Reclassification of eight Akkermansia muciniphila strains and description of Akkermansia massiliensis sp. nov. and Candidatus Akkermansia timonensis, isolated from human feces.

Akkermansia muciniphila is a human intestinal tract bacterium that plays an important role in the mucus layer renewal. Several studies have demonstrated that it is a modulator for gut homeostasis and a probiotic for human health. The Akkermansia genus contains two species with standing in nomenclature but their genomic diversity remains unclear. In this study, eight new Akkermansia sp. strains were isolated from the human gut. Using the digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI) and core genome-based phylogenetic analysis applied to 104 A. muciniphila whole genomes sequences, strains were reclassified into three clusters. Cluster I groups A. muciniphila strains (including strain ATCC BAA-835T as type strain), whereas clusters II and III represent two new species. A member of cluster II, strain Marseille-P6666 differed from A. muciniphila strain ATCC BAA-835T and from A. glycaniphila strain PytT in its ability to grow in microaerophilic atmosphere up to 42 °C, to assimilate various carbon sources and to produce acids from a several compounds. The major fatty acids of strain Marseille-P6666 were 12-methyl-tetradecanoic and pentadecanoic acids. The DNA G + C content of strain Marseille-P6666 was 57.8%. On the basis of these properties, we propose the name A. massiliensis sp. nov. for members of cluster II, with strain Marseille-P6666T (= CSUR P6666 = CECT 30548) as type strain. We also propose the name "Candidatus Akkermansia timonensis" sp. nov. for the members of cluster III, which contains only uncultivated strains, strain Akk0196 being the type strain.

Ottowia massiliensis sp. nov., a new bacterium isolated from a fresh, healthy human fecal sample.

The culturomics method enabled isolation of a new member of the Ottowia genus from the stool sample of a healthy volunteer. Strain Marseille-P4747T exhibited a 96.18% 16S rRNA sequence identity with Ottowia beijingensis strain GCS-AN-3 (NR_133803.1), the closest species with standing in nomenclature. It is a Gram-stain-negative, nonmotile, and aerobic bacterium. It does not possess catalase and oxidase activities. Its genome has a size of 2 830 447 bp and a G + C content of 63.5 mol%. Based on the phylogenic, phenotypic, and genomic analyses, we conclude that Ottowia massiliensis sp. nov. is a new species, represented by Marseille-P4747T ( = CSUR P4747 = CECT 30348) as type strain.

Neglectibacter timonensis gen. nov., sp. nov. and Scatolibacter rhodanostii gen. nov., sp. nov., two anaerobic bacteria isolated from human stool samples.

Strains Marseille-P2265T (=CSUR P2265T =DSM 102082 T) and Marseille-P3890T (=CSUR P3890T =CCUG 72341 T) were isolated from stool samples using the culturomics approach. The 16S rRNA gene sequences of both strains were sequenced and compared by BLASTn to the NCBI database. Strains Marseille-P2265T and Marseille-P3890T were most closely related to Acutalibacter muris with identities of 94.3% and 91.5%, respectively. Between the two strains, the 16S rRNA gene sequence identity was 91.5%. Both strains are anaerobic Gram-positive, oxidase- and catalase-negative. The major fatty acid methyl esters (> 10%) in both strains are C16:0 and anteiso-C15:0. Additionally, strain Marseille-P2265T has iso-C15:0 and C14:0, and strain Marseille-P3890T, iso-C14:0. Strain Marseille-P2265T has a genome size of 3,671,396-bp with a G + C content of 52.8%. As for strain Marseille-P3890T, the genome is 2,702,024-bp-long with a 39.8% G + C content. The genomic comparison of closely related species with strains Marseille-P2265T and Marseille-P3890T showed that all digital DNA-DNA hybridization (dDDH), orthologous average nucleotide identity (OrthoANI) and average amino acid identity (AAI) values were lower than the published species thresholds (70% for dDDH, 95-96% for OrthoANI/AAI). Based on these results, it was concluded that strains Marseille-P2265T and Marseille-P3890T belong to two new genera in the family Oscillospiraceae. For these two genera, the names Neglectibacter gen. nov. and Scatolibacter gen. nov. were proposed, with strains Marseille-P2265T and Marseille-P3890T being the type strains of Neglectibacter timonensis gen. nov., sp. nov. and Scatolibacter rhodanostii gen. nov., sp. nov., respectively.

Vitreoscilla massiliensis sp. nov., Isolated From the Stool of an Amazonian Patient.

