Inactivation of Polymicrobial Biofilms of Foodborne Pathogens Using Epsilon Poly-L-Lysin Conjugated Chitosan Nanoparticles

Xingjian Bai; Luping Xu; Atul Kumar Singh; Xiaoling Qiu; Mai Liu; Ahmed Abuzeid; Talaat El-Khateib; Arun K Bhunia

doi:10.3390/foods11040569

Inactivation of Polymicrobial Biofilms of Foodborne Pathogens Using Epsilon Poly-L-Lysin Conjugated Chitosan Nanoparticles

Foods. 2022 Feb 16;11(4):569. doi: 10.3390/foods11040569.

Authors

Xingjian Bai^{1

2}, Luping Xu^{1

2}, Atul Kumar Singh^{1

3}, Xiaoling Qiu¹, Mai Liu¹, Ahmed Abuzeid^{4

5}, Talaat El-Khateib⁴, Arun K Bhunia^{1

2

6}

Affiliations

¹ Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN 47907, USA.
² Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA.
³ Clear Labs, San Carlos, CA 94070, USA.
⁴ Department of Food Hygiene, Assiut University, Assiut 71515, Egypt.
⁵ Animal Health Research Institute, Agriculture Research Center, Giza, Cairo 12618, Egypt.
⁶ Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA.

Abstract

A mixed culture (polymicrobial) biofilm provides a favorable environment for pathogens to persist in the food processing environment and to contaminate food products. Inactivation and eradication of such biofilms from food processing environments are achieved by using harsh disinfectants, but their toxicity and environmentally hostile characteristics are unsustainable. This study aims to use food-grade natural nanoparticulated antimicrobials to control mixed-culture biofilms. Chitosan, a natural broad-spectrum antimicrobial biopolymer (polysaccharide) from crustaceans, was derivatized to produce chitosan nanoparticles (ChNP) as a carrier for another broad-spectrum antimicrobial agent, ε-poly-L-lysine (PL), to synthesize ChNP-PL conjugate. The antimicrobial activity of ChNP and ChNP-PL was tested against mixed-culture biofilms. ChNP-PL (~100 nm) exhibited a synergistic antimicrobial and anti-biofilm effect against mono or mixed-culture biofilms of five foodborne pathogens, including Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica serovar Enteritidis, Escherichia coli O157:H7, and Pseudomonas aeruginosa. ChNP-PL treatment prevented biofilm formation by mono or mixed cultures of L. monocytogenes, P. aeruginosa, and E. coli O157:H7, and bacterial counts were either below the detection limit or caused 3.5-5 log reduction. ChNP-PL also inactivated preformed biofilms. In monoculture biofilm, ChNP-PL treatment reduced L. monocytogenes counts by 4.5 logs, S. Enteritidis by 2 logs, E. coli by 2 logs, and S. aureus by 0.5 logs, while ChNP-PL had no inhibitory effect on P. aeruginosa. In vitro mammalian cell-based cytotoxicity analysis confirmed ChNP-PL to have no deleterious effect on intestinal HCT-8 cell line. In conclusion, our results show ChNP-PL has strong potential to prevent the formation or inactivation of preformed polymicrobial biofilms of foodborne pathogens.

Keywords: E. coli; Listeria; Pseudomonas; S. aureus; Salmonella; biofilm; chitosan nanoparticle; inactivation; multi-pathogen; ε-poly-L-lysine.

Grants and funding

AID-263-A-15-00002/National Academies of Sciences, Engineering, and Medicine