Nearly (?) sterile avian egg in a passerine bird

0582395 - ÚBO 2025 RIV US eng J - Journal Article
Těšický, Martin - Schmiedová, Lucie - Krajzingrová, T. - Samblas, M. G. - Bauerová, P. - Kreisinger, J. - Vinkler, M.
Nearly (?) sterile avian egg in a passerine bird.
FEMS Microbiology Ecology. Roč. 100, č. 1 (2024), č. článku fiad164. ISSN 0168-6496. E-ISSN 1574-6941
Institutional support: RVO:68081766
Keywords : egg microbiome * embryo * gastrointestinal tract microbiota * passerine bird * pathogenic bacteria * sterile egg
OECD category: Zoology
Impact factor: 4.2, year: 2022
Method of publishing: Open access
https://academic.oup.com/femsec/article/100/1/fiad164/7480268?login=true

During early ontogeny, microbiome affects development of the gastrointestinal tract, immunity, and survival in vertebrates. Bird eggs are thought to be (1) initially sterile (sterile egg hypothesis) and (2) colonized after oviposition through horizontal trans-shell migration, or (3) initially seeded with bacteria by vertical transfer from mother oviduct. To date, however, little empirical data illuminate the contribution of these mechanisms to gut microbiota formation in avian embryos. We investigated microbiome of the egg content (day 0, E0-egg), embryonic gut at day 13 (E13) and female faeces in a free-living passerine, the great tit (Parus major), using a methodologically advanced procedure combining 16S rRNA gene sequencing and microbe-specific qPCR assays. Our metabarcoding revealed that the avian egg is (nearly) sterile, but acquires a slightly richer microbiome during the embryonic development. Of the three potentially pathogenic bacteria targeted by qPCR, only Dietzia was found in E0-egg (yet also in negative controls), E13 gut and female samples, which might indicate possible vertical transfer. Unlike in poultry, we have shown that major bacterial colonization of the gut in passerines does not occur before hatching. We emphasize that protocols that carefully check for environmental contamination are critical in studies with low-bacterial biomass samples.
Permanent Link: https://hdl.handle.net/11104/0350836