Capacity of the bovine intestinal mucus and its components to support Escherichia coli O157:H7 growth
Kansas Agricultural Experiment Station Research Reports
C. Aperce
J. Heidenreich
James S. Drouillard
Follow this and additional works at: https://newprairiepress.org/kaesrr Part of the Other Animal Sciences Commons Recommended Citation Aperce, C.; Heidenreich, J.; and Drouillard, James S. (2010) "Capacity of the bovine intestinal mucus and its components to support Escherichia coli O157:H7 growth," Kansas Agricultural Experiment Station Research Reports: Vol. 0: Iss. 1. https://doi.org/10.4148/2378-5977.2839
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Capacity of the bovine intestinal mucus and its components to support
Escherichia coli O157:H7 growth
Abstract
Escherichia coli O157:H7 contamination of human food products is a major concern for the beef industry.
The pathogens responsible for outbreaks often originate from cattle, and E. coli O157:H7 can thrive in
healthy cattle. To control contamination in the food chain, it is essential to understand how this pathogen
is able to grow and compete with other bacteria in the gastrointestinal tracts of cattle. Previous studies
have shown that bovine intestinal mucus supports bacterial colonization and can selectively influence
makeup of the bacterial population. Intestinal mucus is made of mucins, which are gel-forming
glycoproteins. Mucin molecules contain sialic acid that must be removed by neuraminidase enzyme to
allow for complete degradation of mucin. E. coli O157:H7 lacks neuraminidase and should have little
ability to degrade the complex mucin molecules. Our objective was to evaluate bovine intestinal mucus
and its components in terms of their capacity to support E. coli O157:H7 growth in the presence or
absence of feces and to understand the roles various enzymes play in this process.
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Capacity of the Bovine Intestinal Mucus and
Its Components to Support Escherichia coli
O157:H7 Growth1
Introduction
Escherichia coli O157:H7 contamination of human food products is a major concern
for the beef industry. Thepathogens responsible for outbreaks often originate from
cattle, and E. coli O157:H7 can thrive in healthy cattle. To control contamination
in the food chain, it is essential to understand how this pathogen is able to grow and
compete with other bacteria in the gastrointestinal tracts of cattle.
Previous studies have shown that bovine intestinal mucus supports bacterial
colonization and can selectively influence makeup of the bacterial population. Intestinal mucus
is made of mucins, which are gel-forming glycoproteins. Mucin molecules contain sialic
acid that must be removed by neuraminidase enzyme to allow for complete degradation
of mucin. E. coli O157:H7 lacks neuraminidase and should have little ability to degrade
the complex mucin molecules. Our objective was to evaluate bovine intestinal mucus
and its components in terms of their capacity to support E. coli O157:H7 growth in
the presence or absence of feces and to understand the roles various enzymes play in
this process.
Experimental Procedures
Intestinal tissues from freshly harvested cattle were collected and transported to our
laboratory in chilled saline. Sections of the ileum and colon were washed with buffer
solution, and mucus was harvested by gently scraping the epithelium. We prepared a
mix of five selected strains of Shiga toxin-producing E. coli O157:H7 resistant to
nalidixic acid (NalR) and added the mix to a buffer or a similar amount of fecal inoculums
collected from the rectum of a steer fed a high-grain diet.
Subsequently, we added harvested intestinal mucus or individual mucus components
to the culture to assess which components were most capable of supporting NalR E. coli
O157:H7 growth. Intestinal mucus was added at a concentration of 10 mg/mL. Single
components of mucus (galactose, D-galacturonic acid, D-gluconic acid, D-glucuronic
acid, mannose, L-alpha-phosphatidylserine, sialic acid, and N-acetyl-D-glucosamine)
were added at the same concentration, except for L-alpha-phosphatidylserine, which
was added at 1 mg/mL. Initial concentrations of E. coli O157:H7 and fecal bacteria in
the cultures (...truncated)