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By diversifying culture conditions, in a strategy named culturomics, we were able in a short time to grow 124 new bacterial species from human stools, including 39 strict anaerobes. To describe these microorganisms, we use genome sequencing and MALDI-TOF mass spectrometry. Both tools have been major breakthroughs in clinical microbiology over the past decade, have previously been used for taxonomic purposes, and have the advantage over chemotaxonomic methods and DNA-DNA hybridization, to exhibit an excellent intra- and inter-laboratory reproducibility. We developed a polyphasic taxonomic strategy including MALDI-TOF MS and genomic analyses to describe new bacterial species associated with human beings. This strategy, that we have named taxono-genomics, was used to propose the description of 48 new species, the names of 13 of which have officially been validated. In this manuscript, we briefly reviewed the pros and cons of the currently validated taxonomic tools and propose that genomic sequencing and MALDI-TOF mass spectrometry may be incorporated in the taxonomic classification of prokaryotes., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Bacterial culture was the first method used to describe the human microbiota, but this method is considered outdated by many researchers. Metagenomics studies have since been applied to clinical microbiology; however, a "dark matter" of prokaryotes, which corresponds to a hole in our knowledge and includes minority bacterial populations, is not elucidated by these studies. By replicating the natural environment, environmental microbiologists were the first to reduce the "great plate count anomaly," which corresponds to the difference between microscopic and culture counts. The revolution in bacterial identification also allowed rapid progress. 16S rRNA bacterial identification allowed the accurate identification of new species. Mass spectrometry allowed the high-throughput identification of rare species and the detection of new species. By using these methods and by increasing the number of culture conditions, culturomics allowed the extension of the known human gut repertoire to levels equivalent to those of pyrosequencing. Finally, taxonogenomics strategies became an emerging method for describing new species, associating the genome sequence of the bacteria systematically. We provide a comprehensive review on these topics, demonstrating that both empirical and hypothesis-driven approaches will enable a rapid increase in the identification of the human prokaryote repertoire., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Multilocus sequence typing gives us unparalleled insights into the population biology of bacterial species, including those that cause healthcare-associated and/or community-acquired infections. For many of these species, we now recognize the existence of internationally prevalent clones, which are often resistant to multiple antibiotics.

Infections caused by foodborne bacterial pathogens continue to be a major public health issue around the world. During the past decade, pulsed-field gel electrophoresis (PFGE) has become the gold standard for molecular subtyping and source tracking of most foodborne bacteria. Owing to problems inherent in PFGE technology, new methods have been developed focusing on DNA sequence-based subtyping. This review discusses the feasibility of using multilocus sequence typing, multiple-locus variable-number tandem repeat analysis, single nucleotide polymorphisms, microarrays, whole genome sequencing and mass spectrometry for subtyping foodborne bacterial pathogens.

Background: Polymorphic tandem repeat typing is a new generic technology which has been proved to be very efficient for bacterial pathogens such as B. anthracis, M. tuberculosis, P. aeruginosa, L. pneumophila, Y. pestis. The previously developed tandem repeats database takes advantage of the release of genome sequence data for a growing number of bacteria to facilitate the identification of tandem repeats. The development of an assay then requires the evaluation of tandem repeat polymorphism on well-selected sets of isolates. In the case of major human pathogens, such as S. aureus, more than one strain is being sequenced, so that tandem repeats most likely to be polymorphic can now be selected in silico based on genome sequence comparison., Results: In addition to the previously described general Tandem Repeats Database, we have developed a tool to automatically identify tandem repeats of a different length in the genome sequence of two (or more) closely related bacterial strains. Genome comparisons are pre-computed. The results of the comparisons are parsed in a database, which can be conveniently queried over the internet according to criteria of practical value, including repeat unit length, predicted size difference, etc. Comparisons are available for 16 bacterial species, and the orthopox viruses, including the variola virus and three of its close neighbors., Conclusions: We are presenting an internet-based resource to help develop and perform tandem repeats based bacterial strain typing. The tools accessible at http://minisatellites.u-psud.fr now comprise four parts. The Tandem Repeats Database enables the identification of tandem repeats across entire genomes. The Strain Comparison Page identifies tandem repeats differing between different genome sequences from the same species. The "Blast in the Tandem Repeats Database" facilitates the search for a known tandem repeat and the prediction of amplification product sizes. The "Bacterial Genotyping Page" is a service for strain identification at the subspecies level.

Microbiology has entered the postgenomic era and it is clear that bacterial typing should aim to be based on analysis of complete genomes. Although complete genome sequencing for epidemiological typing remains unrealistic for the present, microarrays that provide information on gene content are now becoming available. Microarrays comprised of several thousand probes on glass slides can now be manufactured in the laboratory using robotic arrayers. The gene probes are either PCR products or synthetic oligonucleotides that can be irreversibly attached to a reactive glass surface. The target nucleic acids to be hybridized to the probe array are tagged with fluorescent dyes. Relative probe hybridization signals can be measured when two or more different preparations are labeled with distinguishable fluorophores. Microarrays that include probes for every gene within a genome provide excellent comparative data, although a focus on variable genes may be more useful for typing purposes. Composite arrays of variable genes are under development.