|EPPS, SHARVON - Texas A&M University|
|PETRUJKIC, BRANKO - University Of Belgrade|
|SEDEJ, IVANA - University Of Novi Sad|
|KRUEGER, NATHAN - Blinn College|
|PHILLIPS, TIMOTHY - Texas A&M University|
Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2014
Publication Date: 10/13/2014
Publication URL: http://handle.nal.usda.gov/10113/59711
Citation: Epps, S.V., Petrujkic, B.T., Sedej, I., Krueger, N.A., Harvey, R.B., Beier, R.C., Stanton, T.B., Phillips, T.D., Anderson, R.C., Nisbet, D.J. 2014. Inhibition of Campylobacter by free thymol liberated from thymol-ß-D-glucopyranoside by ß-glycoside-hydrolyzing gut bacteria. Food Chemistry. 173:92-98.
Interpretive Summary: Campylobacter are important bacteria that cause foodborne illness in humans. These foodborne pathogens colonize the gut of poultry, pigs, and cattle and can contaminate meat and milk. Thymol is a natural plant product that reduces the survivability of Campylobacter in the laboratory but is not very effective when fed to animals because it is rapidly absorbed in the stomach which precludes its delivery to the cecum and large intestine where Campylobacter primarily reside. In a previous study, we hypothesized and subsequently demonstrated that if we linked thymol to a common sugar compound, such as glucose, using a special chemical bond called a beta-glycosidic bond, it would be more resistant to absorption and degradation in the stomach. This hypothesis is based on the understanding that many beta-glycosidic bonds are resistant to degradation and absorption because higher animals lack the enzymes needed to break it down. Conversely, many bacteria in their cecum and large intestine are known to possess the needed enzyme and thus would be expected to be able to liberate thymol, thereby allowing it to be active against Campylobacter at these sites. While our previous study confirmed that the new chemical, thymol-beta-D-glucopyranoside, was resistant to absorption, we conducted this study to see if it would kill Campylobacter. We found that thymol-beta-D-glucopyranoside was able to kill Campylobacter, causing more than a 1000-fold decrease in its survivability, but as expected, this anti-Campylobacter activity required the presence of other cecal and large intestinal bacteria able to liberate the thymol. These results provide support for our original hypothesis that thymol-beta-D-glucopyranoside or similar beta-glycosides may be suitable candidates to be fed to food animals to reduce their carriage of Campylobacter. Ultimately, this research may lead to the development of new, non-antibiotic interventions to help farmers continue to produce safe and wholesome meat and milk for the American consumer.
Technical Abstract: Campylobacter are a leading cause of bacterial-derived foodborne illness. Thymol is a natural product that reduces survivability of Campylobacter in vitro, but results from animal studies indicate that absorption within the proximal alimentary tract precludes its delivery to the cecum and large intestine. We compared the anti-Campylobacter activity of thymol against that of thymol-ß-D-glucopyranoside, the latter resistant to absorption. When treated with 1 mM thymol, C. coli and jejuni were reduced >3.41 log10 cfu/mL after 48 h in either pure or co-culture with a ß-glycoside-hydrolyzing Parabacteroides distasonis. Campylobacter coli and jejuni were not reduced during pure culture with 1 mM thymol-ß-D-glucopyranoside but were reduced >3.72 log10 cfu/mL during co-culture with P. distasonis. After 24 h incubation with porcine or bovine fecal microbes possessing endogenous ß-glycoside-hydrolyzing activity, C. coli and C. jejuni were reduced >2.50 log10 cfu/mL whether treated with 1 mM thymol or thymol-ß-D-glucopyranoside. Volatile fatty acid production was reduced by thymol-ß-D-glucopyranoside treatment indicating the conjugate-inhibited fermentation which may limit its application to the last few meals before harvest. These results suggest that thymol-ß-D-glucopyranoside or similar ß-glycosides may be suitable candidates to escape absorption within the proximal gut and become activated by bacterial ß-glycosidases in the distal gut.