New Listeria Species Discovered
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New Listeria Species Discovered: What Does This Mean For Food Safety?

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A new species of Listeria has been discovered by Scientists from Cornell University. Five previously unknown species of Listeria have been added to the list. The most infamous of the genus you may recognise; Listeria monocytogenes, an opportunistic pathogen that causes listeriosis. A food-borne illness affecting several processed foods.

Where was the new Listeria species discovered?

While examining the prevalence of listeria in agricultural soil throughout the U.S., Cornell food scientists have stumbled upon five previously unknown and novel relatives of the bacteria, according to new research published May 17 in the International Journal of Systematic and Evolutionary Microbiology.

The discovery, researchers said, will help food facilities identify potential growth niches that until now, may have been overlooked – thus improving food safety.

Listeria are notoriously difficult to remove from the food factory. They are persistent, able to resist chemical treatment and grow is difficult to reach areas, whilst being able to grow well as refrigeration temperatures.

“This research increases the set of listeria species monitored in food production environments,” said lead author Catharine R. Carlin, a doctoral student in food science. “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.”

What makes the new species unique?

One of the novel species, L. immobilis, lacked motility, or the ability to move.  Listeria move a lot. Among scientists, motility was thought to be common among listeria closely related to L. monocytogenes, a well-known food-borne pathogen – and used as a key test in listeria detection methods. This discovery effectively calls for a rewrite of the standard identification protocols issued by food safety regulators, Carlin said.

“This paper describes some unique characteristics of listeria species that are closely related to Listeria monocytogenes, which will be important from an evolutionary perspective and from a practical standpoint for the food industry,” said co-author Martin Wiedmann, Ph.D. ’97, the Gellert Family Professor in Food Safety and Food Science. “Likely, some tests will need to be re-evaluated.”

After naming L. immobilis to reflect this organism’s non-motile characteristic, three of the other species were named to honor other listeria researchers:

  • L. cossartiae for Pascale Cossart, a bacteriologist at the Pasteur Institute of Paris;
  • L. farberi for Jeff Farber, a microbiologist at the at the University of Guelph, Canada; and
  • L. portnoyii for Daniel Portnoy, a microbiologist at the University of California, Berkeley.

The species L. rustica was taken from the Latin word “rusticus” and signifies its rural origin. 

The research further supports the need to separate testing of Listeria species from the specific detection of Listeria monocytogenes.

The new study was published in the International Journal of Systematic and Evolutionary Microbiology.

Source: Cornell University

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