Comparison methods for the evaluation of bacteriocin potency against E.coli O157:H7 in milk

Saab Khudhir, Zina

	Comparison methods for the evaluation of bacteriocin potency against E.coli O157:H7 in milk
iraq journal of market research and consumer protection
Article 1, Volume 6, Issue 2, 2014, Pages 188-199
Author
Zina Saab khudhir
Abstract
The main objective of the present study was to evaluate the antagonistic effect of reference strain Lactobacillus acidophilus ROO52 bacteriocin againstEscherichia coli. O157:H7 with a comparison of disk diffusion agar, well diffusion agar ,spot method and modified agar.overlays methods. A total of 30 raw milk samples were collected randomly at weekly intervals from different local markets in Baghdad province during the period from the beginning of January 2013 till the end of April 2013). The prevalence of E .coli O157:H7 in raw milk samples was 20% by using the modern chromogenic media with serological latex agglutination test kit. The data revealed that the method applied had a significant (P ˂ 0.05) effect on the antimicrobial potency of the crude bacteriocin against E. coli O157:H7. The average diameter of the inhibition zone of crude bacteriocin againstE .coli O157:H7 by both, agar disk diffusion method and the agar well diffusion method was (10mm) respectively and showed a potency of (62.5%) while that produced by the agar spot diffusion method was (8mm) and showed a potency of (50%) while that produced by the modified agar overlays method was (16mm) which exhibited significantly (P˂ 0.05) the highest antimicrobial potency (100%) compared to that produced by the above mentioned three methods. Results showed that the modified agar overlays method was the most suitable and reliable method for assessing the antagonistic effect of the crude bacteriocin against E. coli O157:H7.
Keywords
coli O; bacteriocin potency; Milk

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