Dubourg, G. | Search bioRxiv

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↗

bioRxiv2019

Antioxidants maintain Butyrate production by Human Gut Clostridia in the presence of Oxygen

BackgroundOxygen diffused from the human gut mucosa and shape the microbiota with a radial gradient of microbes according to their oxygen tolerance, while microbial and chemical oxygen consumption maintains the lumen in a deeply anaerobic state. Uncontrolled oxidative stress and hyperoxygenation have been reported as a pathogenic mechanism in Salmonella or Citrobacter rodentium infection, in patients with HIV and in severe acute malnutrition. We recently found that antioxidants allow strict anaerobes, including methanogenic archaea, to thrive in an oxidative environment (aerobic). Here, we tested the metabolomics switching of the 3 most odorous anaerobic microbes isolated from human gut when grown in aerobiosis with antioxidants.\n\nMethodsThree human gut Clostridia, Clostridium sporogenes, Clostridium lituseburense and Clostridium subterminale, isolated by culturomics, were grown in anaerobiosis or in aerobiosis with antioxidants. Gaz and liquid chromatography-Mass spectrometry (GC/MS and LC/MS) were used for metabolomics analysis.\n\nResultsAn unexpected global dichotomic metabolomic switching from thiols, alcohols and short-chain fatty acid esters to a specific aerobic metabolic repertoire with the production of alkanes, cycloheptatriene and, paradoxically, increased butyrate production, was observed. Analysis of polar metabolites confirmed the discovery of an unexplored aerobic metabolic repertoire, including the production of specific dipeptides and several lysophospholipids, thus unraveling unsuspected human gut microbiome capacities.\n\nConclusionsAntioxidants unraveled an unexplored aerobic metabolic repertoire of human gut Clostridia. The increased production of butyrate suggests that antioxidants contribute to the maintenance and the active resilience of the human gut microbiome against oxidative aggression, as during Salmonella infection.

microbiology↗