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P3-38 Plant-Microbe Factors Influencing Salmonella Survival and Growth on Alfalfa Sprouts and Microgreens

Wednesday, July 12, 2017
Exhibit Hall (Tampa Convention Center)
Elizabeth Reed , U.S. Food and Drug Administration , College Park , MD
Christina Ferreira , U.S. Food and Drug Administration , College Park , MD
Rebecca Bell , U.S. Food and Drug Administration , College Park , MD
Eric Brown , U.S. Food and Drug Administration, Center for Food Safety & Applied Nutrition , College Park , MD
Jie Zheng , U.S. Food and Drug Administration , College Park , MD
Introduction:  Microgreens have not been associated with an outbreak, but are similar to sprouts, which have been associated with numerous foodborne outbreaks. Understanding the risks of Salmonella contamination and its effects on rhizosphere microbial communities will enable a better understanding of host-pathogen dynamics in these commodities.

Purpose:  These studies were performed to examine the factors that affect Salmonella survival and growth on alfalfa sprouts and microgreens and to investigate the factors influencing the rhizosphere microbial communities during sprouting.

Methods: Different Salmonella serovars (Hartford and Cubana) at inoculation levels (101, 10-1, and 10-2 CFU/ml) were evaluated for survival and growth on alfalfa sprouts using most probable number (MPN) method. In addition, edible/nonedible portions of microgreens and various soil types were also tested. Community level physiological profiles (CLPP) of sprout/microgreen rhizospheres were characterized with Biolog EcoPlates at different time points during sprouting

Results:  Overall, inoculation level, serovar, and inoculation level by serovar interaction significantly affected the survival/growth of Salmonella in alfalfa sprouts (P<0.0001), but had no significant effect in microgreens (P=0.57719, and P=0.15348). At lower inoculation levels, Hartford was able to survive/grow better, while Cubana did significantly better than Hartford at 101CFU/ml. Soil type played an important role in Salmonella survival/growth in microgreens (P=0.00946). CLPP analysis showed significant changes in the microbial functional diversity during sprouting for alfalfa sprouts, but not for microgreens. Salmonella contamination did not confer significant changes in the corresponding rhizosphere microbial community in both sprouts and microgreens.

Significance: The growth and persistence of S. enterica on alfalfa sprouts, but not microgreens, is serovar and inoculation level dependent. CLPP analysis revealed the change in rhizosphere bacterial functional diversity was host-dependent, but independent of Salmonella contamination. This data will aid further design of preventive strategies of Salmonella contamination in sprouts and microgreens.

Back to: Poster Session 3 – Low-water Activity Foods, Packaging, Produce, Microbial Food Spoilage, Antimicrobials, Laboratory and Detection Methods, Water
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