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

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Abstract Ascribe Bioscience is developing a novel technology to prevent foodborne outbreaks caused by the consumption of edible sprouts. Sprouts are highly vulnerable to infection with human enteric bacterial pathogens at the seed stage. These pathogens then grow exponentially in the warm and humid conditions used for sprouting. Even low initial bacterial counts on seeds can result in unsafe microbial loads by the end of sprout production and processing. Moreover, the internalization of contaminating bacteria into seed tissues contaminates the sprout tissues from inside, rendering the application of antimicrobials largely ineffective. Sprouts have emerged as a significant source of foodborne illness and have become a public health hazard. Between 1996 and 2017, the U.S. experienced 58 foodborne illness outbreaks associated with sprouts, encompassing at least 1,953 illnesses, 212 hospitalizations, and 5 deaths. According to the FDA, no single treatment so far has been shown to eliminate pathogens on seeds or sprouts that cause foodborne illness. Ascribe Bioscience will use a natural, microbiome-derived molecule that activates and/or prime plant defenses at the seed stage, thereby conferring to sprouts an enhanced resistance against contamination by disease-causing bacterial pathogens. Ascribe's proposed treatment technology has the potential to dramatically improve the safety of edible sprouts by addressing both external and internal bacterial contamination. In Phase I, Ascribe has established the feasibility of the technology for the prevention of outbreaks related to human consumption of sprouts by demonstrating that treatment with our molecule can prevent Salmonella growth during the sprouting process in alfalfa. In Phase II, we will finalize the sprout seed treatment formulation and expand testing to a broader spectrum of sprout-pathogen systems. To support commercialization, we will perform toxicity and residue testing for regulatory approval, and refine synthesis methodologies to enable large-scale production of the active ingredient. The specific aims of this Phase II project are 1) Refine treatment formulation, including optimized formulation development, determination of the minimum effective dose and treatment duration, comparison of the effectiveness of the formulation versus the sprout industry-standard treatments, and measuring the effects of the formulation on germination, growth and sprout quality; 2) Test the efficacy of treatments against other illness-causing pathogens on a variety of sprout types, and evaluate it's role in altering bacterial abilities to form biofilm; 3) Demonstrate safety via toxicology studies and residue testing to support EPA approval; 4) Develop methods to scale the synthesis of active ingredient to pilot scale, and 5) Investigate the ability of the molecule to provide post-harvest protection to leafy greens. The proposed research is expected to yield commercial products that will prevent or dramatically reduce the incidence of sprout-related foodborne outbreaks.