Comparative in- vitro studies on antimicrobial activity of bulk and nanozinc oxide incorporated chitosan

Abstract

NnO-Nano particle is known for its antimicrobial property but as it is not food grade, it has limitations in seafood application. However, ZnO-Bulk particle is a GRAS (Generally Recognized As Safe) listed substance and hence can be added in the food as a supplement (CFRNo.182.8991). However, no previous literature is available on the antimicrobial property exhibited by ZnO-BP. Hence, the present study was carried out to exploit the antimicrobial activity of ZnO-BP incorporated chitosan and its comparison with ZnO-NP incorporated chitosan. ZnO-NP was prepared by Solgel method and the size was confirmed by the UV-Visible spectrometer and scanning electron microscope. The activity of the BP and NP was assessed by minimum inhibitory concentration and minimum bactericidal concentration. Similarly, the activity of the ZnO-NP incorporated chitosan and ZnO-BP incorporated chitosan was assessed by antibiogram with various food borne pathogenic and specific spoilage organisms in fish. The results indicated that ZnO-BP-CH was equally effective to ZnO-NP-CH against most of the bacteria. Both ZnO-BP-CH and ZnO-NP-CH exhibited higher inhibition zone i.e., 10 - 15 mm than chitosan alone. Among the SSOs, Pseudomonas was found highly susceptible. The order of susceptibility of the SSOS against ZnO-BP-CH and ZnO-NP-CH were as follows: Pseudomonas greater than H2S formers greater than Mould greater than B. thermosphacta greater than Lactobacillus greater than Yeast. Hence, the present study concluded that ZnO-BP-CH can be used as a suitable antimicrobial agent in seafoods for their shelf stability.