| Summary: | 碩士 === 國立海洋大學 === 食品科學系 === 87 === Immobilized antibacterial substrata are carrying the antibacterial component via binding or coating to the surface of solid material, and make the solid material have antibacterial activities. The inhibitory effect of this coating substratum is mainly progressing by contacting or releasing gradually the antibacterial compound. This study takes honeycombs ceramic and carborundum coating with quaternary ammonium salt or silver ions were produced by Cargico Engineering Corp. to study the influence of antimicrobes substratum to the usual seen pathogens in water.
The antibacterial substrata coated with quaternary ammonium salt (QAS) showed no inhibitory effect on Escherichia coli O157 and Pseudomonas aeruginosa, but showed evidently inhibitory effect on Listeria monocytogenes, Staphylococcus aureus, Streptococcus faecalis, and Shigella dysenteriae. The sensitive bacteria had their aerobic plate count (APC) decreased from 7.0 to below 2.3 log CFU/mL in 24 hours. The most sensitive bacteria in this study is Staph. aureus, because that its APC could be lowered down 5.0 log CFU/mL in 1 hour.
The inhibitory effect of carborundum coated with 1.0 wt% quaternary ammonium salt is more efficiently than honeycombs ceramic had same coating treatment. The different range of APC between these two QAS coated substrata is about 1.0-4.0 log CFU/mL depending on test bacterial strains. The result of this study showed the inhibitory effect of carborundum coated with 1.0 wt% QAS is more efficiently than the 0.2 wt% QAS coated carborundum had (about 1.0-2.0 log CFU/mL). The streaming reacting mode could show more efficiently inhibitory effect. As every 20 g carborundum is added to the reacting solution, the survivors would decrease about 1.0-2.0 log CFU/mL in each time. The immobilized QAS antibacterial substrata would show higher inhibitory effect as pH value of the reacting mixture rise to pH 8.0.
The antibacterial substrata used in this study coated with silver ions (1.0 wt%) would showed different inhibitory effect while coating with different carriers, under different operational conditions, the amount of carborundum added for testing were varied, and the value of pH in testing medium was changed. It showed the APC of survivors of L. monocytogenes, P. aeruginosa, Staph. aureus, and Strept. faecalis were lowered from 7.0 to below 2.3 log CFU/mL in 8 hours, but the APC of survivors of E. coli O157 and S. dysenteriae were only degraded to 5.0 log CFU/mL.
The inhibitory effect of carborundum coated with 1.0 wt% silver ions is stronger than honeycombs ceramic with same coating treatment did. The different range on the APC of these two experiments is about 1.0-3.0 log CFU/mL. The streaming reacting mode showed higher inhibitory effect than the other two reacting modes, unmoved and shaking. The former has decreasing the APC of the testing bacteria to the amount lower than the two less efficient reacting modes approximately 0.5-1.5 log CFU/mL. As the amount of carborundum used in the testing would increase 20 g every time, the survivors of testing bacteria would decrease on the APC about 0.5-2.0 log CFU/mL. The immobilized silver ion antibacterial substrata would show higher inhibitory effect as pH value of the reacting solution rise to pH 8.0.
While the dissociation degrees of QAS and silver ions from the antibacterial substrata in aqueous solution were examined, the amount of QAS and silver ions released was below 0.2 and 1.0 ppm. These results indicated that the amount of dissociation of the QAS and silver ions from antibacterial substrata in water are trace.
The results observed under SEM showed cellular morphologies of tested bacteria with few change when adsorbed to carborundum coated with 1.0 wt% QAS (QA-S-2). Although the cellular morphologies of tested bacteria changed significantly while adsorbed to carborundum coated with 1.0 wt% silver ions (Ag-S).
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