To provide methods and compositions for increasing the microbiota diversity and/or inducing stability of the microbiota of a subject.SOLUTION: Provided are specific compositions comprising a bacterial strain of the genus Blautia, where the bacterial strain has a 16s rRNA sequence that is at least 97%, 98%, 99%, 99.5% or 99.9% identical to the 16s rRNA sequence of a bacterial strain of Blautia hydrogenotrophica.SELECTED DRAWING: None【課題】対象の微生物叢多様性を増加させる及び/または微生物叢の安定性を誘導する方法および該組成物の提供。【解決手段】Blautia属の細菌株を含む組成物であり、該細菌株が、Blautia hydrogenotrophicaの細菌株の16s rRNA配列と少なくとも97%、98%、99%、99.5%または99.9%同一の16s rRNA配列を有する特定の組成物。【選択図】なし