Vinzelj Julia, Nash Kathryn, Jones Adrienne L, Young R Ty, Meili Casey H, Pratt Carrie J, Wang Yan, Elshahed Mostafa S, Youssef Noha H
Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, U.S.A.
Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada.
bioRxiv. 2025 Mar 30:2025.03.28.646006. doi: 10.1101/2025.03.28.646006.
Anaerobic gut fungi (AGF; ) 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 (), herbivorous, flightless, hindgut fermenting members of the class (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 , and a novel genus in the . 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 strain (strain Ost1) was successfully isolated. Transcriptomics-enabled molecular dating analysis suggested a divergence time of ≈ 30 Mya, a time frame in line with current estimates for ostrich evolution. Comparative gene content analysis between strain Ost1 and other 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 ), 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 .
厌氧肠道真菌（AGF）对于食草动物体内植物生物质的降解至关重要。虽然在哺乳动物中已得到广泛研究，但关于它们在非哺乳动物宿主中的存在、多样性和群落结构的信息仍然稀少。在此，我们报告了鸵鸟（鸵鸟是鸟类纲中食草、不会飞且后肠发酵的成员）体内的AGF群落。针对大核糖体亚基（28S rRNA）的D2区域对粪便样本进行的非培养多样性调查显示，其群落具有较低的α多样性且较为单一。该群落主要由可能代表属中的两个新物种以及中的一个新属的序列组成。在源自哺乳动物和乌龟样本的数据集中，与这些新分类单元相关的序列不存在或极其罕见，这表明AGF与宿主之间存在强烈的关联模式。成功分离出一株AGF菌株（菌株Ost1）。基于转录组学的分子年代分析表明，其分化时间约为3000万年前，这一时期与目前对鸵鸟进化的估计相符。对菌株Ost1与来自哺乳动物的其他AGF物种进行的比较基因含量分析显示高度相似。我们的研究结果将AGF动物宿主的范围扩大到包括鸟类纲成员，突出了一个适应鸵鸟消化道的独特AGF群落，并证明与哺乳动物一样，共同进化的系统共生关系（即AGF与其动物宿主的同步进化）在解释目前AGF在中的分布模式方面起着核心作用。
