Waterproof layer protects turkey eggs from bacteria

Shells of Australian brush turkeys are 1.5 times thinner than those of chickens, but that does not make them more vulnerable to attacks from microbes because of a natural waterproof layer, a study finds.

The shells are covered in a layer of nanometre-sized spheres of calcium phosphate, which makes them more water-repellent than chicken eggs and helps them to fend off bacterial attachment and penetration.

"The lotus leaf is considered the most hydrophobic material in nature," said Liliana D'Alba, a behavioural ecologist at University of Akron in US.

"These eggshells are pretty close to that, to being super-hydrophobic," D'Alba added.

Australian brush turkeys incubate their eggs in moist piles of rotting vegetation inhabited by microbes and despite the risk, infections occur in only about nine percent of the eggs.

Two bacterial species, Pseudomonas aeruginosa and Escherichia coli, infiltrated chicken shells within 2 to 6 days of contacting their surfaces, but required significantly more time to enter brush-turkey eggshells, found the researchers.

The findings of the research could help develop new antimicrobial coatings for plastics and other surfaces.

The study appeared in the Journal of Experimental Biology.