Preventing outbreaks of foodborne pathogenic bacteria in edible sprouts via novel resistance-conferring seed treatments

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Abstract One of the most severe foodborne outbreaks in Europe, and the second-largest “Shiga toxin-producing” E. coli outbreak worldwide, was traced to E. coli O104: H4 in fresh fenugreek sprouts from a farm in Germany. It affected more than 4,075 individuals in 16 countries and included 908 cases complicated by hemolytic uremic syndrome (HUS) and 50 deaths. In the U.S., sprouts were implicated as the cause of 58 foodborne outbreaks between 1996 and 2017, encompassing at least 1,953 illnesses, 212 hospitalizations, and 5 deaths. Raw and lightly- cooked edible sprouts pose high risk for outbreaks of foodborne illness which typically originate in the seeds (vs. processing condition genesis of typical plant foodborne illnesses). While seeds contaminated with small amounts of human enteric pathogens, such as Salmonella enterica, Escherichia coli and Listeria monocytogenes have little to no impact on final non-sprout field grown crops, the distinct warm, humid growing conditions of sprouts serve to dramatically amplify growth of these pathogens to dangerous levels.2-5 As the consumption of edible sprouts, including alfalfa, mung bean and clover continues to increase worldwide, largely due to their short growing period, easy availability and high nutritive value,5 so too does the risk of sprout‐related foodborne illness outbreak. The FDA has expressed serious concern over the increasing number of outbreaks. While the FDA recommends soaking the seeds in 20,000 ppm solution of calcium hypochlorite, as well as applying a least one approved antimicrobial treatment immediately before sprouting,6 high concentrations of antimicrobials fail to completely eliminate bacteria from seed, particularly those that have infiltrated seed tissue. According to the agency, “There is no single treatment so far that has been shown to completely eliminate pathogens on seeds or sprouts that cause foodborne illness without affecting germination or yield.” To prevent outbreaks of foodborne pathogenic bacteria in edible sprouts, Ascribe Bioscience is developing novel resistance-conferring seed treatments based on a natural, microbiome-derived molecule that has been shown to activate a plant's natural defenses to provide protection against a broad range of pathogens in a variety of crops, both pre- and post-emergence. To establish the feasibility of the proposed approach as a means to effectively confer protection to sprouts against human enteric pathogens, Phase I development will target four specific aims: 1) Develop an efficacious formulation for sprout seed treatment based on the microbiome-derived molecule, 2) Test the efficacy of the formulation against human enteric pathogens, 3) Test the efficacy of the seed treatment against human enteric pathogens during seed production and after harvest, 4) Test the efficacy of additional related molecules on growth inhibition of human enteric pathogens. In Phase II, we will finalize the sprout seed treatment formulation and conduct broad spread challenges on other types of spouts. Once fully developed, this intervention has the potential to reduce sprout- related infections and outbreaks.