Antibacterial activity of chitosan and zinc oxide nano-particle incorporated chitosan in different organic solvents

Abstract

Chitosan is usually dissolved in mild organic acids for various applications. Most of the previous experiments were carried out using acetic acid as a solvent for chitosan solution preparation. But, limited studies are available regarding antimicrobial properties of chitosan in different organic acids. The present study was carried out to understand the effect of different organic acids viz., propionic, lactic, citric, malic, oxalic, acetic, tartaric and benzoic acid on the antimicrobial properties of chitosan. Recently, enhanced antimicrobial activity of chitosan by incorporation of zinc oxide nanoparticles is gaining interest. Hence, in the present study, in addition to chitosan, antimicrobial property of zinc oxide nanoparticle incorporated chitosan in various acids was also comprehended. The biological activity was measured based on well diffusion assay against various food borne and multi drug resistant pathogens such as E. coli Salmonella, V. cholera, L. monocytogenes, S. aureus, B. cereus, B. subtilis, methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa. The results indicated varying degrees of antimicrobial activity for chitosan and ZnO-NP-CH in different acids. ZnO-NP-CH exhibited better antimicrobial activity than chitosan alone i.e., around 10 -15 mm wider zone of inhibition. Most of the bacteria resistant to chitosan became susceptible after incorporation of ZnO-NP. Among eight organic acids studied, propionic and acetic acid were found more suitable for chitosan with better antimicrobial activity. The order for the antimicrobial activity was as follows: Propionic greater than Acetic greater than Malic greater than Citric greater than Oxalic greater than Lactic greater than Tartataric greater than Benzoic acid.