Objectives: Methanogenic Archaea are considered as extremely oxygen-sensitive organisms, and their culture is fastidious, requiring specific equipment. We report here conditions allowing the cultivation of Methanobrevibacter smithii in an anaerobic chamber without the addition of hydrogen. Methods: We first enriched the stool sample in an anaerobic liquid medium. To cultivate M. smithii with Bacteroides thetaiotaomicron and other hydrogen-producing bacteria on solid medium in an anaerobic chamber, we divided the agar plates into two compartments and seeded each strain on each compartment. Methane production was assessed by gas chromatography, and the growing colonies were authenticated by MALDI-TOF MS. Results: We successfully cultured M. smithii from a liquid culture medium inoculated with stool collected from a healthy donor in an anaerobic chamber. The isolation in pure culture permitted successful culture on agar medium by our performing a co-culture with B. thetaiotaomicron. We also successfully tested the co-cultivation of M. smithii with other known hydrogen-producing bacteria. Gas chromatographic tests showed that these strains produced hydrogen in different amounts. Agar colonies of methanogens were obtained by co-culture with these bacteria, and methane production was detected. Conclusions: We propose a new approach to isolate and cultivate new strains of M. smithii by using a cocultureebased technique that can facilitate and make available the isolation of new methanogenic Archaea strains in clinical microbiology laboratories.

We report here the main characteristics of ‘Blautia phocaeensis’ strain Marseille-P3441 sp. nov. and ‘Lachnoclostridium edouardi’ strain Marseille-P3397 sp. nov., that were isolated from a faecal specimen of a 42-year-old female Saudi Bedouin. We used a bacterial culturomics approach combined with taxono-genomics.

We propose the description of a new bacterial genus and new bacterial species, “Raoultibacter massiliensis,” isolated from a faecal specimen of a 19-year-old healthy Saudi Bedouin.