Solving recently emerging issues of antibiotic-resistant bacteria in water have been a challenging task in the perspectives of cost-effective treatment, the absence of byproduct formation from post-treatment of contaminated water, and microbial inactivation efficacy of trace contaminants. In the present study, newly developed ZnO nanoparticle (NP)-encapsulated alginate biopolymer beads were applied for treating highly contaminated water with two model antibiotic-resistant bacteria (Escherichia coli DH5-α and Pseudomonas aeruginosa) at an initial concentration of 108 CFU mL-1 over 6 h of reaction time. The bacterial inactivation was found to be highly effective, with the removal rates of 98% and 88% on E. coli DH5-α and P. aeruginosa, respectively, and the removal rate was proportional to the amount of the ZnO nanocomposite and contact time. While the primary mechanism involved the generation of reactive oxygen species (ROS), the electro-steric effect by free carboxylic functional groups available as metal-binding sites and the resultant adsorption of metal ions released from NPs was not trivial, as observed in scanning electron microscopy (SEM) images, in which significant bacterial cell damages were found. The present study showcased the treatment efficacy of ZnO NP–alginate beads to be highly promising, especially for point-of-use with multiple benefits including but not limited to reusability of used beads, immobilization of nanoparticles within the biopolymer matrix, and utilization of small nanoparticle sizes.

New antimicrobial approaches for the treatment of antibiotic-resistant bacteria in water

2019 Spring National Meeting

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