(347b) Fatty Acids Library Screening and Their Synergistic Effect with Nisin on Inhibiting Biofilm and Persister Formation of Listeria Monocytogenes

Jiacheng Zhou, Xing Jin, Kuili Fang, and Seok Hoon Hong^*

Department of Chemical and Biological Engineering, Illinois Institute of Technology,Chicago, IL 60616, USA

*Corresponding author: shong26@iit.edu

Tel: (+1) 312 567 8950

ABSTRACT

A foodborne pathogen, Listeria monocytogenes, causes a life-threatening disease listeriosis and threatens the food safety. The FDA-approved antimicrobial peptide nisin has been used to prevent contamination of food product from Gram-positive pathogens including L. monocytogenes. However, the formation of biofilms and persisters (i.e., metabolically dormant bacterial population) has resulted in the failure of nisin treatment. Fatty acids, which have been known to exhibit antimicrobial activities, are widely used for therapeutics, food preservation, and agriculture. From the screening of fatty acid library, we found that two fatty acid compounds are effective in inhibiting biofilms and persister formation of Gram-negative pathogens. We also investigated whether the fatty acid treatment in combination with nisin promotes inactivation of L. monocytogenes, especially biofilms and persisters. The fatty acid only treatment reduced the level of biofilms and persisters, while nisin only treatment resulted in the development of resistant population of L. monocytogenes ATCC19115 strain. However, the co-treatment of the fatty acid and nisin synergistically enhanced the killing of L. monocytogenes by decreasing the number of survived cells and inhibiting Listeria biofilms. These results are particularly important in improving food safety in that the food-grade fatty acids can be applied to repress the occurrence of resistant mechanisms of foodborne pathogens by inhibiting biofilm and persister cell formation.