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bioRxiv · 10.1101/2025.03.28.646006

The anaerobic gut fungal community in ostriches (Struthio camelus)

Vinzelj, J.·Nash, K.·Jones, A. L.·Young, R. T.·Meili, C. H.·Pratt, C. J.·Wang, Y.·Elshahed, M. S.·Youssef, N. H.
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Abstract

Anaerobic gut fungi (AGF; Neocallimastigomycota) are essential for plant biomass degradation in herbivores. While extensively studied in mammals, information regarding their occurrence, diversity, and community structure in non-mammalian hosts remains sparse. Here, we report on the AGF community in ostriches (Struthio camelus), herbivorous, flightless, hindgut fermenting members of the class Aves (birds). Culture-independent diversity surveys of fecal samples targeting the D2 region of the large ribosomal subunit (28S rRNA) revealed a uniform community with low alpha diversity. The community was mostly comprised of sequences potentially representing two novel species in the genus Piromyces, and a novel genus in the Neocallimastigomycota. Sequences affiliated with these novel taxa were absent or extremely rare in datasets derived from mammalian and tortoise samples, indicating a strong pattern of AGF-host association. One Piromyces strain (strain Ost1) was successfully isolated. Transcriptomics-enabled molecular dating analysis suggested a divergence time of {approx} 30 Mya, a time frame in line with current estimates for ostrich evolution. Comparative gene content analysis between strain Ost1 and other Piromyces species from mammalian sources revealed a high degree of similarity. Our findings expand the range of AGF animal hosts to include members of the birds (class Aves), highlight a unique AGF community adapted to the ostrich alimentary tract, and demonstrate that - like mammals - coevolutionary phylosymbiosis (i.e. concurrent evolution of AGF and their animal hosts) plays a central role in explaining current AGF distribution patterns in Aves.

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Vinzelj, J., Nash, K., Jones, A. L., Young, R. T., Meili, C. H., Pratt, C. J., Wang, Y., Elshahed, M. S., Youssef, N. H.. 2025-03-30. The anaerobic gut fungal community in ostriches (Struthio camelus). https://doi.org/10.1101/2025.03.28.646006

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