Eugenol as a Seed Treatment for Controlling Escherichia coli O157:H7 and Salmonella Typhimurium in Basil (Ocimum basilicum L.) seeds under Controlled Environmental Agriculture

Abstract

Recent foodborne outbreaks linked to basil (Ocimum basilicum L.) highlight the urgent need for effective intervention strategies covering the entire production cycle from seed to harvest. Foodborne pathogens, particularly E. coli O157:H7 and S. Typhimurium, pose significant public health risks when associated with fresh produce. Seeds serve as a primary vector for pathogen transmission, with contamination often originating from irrigation water, manure, or cross-contamination during handling. Traditional seed disinfection methods, such as chlorine-based treatments and hydrogen peroxide, have limited efficacy in reducing pathogens while maintaining seed viability. Eugenol has been shown to be an effective foodborne pathogen intervention in a variety of produce types. This study investigates the potential of eugenol (0.5%, 0.75%, 1.0%), a phenolic monoterpenoid, as a seed treatment to control E. coli O157:H7 and S. Typhimurium and quality parameters on basil seeds over 14 days. All eugenol concentrations reduced pathogen loads by 4-5 log CFU/g at hr 0. However, antimicrobial efficacy declined significantly over time, with regrowth observed by 48 hrs, resulting in microbial levels not significantly different from the untreated control (p > 0.05). The 0.5% eugenol treatment consistently minimized negative impacts on germination rates (p > 0.05) and biomass (p < 0.05), offering the best balance between microbial control and plant health. These results underscore eugenol's potential as a short-term surface disinfectant for basil seeds and emphasize the need for combined strategies to sustain long-term efficacy.

Keywords: Basil (Ocimum basilicum L.); Escherichia coli O157:H7; Eugenol solutions; Salmonella Typhimurium; Seed treatments.