Location: Produce Safety and Microbiology ResearchTitle: Salmonella spp. dynamics in wild blueberry, Vaccinium angustifolium Aiton Author
|Drummond, Frank - University Of Maine|
|Tadepalli, Shravani - University Of Maine|
|Camire, Mary Ellen - University Of Maine|
|Davis-dentici, Katherine - University Of Maine|
|Bushway, Alfred - University Of Maine|
|Yarborough, David - University Of Maine|
Submitted to: World Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2017
Publication Date: 2/11/2017
Citation: Wu, V.C., Drummond, F., Tadepalli, S., Camire, M., Davis-Dentici, K., Bushway, A., Yarborough, D.E. 2017. Salmonella spp. dynamics in wild blueberry, Vaccinium angustifolium Aiton. World Journal of Microbiology. 4(1):64-71.
Interpretive Summary: The presence of wildlife in wild blueberry fields has been identified as the primary potential source of some human pathogens, specifically Escherichia coli O157:H7 and Salmonella spp.. The threats to U.S. food safety due to microbial human pathogens have affected farm operations in many states. The objective of this paper was to quantify the major farm management and ecological factors that influence Salmonella spp. associated with wild blueberry fruit. The present study has shown that Salmonella spp. contamination in a wild blueberry field is a dynamic phenomenon, dependent upon management practices implemented by growers and the resulting soil and plant nutrient profile, as well as, fruit quality and the background microbial community associated with fruit colonization. This research provides new hypotheses to test so that a model of Salmonella spp. ecology in the wild blueberry agro-ecosystem can be put forth. Knowledge of Salmonella spp. ecology may provide insight into minimizing consumer exposure to this particular foodborne pathogen.
Technical Abstract: A six-year field study was conducted in the two major wild, or lowbush, blueberry growing regions in Maine, Midcoast and Downeast. This study used data from two cropping cycles (four years) to model the dynamics of Salmonella spp. prevalence in wild blueberry fields (Vaccinium angustifolium Aiton). A path diagram based upon structural equation modeling suggests that beyond annual variation, the type of cropping system determined wild blueberry production methods of fertilization and fungicide applications for control of plant pathogens that then both affect the prevalence of Salmonella spp. Fungicide applications have a direct negative effect on Salmonella spp. prevalence and the microbial community on the fruit that positively affects Salmonella spp. prevalence. Fertilizer application has an indirect effect on Salmonella spp. prevalence by determining soil fertility that then determines the blueberry plant nutrient profile. This then determines specific nutrient levels in the plant, especially Cu, K, Mg, Mn, and K. These nutrients (especially Ca, K, and Mg and to a lesser extent Cu, Mn, and Zn) directly affect Salmonella spp. prevalence in a complex mix of indirect and direct, and negative and positive interactions, including the regulation of sugars in the fruit that appears to have a negative effect on Salmonella spp. prevalence. The conceptual model presented in this study generates several new hypotheses to test regarding the ecology of Salmonella spp. in commercial wild blueberry fields in Maine, USA.