Antimicrobial activity of cuticle and outer eggshell protein extracts from three species of domestic birds

Abstract

1. The eggshell cuticle is the proteinaceous outermost layer of the eggshell which regulates water exchange and protects against entry of micro-organisms. In this study, we investigated the hypothesis that the cuticle may also reduce microbial contamination by providing a chemical defence. 2. Outer eggshell and cuticle protein was extracted from domestic chicken (Gallus gallus), duck (Anas platyrhynchos) and goose (Anser anser) eggs by HCl and urea treatment, respectively. Antimicrobial activity of the extracts against Gram-positive and Gram-negative bacteria was evaluated. 3. C-type lysozyme, ovotransferrin and ovocalyxin-32 were identified in all extracts by Western blotting. All extracts from all species demonstrated lysozyme enzymatic activity. Immobilised c-type lysozyme retained some enzymatic activity. Protein extracts demonstrated activity against Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis suggesting the action of antimicrobial proteins in addition to lysozyme. 4. The results suggest that the antimicrobial outer eggshell and cuticle proteins present in a number of avian species may be a mechanism which enhances avian reproductive success.

Extended-Spectrum-Beta-Lactamase- and Plasmid-Encoded Cephamycinase-Producing Enterobacteria in the Broiler Hatchery as a Potential Mode of Pseudo-Vertical Transmission

“…Eggshell and eggshell membranes are natural defense barriers, but penetration through and multiplication within the egg were shown for salmonellae in various studies (35)(36)(37)(38)(39). To our knowledge, this was also not yet demonstrated for E. coli.…”

“…To our knowledge, this was also not yet demonstrated for E. coli. Penetration of pathogens through the eggshell occurs more likely in cases of incomplete cuticle or with variations in pH, temperature, humidity, or vapor (35,38). In the investigated hatchery, the conditions at our samplings were constant and, therefore, preventive for the penetration of bacteria into the eggs.…”

Protein constituents of the eggshell: eggshell-specific matrix proteins

“…Ovary and oviduct tissue extracts of the domestic hen were found to show antimicrobial activity against both Gram-positive and Gram-negative bacteria [44]. Moreover, eggshell cuticle protein extracts from a number of domestic and wild bird species demonstrated antimicrobial activity against P. aeruginosa, B. subtilis and S. aureus [45,46]. Therefore, antimicrobial activity has been identified in protein extracts from avian eggshell and in particular outer eggshell; however, the identity of specific proteins responsible for the activity remains to be fully elucidated (see next section: ''Eggshell-specific matrix proteins'').…”

Immunolocalization of avian β-defensins in the hen oviduct and their changes in the uterus during eggshell formation

“…Furthermore, if they are secreted to the egg contents during the egg formation, they may participate in the defense of eggs against microorganisms. One of the most important structures of eggs for defense against foreign agents is the eggshell and eggshell membrane that are reported to contain antimicrobial substances (Ahlborn et al 2006, Wellman-Labadie et al 2008. It is hypothesized that those antimicrobial substances are synthesized in the uterus and secreted to be incorporated in the eggshell membrane and eggshell during shell formation.…”