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We report here the main phenotypic characteristics of “Bariatricus massiliensis” strain AT12 (CSUR P2179), isolated from the stool of a 58-year-old woman who underwent bariatric surgery.
In 2015, as part of our culturomics project aiming at identifying all bacterial species within the human microbiota , , we analysed a stool specimen from a 58-year-old-woman who benefitted from bariatric surgery for obesity, with a body mass index of 36.65 kg/m2 before surgery. The patient provided signed informed consent, and the study was validated by the ethics committee of the Institut Federatif de Recherche IFR48 under number 09-022.
We isolated the strictly anaerobic strain AT12, which could not be identified by matrix-assisted desorption ionization–time of flight mass spectrometry (MALDI-TOF MS; Microflex; Bruker Daltonics, Leipzig, Germany) . The MALDI-TOF MS spectra are available in our database (http://www.mediterraneeinfection.com/article.php?laref=256&titre=urms-database). The initial growth was obtained in anaerobic conditions at 37°C after 10 days of culture on 5% sheep blood–enriched Columbia agar (bioMérieux, Marcy l’Etoile, France). Agar-grown colonies were greyish and ranged in diameter from 0.5 to 1.5 mm. Strain AT12 is a rod-shaped and polymorphic Gram-positive bacillus, ranging in length from 1.25 to 2.5 μm. Strain AT12 is catalase and oxidase negative. The complete 16S rRNA gene was sequenced using a 3130-XL sequencer (Applied Biotechnologies, Villebon sur Yvette, France). Strain AT12 exhibited a sequence identity of 94.37% with Clostridium nexile strain ATCC 27757 (GenBank accession no. X73443), its closest phylogenetic neighbour with a validly published name (Fig. 1). This putatively classified strain AT12 within a new genus within the order Clostridiales.
Clostridium nexile strain ATCC 27757 is a strictly anaerobic Gram-positive bacterium initially detected in human faeces in 1974. It was later isolated again from the faecal flora of 20 healthy Japanese Hawaiians . In addition, it has been shown that Clostridium nexile possesses a gene encoding a trypsin-dependent lantibiotic ruminococcin A (RumA) . This protein may be an effective bacteriocin against Clostridium perfringens .
Another bacterium closely related to “B. massiliensis” strain AT12 is Lactonifactor longoviformis, another member of the order Clostridiales. It was isolated for the first time in 2007 from a fresh stool sample from a healthy man. The first isolate was a strictly anaerobic Gram-positive, helically coiled rod .
Because of a 16S rRNA difference greater than 5% with its closest phylogenetic neighbour , we propose that strain AT12 is the representative strain of a new genus with the order Clostridiales, for which we propose the name “Bariatricus” gen. nov. after bariatrics, the medical specialty that deals with the causes, prevention and treatment of obesity. Strain AT12T is the type species of “Bariatricus massiliensis” sp. nov.
The 16S RNA gene sequence was deposited in GenBank under accession number LN898273.
Strain AT12T was deposited in the Collection de Souches de l’Unité des Rickettsies (CSUR; WDCM 875) under number P2179.
This study was funded by the Fondation Méditerranée Infection.