COMPARATIVE ANTI-MICROBIAL ACTIVITY OF SUSPENSIONS OF POWDERED COMMERCIAL ZINC OXIDE WATER-SUSPENDED ZINC OXIDES' NANOPARTICLE ON WIDE-SPECTRUM GRAM POSITIVE GRAM NEGATIVE BACTERIAL STRAINS

摘要

The antimicrobial activity of zinc oxide nanoparticles on Enterobacter aerogenes was examined. A set ofdifferent concentrations of nanoparticles at 50, 75,100 & 125 μg-ml-1 were tested on gram negativeEnterobacter sp. for their concentration dependent antimicrobial effects. A number of other bacteriaincluding E.coli & B.subtilus were also evaluated against zinc oxide nanoparticles suspension to checktheir growth. The antimicrobial activity was examined by drawing growth curves using spectrophotometer.The antimicrobial activity was further confirmed by disc diffusion method. The increased concentrationsof zinc oxide nanoparticles at μg/ml effectively checked the bacterial growth and increased the inhibitionzone diameter. In the presence of zinc oxide nanoparticles, Enterobacter growth was significantlyreduced while the zinc oxide powder showed lower levels of antimicrobial activity when compared withsame dose levels i.e. 50, 75 & 100 μg/ml. Further studies on a mixture of lower levels of antimicrobialdrugs and zinc oxide nanoparticles formulation are in progress with a view to effectively curtail thecomparatively large dose regimen of the anti-microbial drugs.ZnO nanoparticles were found to exhibit antibacterial activity against E.coli, B. subtilis and Enterobacteraerogenes. The inhibitory effect increases with increase in the concentrations of ZnO nanoparticles. Acomplete inhibition of microbial growth was achieved at the concentration level of 100μgml-1 and higher. Agrowth study of different microbial cultures was performed in the presence of nanoparticles to observetheir effect on the growth profile. This study shows that Zinc nanoparticles have great promise asantimicrobial agent. Concentration and size are two important factors affecting antimicrobial properties ofZnO nanoparticles. The results indicate that ZnO nanoparticles at concentrations higher than 100μgml-1can significantly inhibit the growth of Microbes compared with the control. This antibacterial effect of ZnOnanoparticles observed in this study is consistent with the results recently reported.