Control of Listeria monocytogenes in Food Processing Facilities by Competitive Exclusion Microorganisms

This research determined whether the introduction of harmless bacteria in the food processing facilities would reduce and/or eliminate Listeria monocytogenes via competitive exclusion.

Download final report

Objectives

To develop a method to prevent contamination of L. monocytogenes in foods by eliminating/reducing the occurrence of L. monocytogenes in the environment of food processing facilities.

Conclusions

Nine inhibitory bacterial isolates were identified as Enterococcus durans (6 isolates), Lactococcus lactis subsp. lactis (2 isolates), and Lactobacillus plantarum (1 isolate). The anti-L. monocytogenes properties of these isolates were determined in biofilms of L. monocytogenes on stainless steel coupons at 37°, 15°, 8° and 4°C. Results revealed that all of nine isolates were highly inhibitory (more than 5 log10 L. monocytogenes cfu/cm2 growth inhibition to a undetectable level as determined by a direct plating method) at 37°C for 24 h when compared with a control biofilm of L. monocytogenes only. At 4° and 8ºC, three isolates (E. durans 141-1 and 152; Lc. lactis subsp. lactis C-1-92) were highly inhibitory to L. monocytogenes through 35 days (>4 log₁₀ L. monocytogenes/cm2 growth inhibition). These three bacterial isolates appear to be excellent competitive inhibition candidates to control L. monocytogenes in biofilms at environmental temperatures of 4°, 8º and 37°C.

Deliverable

This study identified non-pathogenic organisms that compete with Lm in the RTE environment. Sanitation solutions containing these organisms are currently undergoing commercial trials in RTE meat and poultry plants. The first paper from this research will publish in July.