N. Labas

Faustoviruses: Comparative Genomics of New Megavirales Family Members

An emerging interest for the giant virus discovery process, genome sequencing and analysis has allowed an expansion of the number of known Megavirales members. Using the protist Vermamoeba sp. as cell support, a new giant virus named Faustovirus has been isolated. In this study, we describe the genome sequences of nine Faustoviruses and build a genomic comparison in order to have a comprehensive overview of genomic composition and diversity among this new virus family. The average sequence length of these viruses is 467,592.44 bp (ranging from 455,803 to 491,024 bp), making them the fourth largest Megavirales genome after Mimiviruses, Pandoraviruses, and Pithovirus sibericum. Faustovirus genomes displayed an average G+C content of 37.14 % (ranging from 36.22 to 39.59%) which is close to the G+C content range of the Asfarviridae genomes (38%). The proportion of best matches and the phylogenetic analysis suggest a shared origin with Asfarviridae without belonging to the same family. The core-gene-based phylogeny of Faustoviruses study has identified four lineages. These results were confirmed by the analysis of amino acids and COGs category distribution. The diversity of the gene composition of these lineages is mainly explained by gene deletion or acquisition and some exceptions for gene duplications. The high proportion of best matches from Bacteria and Phycodnaviridae on the pan-genome and unique genes may be explained by an interaction occurring after the separation of the lineages. The Faustovirus core-genome appears to consolidate the surrounding of 207 genes whereas the pan-genome is described as an open pan-genome, its enrichment via the discovery of new Faustoviruses is required to better seize all the genomic diversity of this family.

Loss of TSS1 in hypervirulent Coxiella burnetii 175, the causative agent of Q fever in French Guiana

In French Guiana, the unique Coxiella burnetii circulating genotype 17 causes 24% of community-acquired pneumonia, the highest prevalence ever described. To explain this unusual virulence, we performed a comparative genomic analysis of strain Cb175, which was isolated from a patient from French Guiana. Cb175 has a greater number of mutations in genes involved in metabolism compared with the Nine Mile I strain. We found a 6105bp fragment missing in Cb175, which corresponds to the Type 1 secretion systems (T1SS) hlyCABD operon region. This deletion was detected by a specific qPCR in the 8 other strains available from this territory an in none of 298C.burnetii strains from other areas and other genotypes (8/8 vs 0/298, Fishers exact test, p<0.0000001). Loss of genes implicated in secretion systems has been observed in other epidemic bacterial strains. Thus, the virulence of Cb175 may be linked to this genome reduction.

Characterization of Viral Communities of Biting Midges and Identification of Novel Thogotovirus Species and Rhabdovirus Genus

More than two thirds of emerging viruses are of zoonotic origin, and among them RNA viruses represent the majority. Ceratopogonidae (genus Culicoides) are well-known vectors of several viruses responsible for epizooties (bluetongue, epizootic haemorrhagic disease, etc.). They are also vectors of the only known virus infecting humans: the Oropouche virus. Female midges usually feed on a variety of hosts, leading to possible transmission of emerging viruses from animals to humans. In this context, we report here the analysis of RNA viral communities of Senegalese biting midges using next-generation sequencing techniques as a preliminary step toward the identification of potential viral biohazards. Sequencing of the RNA virome of three pools of Culicoides revealed the presence of a significant diversity of viruses infecting plants, insects and mammals. Several novel viruses were detected, including a novel Thogotovirus species, related but genetically distant from previously described tick-borne thogotoviruses. Novel rhabdoviruses were also detected, possibly constituting a novel Rhabdoviridae genus, and putatively restricted to insects. Sequences related to the major viruses transmitted by Culicoides, i.e., African horse sickness, bluetongue and epizootic haemorrhagic disease viruses were also detected. This study highlights the interest in monitoring the emergence and circulation of zoonoses and epizooties using their arthropod vectors.

Microbial culturomics unravels the halophilic microbiota repertoire of table salt: description of Gracilibacillus massiliensis sp. nov.

Background Microbial culturomics represents an ongoing revolution in the characterization of environmental and human microbiome. Methods By using three media containing high salt concentration (100, 150, and 200 g/L), the halophilic microbial culturome of a commercial table salt was determined. Results Eighteen species belonging to the Terrabacteria group were isolated including eight moderate halophilic and 10 halotolerant bacteria. Gracilibacillus massiliensis sp. nov., type strain Awa-1T (=CSUR P1441=DSM 29726), is a moderately halophilic gram-positive, non-spore-forming rod, and is motile by using a flagellum. Strain Awa-1T shows catalase activity but no oxidase activity. It is not only an aerobic bacterium but also able to grow in anaerobic and microaerophilic atmospheres. The draft genome of G. massiliensis is 4,207,226 bp long, composed of 13 scaffolds with 36.05% of G+C content. It contains 3,908 genes (3,839 protein-coding and 69 RNA genes). At least 1,983 (52%) orthologous proteins were not shared with the closest phylogenetic species. Hundred twenty-six genes (3.3%) were identified as ORFans. Conclusions Microbial culturomics can dramatically improve the characterization of the food and environmental microbiota repertoire, deciphering new bacterial species and new genes. Further studies will clarify the geographic specificity and the putative role of these new microbes and their related functional genetic content in environment, health, and disease.

