Introducing clinical nanoarchaeaology: Isolation by co-culture of Nanopusillus massiliensis sp. nov.

BACKGROUND: Nanoarchaeota, obligate symbiont of some environmental archaea with reduced genomes, have been described in marine thermal vent environments, yet never detected in hosts, including humans. METHODS: Here, using laboratory tools geared towards the detection of nanoarchaea including PCR-sequencing, WGS, microscopy and culture. RESULTS: We discovered a novel nanoarchaea, Nanopusillus massiliensis, detected in dental plate samples by specific PCR-based assays. Combining fluorescent in situ hybridization (FISH) with scanning electron microscopy disclosed close contacts between N. massiliensis and the archaea Methanobrevibacter oralis in these samples. Culturing one sample yielded co-isolation of M. oralis and N. massiliensis with a 606,935-bp genome, with 23.6% GC encoded 16 tRNA, 3 rRNA and 942 coding DNA sequences, of which 400 were assigned to clusters of orthologous groups. CONCLUSION: The discovery of N. massiliensis, made publicly available in collection, extended our knowledge of human microbiota diversity, opening a new field of research in clinical microbiology here referred to as clinical nanoarchaeology.