Location: Food and Feed Safety ResearchTitle: Bactericidal effect of hydrolysable and condensed tannin extracts on Campylobacter jejuni in vitro Author
|Nisbet, David - Dave|
Submitted to: Folia Microbiologica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2012
Publication Date: 4/20/2012
Publication URL: http://handle.nal.usda.gov/10113/57224
Citation: Anderson, R.C., Vodovnik, M., Min, B.R., Pinchak, W.E., Krueger, N.A., Harvey, R.B., Nisbet, D.J. 2012. Bactericidal effect of hydrolysable and condensed tannin extracts on Campylobacter jejuni in vitro. Folia Microbiologica. 57:253-258. Interpretive Summary: Campylobacter is a leading bacterial cause of human foodborne illness worldwide, and strategies are sought to reduce intestinal colonization of food-producing animals by this important pathogen. In this study, we tested the antimicrobial activity of several naturally occurring plant compounds called tannins. Sample tannins were extracted from blackberries, cranberries, chestnuts (hydrolysable tannin), and from plants called mimosa, quebracho, and sorghum (condensed tannins). When tested via a common microbiological method known as a disc diffusion assay, we found that all tannins (added at 100 mg/mL) inhibited the growth of Campylobacter, but inhibition by the condensed tannin was less. When tested in broth culture, simple tannins inhibited growth of Campylobacter more than the condensed tannins, but not the hydrolysable tannin-rich chestnut extracts. These results demonstrate the antimicrobial activity of various tannins against Campylobacter and reveal that simple condensed tannins may be less efficient than complex hydrolysable tannins in controlling Campylobacter in gut environments. Ultimately, this research will provide important information to help food producers and processors learn how to more effectively control Campylobacter so they can continue to provide safe food products for the American consumer.
Technical Abstract: Strategies are sought to reduce intestinal colonization of food-producing animals by Campylobacter jejuni, a leading bacterial cause of human foodborne illness worldwide. Presently, we tested the antimicrobial activity of hydrolysable-rich blackberry, cranberry, chestnut tannin extracts, and condensed tannin-rich mimosa, quebracho, and sorghum tannins (each at 100 mg/mL) against Camplyobacter jejuni via disc diffusion assay in the presence of supplemental casamino acids. We found that when compared to non-tannin-treated controls, all tested tannins inhibited the growth of C. jejuni and that inhibition by the condensed tannin-rich mimosa and quebracho extracts was mitigated in nutrient-limited medium supplemented with casamino acids. When tested in broth culture, both chestnut and mimosa extracts inhibited growth of C. jejuni. This inhibition was much greater in nutrient-limited than in full-strength medium. Consistent with observations from the disc diffusion assay, the inhibitory activity of the condensed tannin-rich mimosa extracts, but not the hydrolysable tannin-rich chestnut extracts, was mitigated by casamino acid supplementation to the nutrient-limited medium, likely because the added amino acids saturated the binding potential of the condensed tannins. These results demonstrate the antimicrobial activity of various hydrolysable and condensed-tannin rich extracts against C. jejuni and reveal that condensed tannins may be less efficient than hydrolysable tannins in controlling C. jejuni in gut environments containing high concentrations of amino acids and soluble proteins.