Hugonella massiliensis gen. nov., sp. nov., genome sequence, and description of a new strictly anaerobic bacterium isolated from the human gut

The human gut is composed of a large diversity of microorganisms, which have been poorly described. Here, using culturomics, a new concept based on the variation in culture conditions and MALDI‐TOF MS identification, we proceed to explore the microbial diversity of the complex ecosystem of the human gut. Using this approach, we isolated strain AT8T (=CSUR P2118 = DSM 101782) from stool specimens collected from a 51‐year‐old obese French woman. Strain AT8T is a strictly anaerobic, nonmotile, nonspore‐forming gram‐positive coccus that do not exhibit catalase and oxidase activities. 16S rDNA‐based identification of strain AT8T demonstrated 92% gene sequence similarity with Eggerthella lenta DSM 2243, the phylogenetically closed validly named type species. Here, we present a set of features for the strain AT8T and the description of its complete genome sequence and annotation. The 2,091,845 bp long genome has a G+C content of 63.46% and encodes1,849 predicted genes; 1,781 were protein‐coding genes, and 68 were RNAs. On the basis of the characteristics reported here, we propose the creation of a new bacterial genus Hugonella gen. nov., belonging to the Eggerthellaceae family and including Hugonella massiliensis gen. nov., sp. nov., strain AT8T as the type strain.

High-quality genome sequencing and description of Dermabacter indicis sp. nov.

Strain FF11T was isolated from the wound on a researchers finger who had been bitten by a fish (Protopterus annectens) in Senegal. Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry did not provide any identification, but the 16S rRNA sequence exhibited 97.9% identity with Dermabacter hominis. Phenotypic and genomic analyses demonstrated that strain FF11T is Gram-positive, facultatively anaerobic, nonmotile and non–spore forming; it exhibited a genome of 2 222 902 bp encoding 2074 protein-coding and 50 RNA genes, with a 63.2% G+C content. We consequently proposed the creation of Dermabacter indicis strain FF11T.

Noncontiguous finished genome sequence and description of Murdochiella massiliensis strain SIT12 sp. nov.

Murdochiella massiliensis strain SIT12 (= CSUR P1987 = DSM 29078) is the type strain of M. massiliensis sp. nov. This bacterium was isolated from the stool of a healthy 2-year-old Senegalese boy. M. massiliensis is an anaerobic, Gram-positive coccus. The genome size of M. massiliensis strain SIT12 is 1 642 295 bp with 48.9% G+C content and assembled into two scaffolds.

Noncontiguous finished genome sequence and description of Weeksella massiliensis sp. nov.

Strain FF8T (= CSUR P860 = DSM 28259) was isolated in Dakar, Senegal, from the urine of a 65-year-old man with acute cystitis. This strain shows a similarity of sequence of 16S rRNA of 98.38% with Weeksella virosa, and its GenBank accession numbers are HG931340 and CCMH00000000. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis had a poor score, ranging from 1.32 to 1.56, that did not allow identification of the bacterium. Using a polyphasic study made of phenotypic and genomic analyses, strain FF8T was a Gram-negative, aerobic rod and a member of the family Flavobacteriaceae. The sequenced genome is 2 562 781 bp with one chromosome but no plasmid. It exhibits a G + C content of 35.9% and contains 2390 protein-coding and 56 RNA genes, including a complete rRNA operon. On the basis of these data, we propose the creation of Weeksella massiliensis sp. nov.

Massilibacterium senegalense gen. nov., sp. nov., a new bacterial genus isolated from the human gut

Massilibacterium senegalense gen. nov., sp. nov., strain mt8T, is the type strain of Massilibacterium gen. nov., a new genus within the Bacillaceae family. This Gram-negative facultative anaerobic rod was isolated from the gut microbiota of a severely malnourished boy. Its phenotypic description is hereby presented with a complete annotation of its genome sequence. This genome is 5 697 950 bp long and contains 5615 protein-coding genes and 178 RNA genes, among which are 40 rRNA genes.

Clostridium polynesiense sp. nov., a new member of the human gut microbiota in French Polynesia

Strain MS1, a Gram-positive, obligately anaerobic, motile and spore-forming rod belonging to the Clostridium genus, was isolated from the feces of a healthy Polynesian male living in French Polynesia. The temperature range for growth was 30-45 °C. We sequenced its complete genome and studied its phenotypic characteristics. The 3,560,738-bp long genome (one chromosome, no plasmid, G + C content 34%) contained 3535 protein-coding and 70 RNA genes. Strain MS1 exhibited a 98.24% 16S rRNA similarity with Clostridium amylolyticum, the phylogenetically closest species. When compared with other Clostridium species with standing in nomenclature, it had an average genomic similarity of 68.8-70%, a unique MALDI-TOF spectrum, and differed in nitrate reduction, motility and L-arabinose and D-lactose metabolism with most of the closest species. Therefore, strain MS1 is sufficiently distinct from type strains of the genus Clostridium to represent a novel species within this genus, for which the name Clostridium polynesiense sp. nov. is proposed. The type strain of C. polynesiense is MS1(T) (= CSUR P630 = DSM 27072).