XRD analysis and antibacterial activity of Chitosan from Archachatina marginata shells: a novel approach to sustainable antimicrobial materials

The increasing demand for sustainable antimicrobial materials and the environmental burden of crustacean shell waste necessitate exploration of alternative chitosan sources with comparable bioactivity and superior cost-effectiveness. This proof-of-concept study investigates chitosan extraction from shells of Archachatina marginata, presenting a green chemistry approach to waste valorization. Sequential alkali deproteinization, acid demineralization, and alkaline deacetylation yielded 12.3% chitosan from dry shell weight. X-ray diffraction analysis revealed optimal crystallinity (65–70%) with well-ordered crystalline domains, while FTIR spectroscopy confirmed successful deacetylation (75.39%) with diagnostic bands indicating free amino group availability for antimicrobial action. Antimicrobial evaluation using disk diffusion and broth microdilution assays against five bacterial pathogens demonstrated significant activity against Staphylococcus saprophyticus (39.00 ± 1.00 mm zone of inhibition), S. aureus (34.67 ± 0.58 mm), Klebsiella pneumoniae (26.67 ± 0.58 mm), and Escherichia coli (23.67 ± 0.58 mm), with minimum inhibitory concentrations ranging from 0.0781 to 0.3125 mg/mL for susceptible strains. Notably, Salmonella typhi exhibited complete resistance (MIC > 40.0 mg/mL), representing a unique selectivity pattern not previously documented for alternative chitosan sources and highlighting organism-specific resistance mechanisms. The natural chitosan-CaCO₃ biocomposite structure offers potential synergistic properties for applications beyond antimicrobial uses. Literature-based economic extrapolations suggest potential 54–58% production cost reduction compared to crustacean sources, driven by zero-cost feedstock acquisition and year-round availability. Environmental metrics derived from comparative analysis indicate potential 35–47% energy savings and 42–61% carbon footprint reduction. These findings position A. marginata shell-derived chitosan as a promising sustainable alternative warranting further investigation for food preservation, biomedical devices, water treatment, and biodegradable packaging applications, contributing to circular economy waste valorization strategies while addressing global sustainability challenges.