Evaluation of different factors affecting antimicrobial properties of chitosan

• Chitosan has amino, plus primary and secondary OH functional groups.
• Antimicrobial effect of chitosan has been investigated in many studies.
• Several mechanisms have been proposed for the antimicrobial activity by chitosan.
• In the application of chitosan, attention should be paid to factors that affect its activity.

Chitosan as one of the natural biopolymers with antimicrobial activities could be a good choice to be applied in many areas including pharmaceuticals, foods, cosmetics, chemicals, agricultural crops, etc. There have been many studies in the literature which show this superb polymer is dependent on many factors to display its antimicrobial properties including the environmental conditions such as pH, type of microorganism, and neighbouring components; and its structural conditions such as molecular weight, degree of deacetylation, derivative form, its concentration, and original source. In this review, after a brief explanation of antimicrobial activity of chitosan and its importance, we will discuss the factors affecting the antimicrobial properties of this biopolymer based on recent studies.