<i>Oscillospira</i> and related bacteria – From metagenomic species to metabolic features

TLDR

Oscillospira, an anaerobic Clostridial cluster IV genus, has been detected in human gut microbiota and linked to leanness, yet its metabolism and physiology remain largely unknown. This study aimed to characterize Oscillospira and related bacteria by reconstructing nearly complete genomes from human gut shotgun metagenomic data. The authors employed sequence similarity, gene neighbourhood analysis, and manual metabolic pathway curation to identify key metabolic capabilities. They found that Oscillospira species produce butyrate and can metabolize glucuronate, potentially explaining diet‑related fecal abundance differences and reduced presence in inflammatory diseases.

Abstract

Summary Oscillospira is an under‐studied anaerobic bacterial genus from Clostridial cluster IV that has resisted cultivation for over a century since the first time it was observed. In recent years its 16S rRNA gene was identified in several human gut microbiota studies where it was often associated with interesting traits, especially leanness. However, very little is known about its metabolism or physiology. Here we used nearly complete genomes derived from shot‐gun metagenomic data from the human gut to analyze Oscillospira and related bacteria. We used sequence similarity, gene neighbourhood information and manual metabolic pathway curation to decipher key metabolic features of this intriguing bacterial genus. We infer that Oscillospira species are butyrate producers, and at least some of them have the ability to utilize glucuronate, a common animal‐derived sugar that is both produced by the human host and consumed by that host in diets rich in animal products. These findings could help explain diet‐related inter‐individual variation in faecal Oscillospira levels as well as the observation that the presence of this genus is reduced in diseases that involve inflammation.