Synergistic Antimicrobial Effects of Zeolite and Eggshell Against Salmonella Typhimurium and Listeria monocytogenes

Turkey is one of the world's leading egg producers, yet eggshells are usually thrown away as waste and not recycled. However, recycling these materials could benefit both the environment and the economy significantly. In poultry farming, bedding material is of critical importance for animal health, with natural, hygienic, inexpensive and environmentally friendly materials being preferred. In this study, the antimicrobial effects of bedding materials obtained by mixing eggshells with zeolite at specific ratios were investigated on Salmonella Typhimurium and Listeria monocytogenes. Mixtures prepared at ratios of 100% eggshell, 100% zeolite, 75% eggshell + 25% zeolite, and 50% eggshell + 50% zeolite were inoculated with these pathogens and analysed at 0, 6, 12, 24, and 48 hours. The most effective reduction was observed in the 50% eggshell + 50% zeolite mixture for S. Typhimurium at 12 hours [1.4 log₁₀ (p<0.05)] and in the 50% eggshell + 50% zeolite mixture for L. monocytogenes at 6 and 12 hours [1 log₁₀ (p<0.05)]. The moisture-absorbing and toxin-binding properties of zeolite, in synergy with eggshell, were effective in reducing the microbial load. These findings suggest that eggshell can be transformed into an effective bedding material when used in combination with zeolite. This study contributes to the development of alternative bedding materials in the poultry industry while providing a meaningful contribution to the literature in terms of re-evaluating waste-based biomaterials.