The inhibitory effect of plant extracts on growth of the foodborne pathogen, Listeria monocytogenes

Authors: CERUSO, MARINA - The University Of Naples Federico Ii; CLEMENT, JASON - California Natural Products; ZHANG, FANGYUAN - Villanova University; HUANG, ZUYI - Villanova University; PEPE, TIZIANA - The University Of Naples Federico Ii; ANASTASIO, ANIELLO - The University Of Naples Federico Ii; Liu, Yanhong

Submitted to: Antibiotics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2020
Publication Date: 6/11/2020
Citation: Ceruso, M., Clement, J., Zhang, F., Huang, Z., Pepe, T., Anastasio, A., Liu, Y. 2020. The inhibitory effect of plant extracts on growth of the foodborne pathogen, Listeria monocytogenes. Antibiotics. 9(6) https://doi.org/10.3390/antibiotics9060319.
DOI: https://doi.org/10.3390/antibiotics9060319

Interpretive Summary: Listeria monocytogenes is an important foodborne pathogenic bacterium that causes a disease known as listeriosis. A number of technologies and antimicrobials have been applied to control the presence of L. monocytogenes in food and food processing environments; however, these are often ineffective and have some toxicity for humans. Thus, the use of natural antimicrobials is preferred by consumers due to their ability to inhibit the growth of foodborne pathogens but not prompt negative safety concerns. Among natural antimicrobials, plant extracts have been explored to some extent to inactivate L. monocytogenes. However, there is a large amount of these types of plants and their extracts, and their active compounds remain unexplored. Approximately, 800 different extracts from plants found worldwide were evaluated for their effectiveness in inhibiting the growth of L. monocytogenes. Twelve of the plant extracts showed notable activity against the pathogen, and the concentrations required for growth inhibition were determined. Furthermore, the effect of these extracts on L. monocytogenes cells was determined at the microscopic level. Results indicated that the extracts caused extensive cell damage and the loss of cell appendages that are involved in movement (flagella). Applications of this study include the use of these plant extracts and/or their specific active compounds as new preservatives for the food industry and consumers to reduce the risk of contamination from L. monocytogenes.

Technical Abstract: Listeria monocytogenes is a foodborne pathogen responsible for about 1,600 illnesses each year in the U.S. and about 2,000 confirmed invasive human cases in EU countries. Several technologies and antimicrobials have been applied to control the presence of L. monocytogenes in food. Among these, the use of natural antimicrobials is preferred by consumers. This is due to their ability to inhibit the growth of foodborne pathogens but not prompt negative safety concerns. Among natural antimicrobials, plant extracts have been used to inactivate L. monocytogenes. However, there is a large amount of these types of extracts and their active compounds remain unexplored. The aim of this study was to evaluate the antibacterial activity against L. monocytogenes of about eight hundred plant extracts derived from plants native to different countries worldwide. The Minimal Inhibitory Concentrations (MICs) were determined, and scanning electron microscopy (SEM) was used to verify how the plant extracts affected L. monocytogenes at the microscopic level. Results showed that twelve of the plant extracts had inhibitory activity against L. monocytogenes. Future applications of this study could include the use of these plant extracts as new preservatives to reduce the risk of contamination in the food industry from L. monocytogenes.