**Abstract**

Chitosan is a collective name used for a group of compounds having various molecular weights, which are produced from chitin by partially or fully deacetylating and is prepared of β 1,4-linked glucosamine, and it is in deacetylated form of chitin acquired from fungi and/or crustaceans. Due its hydrophilic, cationic and biodegradable nature, chitosan has been cared for a biomaterial, medical, pharmaceutical, drug efficiency, textile, agricultural, food additive for preserving, wastewater clarification, plant pesticide agents and in wound healing. As a compound obtained using various methods, the most prominent features of chitosan are attributable to its antimicrobial and antioxidant properties. Among all the antibacterial compounds from crustaceans, chitosan and its derivatives have been widely used for providing the safety of the foods (especially marine based foods) and shelf life extension. This study presents information about antibacterial activity of chitosan, its mode of action against microorganisms, factors affecting its antimicrobial property and its application in food industry and for public health.

**Keywords:** Antimicrobial activity, chitosan, food safety, mode of action, public health
