Z. Ma, A. Garrido Maestú and K.C. Jeong
University of Florida,
Keywords: chitosan-based Nanoparticles, antimicrobial agents
Summary:We have developed Chitosan nano- and micro-particles, engineered from chitosan, as a natural antimicrobial agent, and results provide promising potential for applications for disease treatment. Chitosan microparticles (CMs) significantly reduced pathogens in the gastrointestinal tract of cattle and in the uteri of cows with metritis. CMs showed excellent antimicrobial activity against a wide range of microorganisms, including clinically important multi-drug resistant pathogens without raising resistant mutants over a period of 15 days. In addition, CMs treatment did not cause cross-resistance, frequently observed with other antibiotics, triggering occurrence of multi-drug resistance. Remarkably, CMs exerted antimicrobial activity in sick cows with metritis and cured the disease. We further enhanced antimicrobial activity by engineering of chitosan nanoparticles (CNs) by testing sonication times and powers, molecular weights of chitosan, cross-linkers and concentrations in relation to the particle sizes as well as their antimicrobial activity. We understood the underlying mechanism of CNs on killing pathogens. Likewise CMs, CNs kill pathogens, including multi-drug resistant microorganisms, by disruption of bacterial cell membranes, probably targeting outer membrane protein A (OmpA) and LPS, resulting in cell death. This antimicrobial activity was also maintained in different animal matrices including uterine fluids and milk samples collected from metritic or subclinical mastitic animals, respectively. Risk assessment of CNs in vitro human cell lines revealed that CNs did not disrupt functionality of the cell organelles and not cause cell cytotoxicity. In addition, in vivo animal model, C. elegans, was employed to evaluate toxicity, and CNs did not affect the lifespan of the challenged animals, indicating CNs do not cause toxicity at working concentrations of antimicrobial activity. Taken together, these results provide insights into chitosan nano- and microparicles as alternative antimicrobial agents to enhance food safety.