Institute of Agriculture and Natural Resources
USDA Grant Supports New E. coli Research By Daniel R. Moser University of Nebraska–Lincoln scientists are taking their battle against foodborne pathogens such as E. coli O157:H7 into the belly of the beast, as it were – hoping to figure out what is in the gut of some livestock that makes them so-called “supershedders” of pathogens. The research team, headed by food microbiologist Andy Benson, received a five-year, $2.35 million grant from the U.S. Depart-
The goal is to try to associate organisms in the cattle’s gastrointestinal tract with genes in the animals to see if some of those interactions are causing certain animals to become supershedders of the E. coli pathogen, while others that may have E. coli present do not shed it in unusual numbers. If those relationships can be understood, it may be possible to develop breeding and genetic programs to reduce the number of animals that shed high levels of E. coli O157:H7, salmonella, campylobacter and other pathogens.
ment of Agriculture last summer. The project will build on earlier work done with lab mice by Benson and his collaborators. E. coli O157:H7 long has been known to colonize the bovine
UNL scientists will do so in partnership with USDA’s Meat Animal Research Center at Clay Center and Geneseek, a private, Lincoln-based company that specializes in genotyping. “It’s really a Nebraska-centric project,” Benson said, noting that all of the important pieces to the research exist in the state. The goal is to try to associate organisms in the cattle’s gastro-
gut. Although it causes no disease symptoms in the animals, it can
intestinal tract with genes in the animals to see if some of those
be transmitted to humans through improperly cooked beef, among
interactions are causing certain animals to become supershedders of
other ways.
the E. coli pathogen, while others that may have E. coli present do
Pre-harvest E. coli research has focused primarily on the
not shed it in unusual numbers.
epidemiology of the disease, along with field-level and management
If those relationships can be understood, it may be possible
factors that affect transmission from animal to animal, Benson said.
to develop breeding and genetic programs to reduce the number
“More recently, studies looking at animal-level factors have
of animals that shed high levels of E. coli O157:H7, salmonella,
shown that while many animals may be carriers of the organism, a small portion of animals shedding the organism at very high levels
campylobacter and other pathogens. “While epidemiologically oriented approaches have provided
may account for much of the transmission risk,” added Benson, the
extensive information about the transmission patterns of the organ-
W. W. Marshall Professor of Biotechnology in UNL’s Department
ism, they have essentially failed to come up with meaningful and
of Food Science and Technology.
effective pre-harvest interventions that work in beef production,”
Those animals are referred to as “supershedders.”
Benson said. “On the other hand, breeding strategies, which have
E. coli research so far has yielded disease-fighting interventions
heretofore never been considered as an approach, could be imple-
primarily at slaughter and post-slaughter stages of production, Ben-
mented as a relatively simple intervention with potentially huge
son said. With the newly funded research, scientists hope to devise
payoffs, ultimately reducing numbers of ‘supershedders’ that are
some intervention strategies against the disease much earlier in the
released into feeding operations.”
production process. Previous research at UNL by a large team led by Benson used mice to show that genetic makeup of vertebrate hosts is a key factor
Benson said producers would be eager for such a breakthrough. “Many producers are already using sophisticated approaches to
in controlling the levels of individual organisms within the entire
manage their breeding programs. For them, it would be yet another
microbiota carried in the gut. This work, funded by the National
gene and another trait on their list of things that want to breed for
Institutes of Health, combines quantitative genetics and micro-
or breed against,” he said.
biota analysis across different mouse populations. Collaborators in
MARC will provide about 1,500 animals for the research, and
this research include Stephen Kachman, a UNL statistics scientist;
its bovine gene mapping group, including Larry Keuhn and War-
Etsuko Moriyama, a UNL genomics and bioinformatics scientist;
ren Snelling, will be involved, as will USDA microbiologists Jim
and Daniel Pomp, a mouse geneticist formerly of UNL and now of
Wells and Jim Bono. Geneseek will handle the genotypic studies.
the University of North Carolina. Benson said the team’s research has documented a strong association of several gut organisms with 13 different genetic loca-
UNL’s Gut Function Initiative and Core for Applied Genomics and Ecology also will be involved in the research. Benson said the MARC-UNL partnership was “greatly facili-
tions in the mouse, with more still being discovered as the work
tated” by John Pollak, director of MARC, and Rolando Flores,
progresses.
head of UNL’s Department of Food Science and Technology.
“It wasn’t a big leap to think, ‘you know, this hasn’t really been looked at in food animals,’” Benson said. The new USDA grant 18 | GoodNUz | IANR
will enable Benson and other scientists to do just that.
The USDA grant was part of the Food Safety Foundational Awards from the National Institute of Food and Agriculture.