Screening of Condensed Tannins from Canadian Prairie Forages for Anti–Escherichia
coli O157:H7 with an Emphasis on Purple Prairie Clover (Dalea
Tannins from forages grown (n = 10) on the Canadian prairie, as well as from Quebracho, Rhus semialata, and brown seaweed (Ascophyllum nodosum), were screened for anti–Escherichia coli O157:H7 activity against E. coli O157:H7 strain 3081 at a
concentration of 400 μg/ml for each tannin type, except for brown seaweed, which was at 50 μg/ml. Growth of the bacteria was assessed by measuring the optical density at 600 nm over 24 h. Tannin from seaweed at a concentration of 50 μg/ml inhibited growth of strain 3081. Among the
terrestrial forages, only condensed tannins (CT) from purple prairie clover (Dalea purpurea Vent; PPC) increased (P < 0.05) the lag time and reduced (P < 0.05) the growth rate of E. coli O157:H7. The anti–E. coli O157:H7 activity of PPC CT was
further assessed by culturing E. coli strain ATCC 25922 and eight strains of E. coli O157:H7 with PPC CT at 0, 25, 50, 100, or 200 μg/ml. Selected strains were enumerated after 0, 6, and 24 h of incubation, and fatty acid composition was determined after 24 h of incubation.
E. coli strain 25922 was cultured with 0, 50, or 200 μg of CT per ml and harvested during the exponential growth phase for examination by transmission electron microscopy. Increasing CT concentration linearly increased (P < 0.001) the lag times of seven strains and linearly
reduced (P < 0.001) the growth rates of eight E. coli O157:H7 strains. Proportions of unsaturated fatty acids in the total fatty acids were decreased (P < 0.01) by CT at 50 μg/ml. Transmission electron microscopy showed that CT disrupted the outer membrane structure.
Anti–E. coli O157:H7 activity of PPC CT at levels of up to 200 μg/ml was bacteriostatic rather than bactericidal, and the mechanism of anti–E. coli activity may involve alteration in the fatty acid composition and disruption of the outer membrane of the cell.
Document Type: Research Article
Agriculture & Agri-Food Canada Research Centre, Lethbridge, Alberta, Canada. firstname.lastname@example.org
Agriculture & Agri-Food Canada Research Centre, Lethbridge, Alberta, Canada
Department of Animal Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
Agriculture & Agri-Food Canada Research Centre, Lethbridge, Alberta, Canada; Department of Veterinary Medicine, Inner Mongolia Agricultural University, China
Alberta Agriculture and Rural Development, Lethbridge Agriculture Centre, Lethbridge, Alberta, Canada
Publication date: April 1, 2013
More about this publication?
IAFP members must first sign in on the right to access full text articles of JFP
First published in 1937, the Journal of Food Protection®
, is a refereed monthly publication. Each issue contains scientific research and authoritative review articles reporting on a variety of topics in food science pertaining to food safety and quality. The Journal
is internationally recognized as the leading publication in the field of food microbiology with a readership exceeding 11,000 scientists from 70 countries. The Journal of Food Protection®
is indexed in Index Medicus, Current Contents, BIOSIS, PubMed, Medline, and many others.
Print and online subscriptions are available to Members and Institutional subscribers. Online visitors who are not IAFP Members or journal subscribers will be charged on a pay-per-view basis. Information can be obtained by calling +1 800.369.6337; +1 515.276.3344; fax: +1 515.276.8655, E-mail: email@example.com
or Web site: www.foodprotection.org
- Information for Authors
- Submit a Paper
- Subscribe to this Title
- Membership Information
- Information for Advertisers
- ingentaconnect is not responsible for the content or availability of external websites
- In this:
- By this:
- In this Subject:
Nutrition & Food
- By this author:
Ominski, K. H.
Krause, D. O.
Acharya, S. N.
Wittenberg, K. M.
Liu, X. L.
McAllister, T. A.