In this present study, various concentrations (0.5, 1, and 2%) of chitosan extracted through the chemical methods from the shells of crayfish (Astacus leptodactylus), pink shrimp (Parapenaeus longirostris), blue crab (Callinectes sapidus) shells, methanolic extracts of black cumin (Nigella sativa L), flaxseed (Linum usitatissimum), Chaste Tree (Vitex agnus-castus L.) and black cumin and flaxseed oil were tested in vitro for their antibacterial activities against two pathogenic bacteria Escherichia coli and Staphylococcus aureus, using the disk diffusion method.