Food scientists create national atlas for deadly listeria

Date:
August 11, 2021
Source:
Cornell University
Summary:
Among the deadliest of foodborne pathogens, Listeria monocytogenes
soon may become easier to track down in food recalls and other
investigations, thanks to a new genomic and geological mapping
tool created by food scientists.



FULL STORY ========================================================================== Among the deadliest of foodborne pathogens, Listeria monocytogenessoon
may become easier to track down in food recalls and other investigations, thanks to a new genomic and geological mapping tool created by Cornell University food scientists.


==========================================================================
The national atlas will tell scientists where listeria and other related species reside within the contiguous United States, which could help
them trace and pinpoint sources of listeria found in ingredients, food processing facilities and finished products, according to research
published July 15 in Nature Microbiology.

"As we're trying to figure out the risk of getting listeria from soil and different locations, our group created a more systematic way of assessing
how frequently different listeria are found in different locations," said senior author Martin Wiedmann, food safety and food science professor in
the College of Agriculture and Life Sciences. "We've studied listeriain
places as diverse as New York, Colorado and California, but before
this atlas, [it] was difficult to make comparisons and assess listeria diversity in different locations." Listeria mononcytogenes in foods can
make people extremely sick. The Centers for Disease Control and Prevention (CDC) estimate that each year 1,600 people in the U.S. get listeriosis;
of those, about 260 die.

Knowing that listeria occurs naturally in soil, the Cornell group asked hundreds of other scientists across the country to scoop up soil samples
from generally undisturbed places in the natural world, such as the
off-trail areas of state and national parks.

From these samples, the group developed a nationwide atlas of 1,854
listeria isolates, representing 594 strains and 12 families of the
bacteria called phylogroups.

Lead author Jingqiu Liao, who worked in Wiedmann's laboratory as
a graduate student, is now a post-doctoral researcher at Columbia
University. She had supplemented the research by acquiring soil samples
in her own travels and found listeriapresent across a wide range of environmental circumstances. This bacterium is controlled mainly by
soil moisture, salinity concentrations and molybdenum -- a trace mineral
found in milk, cheese, grains, legumes, leafy vegetables and organ meats.

"The goal of this work was to systematically collect soil samples across
the United States," said Liao, "and to capture the true large-scale
spatial distribution, genomic diversity and population structure of
listeria species in the natural environment.

"With whole genome sequencing and comprehensive population genomics
analyses," Liao said, "we provided answers to the ecological and
evolutionary drivers of bacterial genome flexibility -- an important
open question in the field of microbiology." Liao explained that this
work can serve as a reference for future population genomics studies and
will likely benefit the food industry by locating listeria contaminations
that may have a natural origin.

If listeria is found in a processing facility in the western U.S., for
example, and that facility had used ingredients from a distant state,
Wiedmann said, "knowing the genomic information of listeriaisolates
and their possible locations across the U.S., we can better narrow
the origins to a specific region. You can use this information almost
like a traceback. It's not always proof, but it leads you to evidence."
The research was funded by the Center for Produce Safety in Woodland, California.

========================================================================== Story Source: Materials provided by Cornell_University. Original written
by Blaine Friedlander. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jingqiu Liao, Xiaodong Guo, Daniel L. Weller, Shaul Pollak,
Daniel H.

Buckley, Martin Wiedmann, Otto X. Cordero. Nationwide genomic
atlas of soil-dwelling Listeria reveals effects of selection and
population ecology on pangenome evolution. Nature Microbiology,
2021; 6 (8): 1021 DOI: 10.1038/s41564-021-00935-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210811162839.htm

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