Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: Autoinducer 2-Like Activity Associated with Foods and Its Interaction with Food Additives

Authors
item Lu, Lingeng - TX A&M UNIVERSITY
item Hume, Michael
item Pillai, Suresh - TX A&M UNIVERSITY

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 2, 2004
Publication Date: July 1, 2004
Citation: Lu, L., Hume, M.E., Pillai, S.D. 2004. Autoinducer 2-like activity associated with foods and its interaction with food additives. Journal of Food Protection. 67:1457-1462.

Interpretive Summary: There is concern that the use of antibiotics as growth promoting agents in agriculture can result in the development of antibiotic resistant bacteria. The objective of this study was to understand the relationships existing between exposure to low levels of tetracycline, activity of the bacterial communication molecule called AI-2, and development of antibiotic tolerance in E. coli. Laboratory studies using two tetracycline-resistant and one tetracycline-sensitive E. coli isolates were performed. Though all three isolates produced AI-2, they had differing AI-2 activities in response to exposure to low levels of tetracycline. Results indicate that AI-2 increases the ability of tetracycline-sensitive E. coli to survive low levels of tetracycline. Increased AI-2 production can protect the bacterial cells from tetracycline and lead to the development of tetracycline-tolerant bacteria.

Technical Abstract: There is concern that the use of antibiotics as growth promoting agents in agriculture can result in the development of antibiotic resistant commensal and pathogenic microbes. The objective of this study was to understand the relationships existing between exposure to sub-therapeutic tetracycline, AI-2 activity and antibiotic tolerance development in E. coli. Laboratory studies using two tetracycline-resistant and 1 tetracycline-sensitive E. coli isolates were performed. Though all three isolates produced AI-2, they had differing AI-2 activities in response to sub-therapeutic tetracycline exposure. In the presence of tetracycline, the Tet^s E. coli strain continued to have increasing AI-2 activity even after 20 hours of exposure to the antibiotic (2ug/ml). Results indicate that AI-2 actually enhances the ability of the tetracycline-sensitive E. coli strain to survive sub-therapeutic tetracycline stress (10ug/ml). About 87% of the Tet^s E. coli strain survived 4 hours of exposure to chlortetracycline in media containing 80% of AI-2 cell-free supernatant. After 20 hours of exposure, the 69% survival rate of the Tet^s strain was still significantly higher (P<0.05) than in the control treatments. There was, however, no difference between the survival of the Tet^s strain when exposed to only 20% of AI-2 cell-free supernatant. The enhanced AI-2 activity can protect the cells from tetracycline stress and lead to the development of tetracycline-tolerant sub-populations which can serve as a selective advantage.

Last Modified: 10/25/2014
Footer Content Back to Top of Page