Antimicrobial activity evaluation of nano ZnO-loaded nanoliposomes against Bacillus cereus (ATCC 11778) and Pseudomonas aeruginosa (ATCC 9027) Abstract

In this research, in-vitro time- kill curve effect of nano-ZnO loaded nanoliposomes against Bacillus cereus (ATCC 11778) and Pseudomonas aeruginosa (ATCC 9027) were evaluated. Thin layer hydration sonication and heat methods were evaluated to preparation of nano-ZnO loaded nanoliposomes at different level of lecithin: nano-ZnO ratio (5:1, 15:1, and 25:1 w/w). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of nano-ZnO loaded nanoliposomes and free nano-ZnO against Bacillus cereus and Pseudomonas aeruginosa were determined. Results showed that the encapsulation of nano-ZnO in nanoliposome systems significantly increased their antimicrobial activities. Nano-ZnO loaded nanoliposomes were prepared at the highest ratio of lecithin: nano-ZnO ratio (25:1 w/w) showed higher antimicrobial activity compared to those prepared by heat method. From the time- kill curves, the log phase growth of Escherichia coli (8 hours) and Staphylococcus aureus (7 hours) in the medium containing nano-ZnO loaded nanoliposomes prepared through the thin layer hydration sonication at the highest level of lecithin: nano-ZnO ratio (25:1 w/w) at MIC and MBC values decreased to 3 and 3 hours and to 1 and less than 1 hours, respectively.