"Anaerotruncus massiliensis," a new species identified from human stool from an obese patient after bariatric surgery.

We report the main characteristics of a new bacterial species strain AT3T (CSUR = P2007, DSM = 100567) that was isolated from the stool sample collected from a 47-year-old obese French man after he underwent bariatric surgery.

We performed an exploratory study of gut microbiota from obese patients before and after bariatric surgery by a microbial culturomics approach, as previously described [1]. 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. The first growth was obtained after 30 days of culture in a blood culture bottle (BACTEC Lytic/10 Anaerobic/F culture vials; Le Pont de Claix, Isère, France) enriched with 4 mL of sheep's blood and 4 mL of rumen under anaerobic atmosphere at 37°C medium. Agar-grown (Columbia agar + 5% sheep's blood; bioMérieux, Marcy l’Etoile, France) colonies were opalescent with a mean diameter of 0.5 to 1.5 mm. The strain AT3T is a bacterial strain, whose spectrum could not be identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) screening on a Microflex spectrometer (Bruker Daltonics, Germany) [2]. The 16S rRNA gene was sequenced using fD1-rP2 primers as previously described [3] using a 3130-XL sequencer (Applied Biosciences, Saint Aubin, France).

Strain AT3T exhibited a 96.6% sequence similarity with Anaerotruncus colihominis strain WAL 14565T = CCUG 45055T = CIP 107754T, the phylogenetically closest species with standing in nomenclature (Fig. 1), which putatively classifies it as a member of the genus Anaerotruncus established in 2004 by Lawson et al. [4] within the Clostridiaceae family in the Firmicutes phylum. Bacterial cells were negative for Gram stain and rod shaped with a size of 0.3 × 2.9 μm. The strain AT3T was catalase positive and oxidase negative. The closest species, Anaerotruncus colihominis, is a Gram-positive bacillus whereas the strain AT3T remained Gram-negative after three assays. Strain AT3T exhibits a 16S rRNA gene sequence divergence higher than 1.35% (3.4%) with its phylogenetically closest species with standing in nomenclature [5]. We propose the creation of a new species called Anaerotruncus massiliensis (ma.si.li.en'.sis, N.L. fem. adj. massiliensis, “of Massilia,” the Latin name of Marseille, where A. massiliensis was first isolated). The strain AT3T is the type strain of the new species A. massiliensis.

Fig. 1

Phylogenetic tree showing position of strain AT3T relative to other phylogenetically closest species. Sequences were aligned using CLUSTALW, and phylogenetic inferences obtained using maximum-likelihood method within MEGA software. Numbers at nodes depict bootstrap values obtained by repeating analysis 500 times to yield consensus tree. Only bootstrap values of at least 90% were retained. Scale bar indicates 1% nucleotide sequence divergence.

MALDI-TOF MS spectrum accession number

The MALDI-TOF MS spectrum of this strain is available at http://www.mediterranee-infection.com/article.php?laref=256&titre=urms-database.

Nucleotide sequence accession number

The 16S rRNA gene sequence was deposited in GenBank as accession number LN_866995.

Deposit in a culture collection

Strain AT3T was deposited in the Collection de Souches de l’Unité des Rickettsies (CSUR) and Deutsche Sammlung von Mikroorganismen (DSM) under number CSUR = P2007 and DSM = 100567.