|Park, S - TX A&M UNIVERSITY|
|Woodward, C - TX A&M UNIVERSITY|
|Birkhold, S - TX A&M UNIVERSITY|
|Ricke, S - TX A&M UNIVERSITY|
Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 2, 2003
Publication Date: January 20, 2004
Citation: Park, S.Y., Woodward, C.L., Birkhold, S.G., Kubena, L.F., Nisbet, D.J., Ricke, S.C. 2004. The combination of zinc compounds and acidic pH limits aerobic growth of a Salmonella typhimurium poultry marker strain in rich and minimal media. Journal of Environmental Science and Health. B39:199-207. Interpretive Summary: Zinc is an essential trace mineral found as a common micronutrient in human milk, infant formula, as well as enriched dairy and fruit products. In poultry, zinc is an important trace mineral that is necessary for many critical processes such as growth, bone development, feathering, enzyme structure, and cellular and immune system functions. Dietary zinc may also influence growth of food-borne organisms such as Salmonella. Various zinc compounds have been shown to slow down or stop growth of Salmonella typhimurium in test tubes. Studies in chickens involving feeding moderate to high levels of zinc containing diets to induce molting in laying hens showed decreased Salmonella enteritidis colonization, when compared to hens receiving no feed. It is known that a more acidic (lower pH) condition slows down the growth of Salmonella. The present study was conducted to examine the combined effects of zinc compounds with different acidic pH levels on the growth of Salmonella typhimurium in nutrient rich or minimal nutrient media. The results show that zinc greatly reduces the growth of Salmonella typhimurium in lower acidic media under aerobic atmospheric conditions outside the body of the chicken. This is important because the effectiveness of zinc at lower acidic conditions suggests a potential for use of zinc compounds and acidic conditions to reduce Salmonella on poultry skin and surfaces of other foods, thus reducing the risk of consumption of Salmonella contaminated foods. However, studies using chicken carcasses and other foods must be conducted to determine the effectiveness of the zinc compounds.
Technical Abstract: The objective of the present study was to examine the combined effects of zinc compounds with different acidic pH levels on the aerobic growth of a S. typhimurium poultry isolate under either rich or minimal media. When overall main effects of pH levels of medium or concentrations of Zn compounds were compared, growth rates of the S. typhimurium poultry isolate were significantly (p<0.05) decreased by stepwise increase of pH levels of medium (pH 4, 5, 6, and 7) or concentrations (0.67, 3.35, and 6.03%) of Zn compounds (Zn acetate and Zn sulfate). When overall main effects of Zn compounds in minimal medium were compared, growth rates of S. typhimurium poultry isolate were more (p<0.05) reduced by Zn acetate than by Zn sulfate.