Structure and Antibacterial Activity of Chitosan from the American Cockroach, the German Cockroach and the Mealworm Beetle

Owing to chitosan properties such as biocompatibility and antimicrobial activities, and several applications in biomedical field, some physicochemical and anti-bacterial properties, and the level of chitosan from three species of American cockroach, Periplaneta americana (Dictyoptera: Blattidae), the German cockroach, Blattella germanica (Dictyoptera: Ectobiidae) and the Mealworm beetle, Tenebrio molitor (Coleoptera: Tenebrionidae) were investigated.

The cuticle of adults derived from specimens was dried and grounded. The powders were demineralized as well as deproteinized after deacetylation via NaOH. At last, the chitosan yields from insects were studied for anti-bacterial activity on Gram-positive bacteria (Proteus mirabilis, Klebsiella pneumoniae), and Gram-negative bacteria (Enterococcus faecalis and Staphylococcus epidermidis). The Fourier transform infrared spectroscopy (FTIR) was used to analyze the chitosan composition.

The chitosan ratios of the American and German cockroaches and the mealworm beetle were 5.80, 2.95, and 1.70% per 3 g of the dried bodies respectively. The chitin DD’s for the American cockroach, the German cockroach and the mealworm beetle were 36.8%, 31.5% and 27.3%, respectively. The bactericidal activity of chitosan obtained from the American cockroach at a concentration of 1% had the greatest effect on P. mirabilis compared to other concentrations, while chitosan obtained from the German cockroach at a concentration of 0.01% had the greatest effect on K. pneumoniae compared to other concentrations.

According to the results, the anti-bacterial influence of the chitosan is based upon the insect species and chitosan concentration. Probably, the variation relates to the changes in the chitin structure among the three insect species.