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Title: Comparison of the effect of monolaurin on the growth and survival of Enterococcus and Salmonella

item Hinton Jr, Arthur
item Jackson, Charlene

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/10/2008
Publication Date: 12/7/2008
Citation: Mansour, E.O., Hinton Jr, A., Jackson, C.R., Reddy, G.P. 2008. Comparison of the effect of monolaurin on the growth and survival of Enterococcus and Salmonella [abstract]. Conference of Research Workers in Animal Diseases. December 7-9,2008. Chicago, IL. P110(45P).

Interpretive Summary: none

Technical Abstract: The effect of monolaurin, a glyceride ester derivative of lauric acid, on the growth of Enterococcus sp. and Salmonella sp. was determined. Salmonella is considered one of the main pathogens in poultry industry, and Enterococcus is an important indicator of fecal contamination and an important cause of nosocomial infections. Monolaurin is an antimicrobial agent that is also used as a food preservative. We have investigated its efficacy as an agent for post-harvest pathogen reduction in the chicken processing industry. Tryptic soy broth (TSB) supplemented with monolaurin at concentrations of 0, 10, 50, 100, 250, 1000, 2000, or 4000 µg/ml was inoculated with 102, 104, or 106 cfu/ml of Salmonella or Enterococcus. The inoculated media was placed in the Bioscreen C Microbiology Analyzer programmed to monitor the growth of the cultures during incubation at 37°C for 36 hours. Growth curves indicated that increasing the concentration of monolaurin produced greater inhibition to Enterococcus growth than Salmonella growth. The lower concentrations of monolaurin (10, 50, or 100 µg/ml) exhibited no inhibition or a lower percentage of inhibition of Salmonella sp. growth. Salmonella growth was reduced between 0-31%, compared to the Enterococcus sp. growth which was reduced between 0 to74 % according to the bacterial and monolaurin concentrations. The higher inhibitory effects were prevalent in the lower bacterial cell concentrations cultured in the higher monolaurin concentrations in Enterococcus more than Salmonella. Monolaurin at 250 µg/ml inhibited growth of 102,104 or 106 cfu/ml of Enterococcus by 77%, 81%, or 0% respectively; 500µg/ml inhibited growth by 80%, 87% or 71%; 1000 µg /ml inhibited growth by 89%, 87% or 72%; 2000 µg/ml inhibited growth by 95%, 100, or 75%; and 4000 µg/ml inhibited growth by 100%, 100% or 96% respectively. Monolaurin inhibited growth of 102, 104 or 106 cfu/ml of Salmonella sp. by 46%, 30%, or 34%, respectively at 250µg/ml; 37%, 36%, or 52% at 500µg/ml; 50%, 49%, or 55% at 1000µg/ml; 70%, 50%, or 63% at 2000 µg/ml; and 91%, 80%, or 65 % at 4000µg/ml. In vitro trials conducted by enumerating bacteria recovered after mixing cultures of Salmonella or Enterococcus for up to 24 hours at the concentrations of 0, 2000, or 4000 µg/ml of monolaurin revealed no bactericidal effect on the number of Salmonella or Enterococcus recovered from the bacterial suspension. The efficacy of monolaurin requires further investigation as the findings of this study do not support the use monolaurin as a sanitizer for chicken carcasses, since even high concentrations of this compound are not bactericidal towards the important pathogen, Salmonella.