Thursday, August 2, 2007 - 9:00 AM
S168
Nomenclature rules, changes, accepted names and competing taxonomies
Paul De Vos, Laboratory for Microbiology, department WE10, Ghent University, K.L. Ledeganckstraat 35, Ghent, Belgium
Bacterial taxonomy concerns: (i) ordening of organisms in taxonomic groups = Classification; (ii) naming the groups of (i) = Nomenclature; (III) determining whether an organism belongs to a group, defined in (i) and named in (II) = Identifiction.
The taxonomic groups are delineated according to the generally accepted phylogeny i.e. comparative analysis of 16S rDNA sequence. A hierarchical system from ‘Domain’ to ‘Species’ covers the various taxonomic levels. Bacterial species may contain large numbers of strains and the bacterial species concept in use, is a phylogenetically supported concept. Below 97% (there is a debate going on the exact cut-off level) 16S rDNA sequence similarity discriminates bacterial species. Above 97% similarity, overall DNA-DNA hybridisations are needed to allocate a strain to a species. 70% DNA relatedness cuts off at the species level (including a DTm(e) of = or < than 5°C). Other methodologies are currently in development and validation to replace the laborious DNA-DNA methodology. Rules for naming bacterial taxa (nomenclature) are strict and compiled in the “International Code of Nomenclature of bacteria” (www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=icnb). Description of taxa/species are linked to biological reference material that must be available to the public. All bacterial taxonomic proposals and the reference biological material, linked to them are published in one taxonomic journal i.e. The International Journal of Systematic and Evolutionary Microbiology. Bacterial diversity is aimed at being only fragmentarily known whether the present taxonomic system will be able to cope with long term explorations of this diversity is unclear.
The taxonomic groups are delineated according to the generally accepted phylogeny i.e. comparative analysis of 16S rDNA sequence. A hierarchical system from ‘Domain’ to ‘Species’ covers the various taxonomic levels. Bacterial species may contain large numbers of strains and the bacterial species concept in use, is a phylogenetically supported concept. Below 97% (there is a debate going on the exact cut-off level) 16S rDNA sequence similarity discriminates bacterial species. Above 97% similarity, overall DNA-DNA hybridisations are needed to allocate a strain to a species. 70% DNA relatedness cuts off at the species level (including a DTm(e) of = or < than 5°C). Other methodologies are currently in development and validation to replace the laborious DNA-DNA methodology. Rules for naming bacterial taxa (nomenclature) are strict and compiled in the “International Code of Nomenclature of bacteria” (www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=icnb). Description of taxa/species are linked to biological reference material that must be available to the public. All bacterial taxonomic proposals and the reference biological material, linked to them are published in one taxonomic journal i.e. The International Journal of Systematic and Evolutionary Microbiology. Bacterial diversity is aimed at being only fragmentarily known whether the present taxonomic system will be able to cope with long term explorations of this diversity is unclear.
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See more of The Annual Meeting and Exhibition 2007 (July 29 - August 2, 2007)