Survival of Escherichia coli O157:H7 after application of lactic acid bacteria

Background: Establishing novel preharvest intervention strategies for leafy green growers is of critical need with the rise in foodborne outbreaks associated with these products. Recent studies have shown that lactic acid bacteria (LAB) are able to reduce the presence of Escherichia coli O157:H7 in various food matrices. Electrostatic application of organic acids has been shown to be effective as a postharvest safety intervention to reduce E.coli O157:H7 on leafy greens. The effect of LAB electrostatically applied and sprinkler irrigated once over a 4 week growth cycle was evaluated against E. coli O157:H7 on spinach. Results: The results indicated that E. coli O157:H7 when applied once during the 4 week growth cycle will survive in the soil and spinach leaves at harvest. LAB applied electrostatically and by sprinkler irrigation water on the soil and/or leaf surface within the first 4 weeks of the growing cycle resulted in a significant reduction (almost a 3 log ₁₀ reduction) of E. coli O157:H7 both on the leaf and in the soil at harvest, regardless of the application time (P < 0.01). Conclusion: LAB surface treatments have the potential to improve the safety of leafy green plants as a preharvest food safety intervention when combined with good agricultural practices.