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Evaluation of the use of lactic acid bacteria to control pathogens on alfalfa sprouts

Marsha R Wilderdyke, University of Nebraska - Lincoln

Abstract

Several studies have investigated the control of pathogens on alfalfa sprouts and some treatments have been shown to be effective in reducing pathogen populations. However, control methods investigated thus far only provide pathogen control at a given point in the sprouting process leaving the sprouts vulnerable at other times during sprouting and storage. Competitive inhibition of pathogens with LAB (lactic acid bacteria) may provide pathogen control throughout the sprouting process and up to consumption. The purpose of this study was to isolate and identify LAB with the intention of adding selected isolates to alfalfa sprouts to inhibit the growth of pathogens during sprouting and storage. Fifty-eight LAB isolates were obtained from alfalfa seeds and sprouts. Based on the agar spot test, all pathogens were inhibited by 32 (55%) of the isolates, Salmonella enterica by 56, Escherichia coli O157:H7 by 49, and Listeria monocytogenes by 41. The isolates were identified using the Analytical Profile Index for carbohydrate utilization, and the isolate L7 was identified using 16s rRNA sequence analysis. Isolate L7 and an isolate previously obtained, D3, were evaluated for competitive inhibition of pathogens in laboratory media. Pathogen populations were significantly reduced by day 5. The isolates were added to seed soak water with pathogen inoculated seeds. During sprouting and storage, LM showed a significant reduction compared to the Control while EC and SE were consistently higher than the Control, though significance was borderline. For this reason, the interactions of these LAB cultures and EC and SE need to be elucidated by further study. The effects of LAB on Gram negative bacteria have been largely overlooked in the literature. It is suggested that in competitive inhibition studies, the effects of LAB on Gram negative pathogens be addressed concurrently with Gram positive pathogens. ^

Subject Area

Agriculture, Food Science and Technology|Biology, Microbiology

Recommended Citation

Wilderdyke, Marsha R, "Evaluation of the use of lactic acid bacteria to control pathogens on alfalfa sprouts" (2004). ETD collection for University of Nebraska - Lincoln. AAI3159569.
http://digitalcommons.unl.edu/dissertations/AAI3159569

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