Strain SN6T is a non-motile and non-spore-forming gram-negative bacterium which was isolated from the stool sample of an Amazonian patient. The optimum growth was observed at 37 °C, pH 7, and 0-5 g/l of NaCl. Based on the 16S rRNA gene sequence similarity, the strain SN6T exhibited 97.5% identity with Vitreoscilla stercoraria strain ATCC_15218 (L06174), the phylogenetically closest species with standing in nomenclature. The predominant fatty acid was hexadecenoic acid (31%). The genomic DNA G + C content of the strain SN6T was 49.4 mol %. After analysis of taxonogenomic data, phenotypic and biochemical characteristics, we concluded that strain SN6T represents a new species of the genus Vitreoscilla for which the name Vitreoscilla massiliensis sp.nov is proposed. The type strain is SN6T (=CSUR P2036 = LN870312 = DSM 100958).

Gorillibacterium timonense sp. nov., isolated from an obese patient.

A Gram-negative and facultative anaerobic bacterium, designated strain SN4T, was isolated from the stool sample of an obese Amazonian patient. The new isolate was characterized by the taxonogenomics approach. The strain SN4T was beige-colored, circular and not haemolytic. Cells are rod shaped and motile with several flagella. Strain SN4T grows optimally at pH 7 and can survive in the presence of a saline concentration of up to 75 g/l NaCl. The 16S ribosomal RNA gene sequence analysis of the novel strain SN4T showed 95.28% similarity in nucleotide sequence with Gorillibacterium massiliense G5T, the phylogenetically closest neighbor and the type species of this genus. Anteiso-C15:0, iso-C15:0 and C16:0 were found as the major components in the cellular fatty acid analysis of this isolate. The genomic draft of strain SN4T is 5,263,742 bp long with 53.33% of G+C content. The differences in physiological, biochemical characteristics and phylogenetic and genomic data make it possible to clearly distinguish the strain SN4T from G. massiliense G5T. Based on the taxonogenomic description and the phenotypic and biochemical characteristics of this bacterium presented in this article, we propose the SN4T strain (= CSUR P2011 = DSM 100,698) as a new species, Gorillibacterium timonense sp. nov.

Draft Genome Sequence of Megamonas funiformis Strain Marseille-P3344, Isolated from a Human Fecal Microbiota.

In this article, we present the draft genome sequence of Megamonas funiformis strain Marseille-P3344, isolated from a human fecal sample. The genome described here is composed of 2,464,704 nucleotides, with 2,230 protein-coding genes and 76 RNA genes.

Blautia massiliensis sp. nov., isolated from a fresh human fecal sample and emended description of the genus Blautia.

The strain GD9T is the type strain of the newly proposed species Blautia massiliensis sp. nov., belonging to the family Lachnospiraceae. It was isolated from a fresh stool sample collected from a healthy human using the culturomics strategy. Cells are Gram-negative rods, oxygen intolerant, non-motile and non-spore forming. The 16S rRNA gene sequencing showed that strain GD9T was closely related to Blautia luti, with a 97.8% sequence similarity. Major fatty acids were C14:0 (19.8%) and C16:0 (53.2%). Strain GD9T exhibits a genome of 3,717,339 bp that contains 3,346 protein-coding genes and 81 RNAs genes including 63 tRNAs. The features of this organism are described here, with its complete genome sequence and annotation. Compared with other Blautia species which are Gram positive, the strain was Gram negative justifying an emended description of the genus Blautia.

Culture of previously uncultured members of the human gut microbiota by culturomics.

Metagenomics revolutionized the understanding of the relations among the human microbiome, health and diseases, but generated a countless number of sequences that have not been assigned to a known microorganism1. The pure culture of prokaryotes, neglected in recent decades, remains essential to elucidating the role of these organisms2. We recently introduced microbial culturomics, a culturing approach that uses multiple culture conditions and matrix-assisted laser desorption/ionization-time of flight and 16S rRNA for identification2. Here, we have selected the best culture conditions to increase the number of studied samples and have applied new protocols (fresh-sample inoculation; detection of microcolonies and specific cultures of Proteobacteria and microaerophilic and halophilic prokaryotes) to address the weaknesses of the previous studies3-5. We identified 1,057 prokaryotic species, thereby adding 531 species to the human gut repertoire: 146 bacteria known in humans but not in the gut, 187 bacteria and 1 archaea not previously isolated in humans, and 197 potentially new species. Genome sequencing was performed on the new species. By comparing the results of the metagenomic and culturomic analyses, we show that the use of culturomics allows the culture of organisms corresponding to sequences previously not assigned. Altogether, culturomics doubles the number of species isolated at least once from the human gut.