Raimondi Stefano, Amaretti Alberto, Gozzoli Caterina, Simone Marta, Righini Lucia, Candeliere Francesco, Brun Paola, Ardizzoni Andrea, Colombari Bruna, Paulone Simona, Castagliuolo Ignazio, Cavalieri Duccio, Blasi Elisabetta, Rossi Maddalena, Peppoloni Samuele
Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
Department of Molecular Medicine, University of Padua, Padua, Italy.
Front Microbiol. 2019 Jul 10;10:1575. doi: 10.3389/fmicb.2019.01575. eCollection 2019.
The fungal component of the intestinal microbiota of eight healthy subjects was studied over 12 months using metagenome survey and culture-based approaches. , , , , , , and were the most recurrent and/or dominant fungal genera, according to metagenomic analysis. The biodiversity of fungal communities was lower and characterized by greater unevenness, when compared to bacterial microbiome. The dissimilarities both among subjects and over the time within the same subject suggested that most of the fungi passed through the gastro-intestinal tract (GIT) without becoming stable colonizers. Certain genera, such as and , were isolated in a minority of cases, although they recurred abundantly and frequently in the metagenomics survey, likely being environmental or food-borne fungi that do not inhabit the GIT. genus was recurrently detected. isolates dominated among the cultivable mycobiota and longitudinally persisted, likely as commensals inhabiting the intestine or regularly reaching it from -colonized districts, such as the oral cavity. Other putative colonizers belonged to , , and , with persisting biotypes being identified. Phenotyping of fungal isolates indicated that adhered to human epithelial cells more efficiently and produced greater amounts of biofilm than non- (NAC) and non- fungi (NCF). The isolates also induced the highest release of HBD-2 by human epithelial cells, further differing from NAC and NCF. Nine representative isolates were administered to mice to evaluate the ability to colonize the intestine. Only two out of three strains persisted in stools of animals 2 weeks after the end of the oral administration, whereas NAC and NCF did not. These results confirm the allochthonous nature of most the intestinal fungi, while appears to be commonly involved in stable colonization. A combination of specific genetic features in the microbe and in the host likely allow colonization from fungi normally present solely as passengers. It remains to be established if other species identified as potential colonizers, in addition to , are true inhabitants of the GIT or rather reach the intestine spreading from other body districts.
采用宏基因组调查和基于培养的方法，对8名健康受试者肠道微生物群的真菌成分进行了为期12个月的研究。根据宏基因组分析，曲霉属、念珠菌属、酿酒酵母属、马拉色菌属、隐球菌属、毛孢子菌属和枝孢菌属是最常见和/或占主导地位的真菌属。与细菌微生物组相比，真菌群落的生物多样性较低，且特征为不均匀性更大。受试者之间以及同一受试者在不同时间的差异表明，大多数真菌通过胃肠道（GIT）而未成为稳定的定植菌。某些属，如枝孢菌属和隐球菌属，在少数情况下被分离出来，尽管它们在宏基因组学调查中大量且频繁地出现，可能是不栖息在GIT中的环境或食源真菌。马拉色菌属被反复检测到。白色念珠菌分离株在可培养的真菌菌群中占主导地位并纵向持续存在，可能作为共生菌栖息在肠道中，或定期从口腔等定殖区域到达肠道。其他假定的定植菌属于曲霉属、毛孢子菌属和酿酒酵母属，并鉴定出了持续存在的生物型。真菌分离株的表型分析表明，白色念珠菌比非白色念珠菌（NAC）和非念珠菌真菌（NCF）更有效地粘附于人类上皮细胞，并产生更多的生物膜。白色念珠菌分离株还诱导人类上皮细胞释放最高水平的HBD-2，这进一步不同于NAC和NCF。将9株代表性分离株接种到小鼠体内，以评估其在肠道定植的能力。口服给药结束2周后，在动物粪便中仅检测到三株白色念珠菌菌株中的两株，而NAC和NCF未被检测到。这些结果证实了大多数肠道真菌的外来性质，而白色念珠菌似乎通常参与稳定定植。微生物和宿主中的特定遗传特征组合可能使通常仅作为过客存在的真菌得以定植。除白色念珠菌外，其他被鉴定为潜在定植菌的物种是否是GIT的真正居民，还是从身体其他部位扩散到肠道，仍有待确定。
