Study
Monotreme lactation protein is highly expressed in monotreme milk and provides antimicrobial protection
Enjapoori, Ashwantha Kumar; Kukuljan, Sonja; Dwyer, Karen M.; Sharp, Julie A.
Genome Biology and Evolution, 2014
A protein abundant in platypus and echidna milk but absent from other mammals was identified, its gene traced, and its antibacterial activity tested directly against bacterial cultures.
- Studied in
- Ornithorhynchus anatinus, Tachyglossus aculeatus
- Sample size
- milk protein characterisation across monotremes
Monotreme lactation protein is highly expressed in monotreme milk and has direct antibacterial activity. It has no counterpart in other mammals. Monotremes have no nipples: milk is secreted from patches of skin and the young take it from the fur and skin surface.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Monotreme milk carries a lineage-specific antimicrobial protein, consistent with the exposure created by delivering milk across an open skin surface rather than through a teat.
How NatureHQ reads it
This is the answer to a question the popular version never asks. "Platypuses sweat milk" gets repeated as a piece of trivia; the interesting part is what follows from it. Milk pooling on fur and skin, rather than passing through a sealed teat, is an excellent environment for bacteria — and monotreme milk turns out to carry a specific antibacterial protein that no other mammal has. The oddity is not a leftover, it is a system with its own solution attached.
- Antibacterial activity was demonstrated in vitro; its contribution in a suckling animal is inferred.
- Milk sampling from monotremes is difficult, so sample sizes are small.
- Whether the protein evolved before or after the loss of teats is not resolved.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: University press journalsPublished in a university press journal.
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.