Robinne, S. | bioRxiv Science

bioRxiv2026

Sarrella massiliensis gen. nov. sp. nov., a new gut genus isolated from the stool of a healthy donor

Strain Marseille-QA0792 (=CSUR QA0792, CECT 31199) was isolated from the feces of a healthy person using the culturomics method. The fecal sample originated from leftover material collected for a fecal microbiota transplantation (FMT) procedure, obtained during a routine screening in accordance with the guidelines of the French National Agency for Medicines and Health Products Safety (ANSM). This strain is Gram-stain-negative, rod-shaped, non-motile, and non-spore-forming. It is strictly anaerobic, with optimal growth at 37{degrees}C. Strain Marseille-QA0792 presented its highest 16S rRNA identity, 96.2%, with ''Merdibacter massiliensis'' strain Marseille-P3254 (not validly published) (accession number LT598590) and ANI similarity of 75.0% with the same species. Among validly published species, strain Marseille-QA0792 showed its highest 16S rRNA gene sequence similarity (91.5%) with Faecalicoccus acidiformans strain 37-2a (accession number HQ452864), whereas all computed average nucleotide identity (ANI) values were below 75%. Genome sequencing revealed a genome size of 2.67 Mb and a G+C content of 50.01%. This species is classified within the Erysipelotrichaceae family in the Bacillota phylum. Thus, we isolated for the first time a novel genus named Sarrella massiliensis gen. nov., sp. nov., strain Marseille-QA0792. This discovery highlights the importance of continuing culturomics efforts to explore the human microbiome.

microbiology↗

bioRxiv2021

Speciation of the Mycobacterium tuberculosis complex using mass spectrometry: a proof-of-concept.

Mycobacteria that form the Mycobacterium tuberculosis complex are responsible for deadly tuberculosis in animals and patients. Identification of these pathogens at the species level is of primary importance for treatment and source tracing, and currently relies on DNA analysis, including whole genome sequencing (WGS), which takes a whole day. In this study, we report on the unprecedented identification of the M. tuberculosis complex species using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS), with WGS as the comparative gold standard. In a first step, an optimised peptide extraction applied to 24 isolates otherwise identified in three of the 11 M. tuberculosis complex species by WGS, yielded 94 MALDI-TOF spectra which clustered according to WGS identification. In a second step, 70/74 (95%) other isolates were correctly identified at the species level by this clustering method. This study is the first to report a MALDI-TOF-MS method of identification of M. tuberculosis complex mycobacteria at the species level and is easily implantable in clinical microbiology laboratories.

microbiology↗