Inactivation of Listeria biofilms on food contact surfaces

The presence of Listeria monocytogenes in food manufacturing facilities remains a significant food safety challenge. Its persistence and ability to form resilient biofilms on various food contact surfaces make it particularly difficult to address, posing risks of cross-contamination in food processing lines. Tackling this challenge requires targeted solutions capable of penetrating biofilms and disrupting Listeria at its source, as biofilm residues enable re-growth and spread of Listeria within production environments.




Phage technology offers an effective solution for the complete inactivation of Listeria biofilms. Bacteriophages (phages) are abundant microorganisms that act as natural agents for balancing bacterial populations on earth by specifically targeting their host bacteria. Specific anti Listeria phages can attach to- and inactivate Listeria biofilm formations up to their source, preventing re-growth and potential cross-contamination at critical control points in processing lines. Phage solution, Phageguard L (PGL) (also known as Listex), contains a specific phage that targets prevalent Listeria spp. encountered in the food industry. Delivered in a liquid solution, it provides a commercially viable tool for HACCP protocols, enabling the control of Listeria on food contact surfaces and inactivation of biofilm formations in hard-to-reach spots, such as crannies and nooks.

Conducted studies of Phageguard L for removal of Listeria biofilms on food contact surfaces

Multiple universities and research institutes have confirmed the efficacy of Phageguard L in inactivating Listeria biofilms on various food contact surfaces commonly used in the food industry. A study conducted by Mississippi State University (Soni KA, Nannapaneni R.1) demonstrated a 3.5-log to 5.4-log reduction of L. monocytogenes biofilm formation on stainless steel following a single treatment with Phageguard L. The treated biofilm included 21 different Lm strains, representing 13 different serotypes.

Research institute IPLA-CSIC (Diana Gutiérrez, Lorena Rodríguez-Rubio, Lucía Fernández, Beatriz Martínez, Ana Rodríguez, Pilar García 2) conducted studies on Listeria biofilm removal on stainless steel and polystyrene. Results showed that a single phage treatment with Phageguard L reduced L. monocytogenes on stainless steel by up to 4.9 log and on polystyrene by up to 6.9 log.

Penetrating Listeria biofilms for effective inactivation

The high efficacy of phage treatment for inactivating Listeria biofilms is due to the ability to penetrate biofilms, whereas traditional interventions mostly interact with the surface of the biofilm. A study on general phage therapy supported by the Hamadan University of Medical Sciences visualized the mechanism of phages for biofilm removal (presented below).

The penetration of Listeria biofilms is essential for inactivation and preventing re-growth. A single treatment of the phage solution, Phageguard L, achieves significant reductions, as demonstrated in various studies. By implementing Phageguard L within HACCP measures, Listeria control and biofilm prevention can be effectively maintained. Pre-existing Listeria biofilms, often found in hard-to-reach spots, can be removed through repeated treatments with Phageguard L, with the number of treatments depending on the biofilm’s age, as observed in industrial applications.

References:

1. Soni KA, Nannapaneni R. Removal of Listeria monocytogenes biofilms with bacteriophage P100. J Food Prot. 2010 Aug;73(8):1519-24. doi: 10.4315/0362-028x-73.8.1519. PMID: 20819365. (here)

2. Diana Gutiérrez, Lorena Rodríguez-Rubio, Lucía Fernández, Beatriz Martínez, Ana Rodríguez, Pilar García, Applicability of commercial phage-based products against Listeria monocytogenes for improvement of food safety in Spanish dry-cured ham and food contact surfaces,
Food Control, Volume 73, Part B, 2017, Pages 1474-1482, ISSN 0956-7135, (here)