title: Classifying the uncultivated microbial majority: A place for metagenomic data in the Candidatus proposal.
abstract: Microbial taxonomists have generally been reluctant to accept the valid publication of names of uncultured taxa given that only pure cultures allow for a thorough description of the genealogy, genetics and phenotype of the putative taxa to be classified. The classification of conspicuous uncultured organisms has been considered into the Candidatus provisional status, but this is only possible with organisms for which it is possible to retrieve basic data on phylogeny, morphology, ecology and some metabolic traits that unequivocally identify them. The current developments on modern sequencing techniques, and especially metagenomics, allow the recognition of discrete populations of DNA sequences in environmental samples, which can be considered to belong to individual closely related populations that may be identified as members of yet-to-be described species. The recognition of such populations of (meta)genomes allow the retrieval of valuable taxonomic information, i.e. genealogy, genome, phenotypic coherence with other populations, and ecological relevant traits. Such traits may be included in the Candidatus proposals of environmentally occurring, yet uncultured species not exhibiting exceptional morphologies, phenotypes or ecological relevancies.
authors: School of Civil and Environmental Engineering, Georgia Institute of Technology, 311 Ferst Dr. NW, Atlanta, GA 30332, USA; School of Biology, Georgia Institute of Technology, 311 Ferst Dr. NW, Atlanta, GA 30332, USA. Electronic address: kostas@ce.gatech.edu.
authors: Konstantinos T
authors: KT
authors: Konstantinidis
authors: Marine Microbiology Group, Institut Mediterrani d'Estudis Avançats (IMEDEA; CSIC-UIB), E-07190 Esporles, Spain. Electronic address: rossello-mora@uib.es.
authors: Ramon
authors: R
authors: Rosselló-Móra
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics; D001431:Bacteriological Techniques; D019295:Computational Biology; D056186:Metagenomics; D059010:Single-Cell Analysis
keywords: 16 rRNA gene; Candidatus; Metagenomics; Species concept; Taxonomy; Uncultivated diversity