Antimicrobial activity of chitosan composites against bacterial strains isolated from goat meat and cheese

Chitosan composites based on residual biomass (shrimp shell) and polyvinyl alcohol (PVA) with different concentrations of CuO nanoparticles (NPs) were prepared and tested against bacteria isolated from goat meat and cheese. A casting method was used to prepare composites with 0, 0.05, 0.10, 0.15 and 0.20% CuO in the mixed solution (chitosan + PVA). The CuO NPs were characterized using FTIR spectroscopy and XRD. Additionally, these composites were analyzed by thermogravimetric analysis (TGA). NPs were detected by XRD mainly in the composite with the highest concentration (0.2%). Isolated bacteria from goat meat and milk (15 strains) were used to test the antibacterial properties of the composites, evaluating the effect of CuO NP concentration. All synthesized composites presented antibacterial inhibition against bacteria. However, for some strains of gram-positive and gram-negative bacteria, inhibition was 50% of that observed for the combination of antibiotics, amoxicillin/clavulanic acid (AMC) or trimethoprim/sulfamethoxazole (SXT). Gram-negative bacteria isolated from goat meat were sensitive to PVA composites with CuO NPs. In most of the tested strains, the zone of inhibition increased as the NP concentration in the composite increased.