Chitosan as Antimicrobial Agent: Applications and Mode of Action

Chitin is the second most abundant natural biopolymer after cellulose. The chemical structure of chitin is similar to that of cellulose with 2-acetamido-2-deoxy-β- d -glucose (NAG) monomers attached via β(14) linkages. Chitosan is the deacetylated (to varying degrees) form of chitin, which, unlike chitin, is soluble in acidic solutions. Application of chitinous products in foods and pharmaceuticals as well as processing aids has received considerable attention in recent years as exotic synthetic compounds are losing their appeal. This review summarizes some of the important developments related to food applications of chitin, chitosan and their derivatives.

Food applications of chitin and chitosans

The antibacterial action of chitosan hydroglutamate (CH), chitosan lactate (CL) and chitosan derived from fungal mycelia was examined against both gram‐negative and gram‐positive bacteria. Plate counts indicated inactivation rates of one‐ to five‐log‐cycles within one hour. Fungal chitosan had significantly less antibiotic effect than CH and CL. The antibacterial action of CH and CL was very similar and shown to be concentration dependent with 0.1 mg/mL more effective than 2.0 and 5.0 mg/mL. When CH (or CL) and polygalacturonate were added to cell suspensions, death was prevented, possibly indicating that chitosan complexed with polygalacturonate could not penetrate the cell or disrupt the membrane. Leakage of intracellular components caused by chitosan was determined by exposing lactose‐induced Escherichia coli to chitosan with assay for s‐galactosidase activity indicating that cell permeabilization occurred more extensively at the low chitosan concentrations. Microscopic examination showed that...

Antibacterial action of chitosan

Chitosan: antimicrobial activity, interactions with food components and applicability as a coating on fruit and vegetables

Chitosan is a modified, natural biopolymer derived by deacetylation of chitin, a major component of the shells of crustacean. Recently, chitosan has received increased attention for its commercial applications in the biomedical, food, and chemical industries. Use of chitosan in food industry is readily seen due to its several distinctive biological activities and functional properties. The antimicrobial activity and film-forming property of chitosan make it a potential source of food preservative or coating material of natural origin. This review focuses on the applications of chitosan for improvement of quality and shelf life of various foods from agriculture, poultry, and seafood origin.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1750-3841.2007.00383.x

Applications of Chitosan for Improvement of Quality and Shelf Life of Foods: A Review

The regulatory role of chitosan in eucaryotic organisms may have far reaching consequences because chitosan and its acetylated form, chitin, are prevalent in nature. We have found two different regulatory functions for chitosan in a simple fungal-plant interaction1. Chitosan which is a normal component of the cell walls of some fungi (Fig. 1) can activate specific genes in plants and at similar concentrations can completely inhibit all RNA synthesis in some fungal organisms and thus suppress gene activity. In this paper we review data which partially explains this paradoxical action.

Chitosan Both Activates Genes in Plants and Inhibits RNA Synthesis in Fungi

Many of the disease resistance traits in plants can be transferred within the species using conventional cross-breeding techniques. These specific traits are often inherited as single mendelian genes and often occur as alleles at a given locus, suggesting that a single enzyme or protein product is associated with each gene. We have proposed that the “gene for gene” interaction associated with a given disease reaction involves the interaction of a product (inducer) coded by an avirulence gene in the pathogen with a resistance gene associated with a host response [1,2].

Pea Genes Associated with the Non-Host Resistance to Fusarium Solani are also Induced by Chitosan and in Race-Specific Resistance by Pseudomonas Syringae

D. F. Kendra

Papers

Chitosan Both Activates Genes in Plants and Inhibits RNA Synthesis in Fungi

Pea Genes Associated with the Non-Host Resistance to Fusarium Solani are also Induced by Chitosan and in Race-Specific Resistance by Pseudomonas Syringae