the other contributing researchers: L. cossartiae for Pascale Cossart, a bacteriologist at the Pasteur Institute of Paris, L. farberi for Jeff Farber, a microbiologist at the University of Guelph, Canada, and L. portnoyii for Daniel Portnoy, a microbiologist at the University of California, Berkeley.
Since L. monocytogenes, one of the most common pathogenic types of listeria, commonly coexists with other species of listeria, the detection of other species, even non-pathogenic species of listeria, will help in the identification of pathogenic listeria in food safety testing going forward.