Chitin is another natural biopolymer after cellulose. Chitin and its derivative chitosan have been widely applied in agriculture,medicine,food processing,environmental protection and biotechnology due to the important physicochemical properties,admirable biodegradability,biocompatibility,and no toxicity. However,chitin is hard to be dissolved because of the strong hydrogen bond between chitin molecules,which limits its applications. Chitosan can be obtained from chitin by deacetylation,and the interaction force among chitosan molecules weakens due to the decrease of acetyl groups,which improves the solubility to a certain extent. Meanwhile,chitosan demonstrates more important economic value in drug slow-release,wound healing and other medical aspects,as the presence of a large number of free amino groups. In this paper,the traditional chemical method of preparing chitin,i.e.,acid-base method is described briefly;the method still is of many limitations and disadvantages,such as high energy consumption,high cost and serious environmental pollution,even though it is mature. Based on this,the environmental friendly enzymatic and microbial fermentation methods are summarized,their advantages and disadvantages are discussed respectively,the biological preparation methods of its important derivative chitosan are also summarized. The key issues in chitin/chitosan production from laboratory research to industrialization by biological method are analyzed,and finally the research directions of biological preparation methods for chitin/chitosan are further prospected.
