Two possibly novel Alistipes species isolated from clinical specimens of human origin

Abstract number: 1134_01_329

Finegold S., Song Y., Liu C., Bolanos M., McTeague M.


In this study, two groups of unusual bacteria, which phenotypically resemble members of Alistipes, but phylogenetically display >= 3% 16S rRNA sequence divergence with their mostly closely related species, Alistipes finegoldii were fully characterized.


The 7 isolates (4 for group I and 3 for group II) were biochemically characterized by using a combination of conventional tests as described in the Wadsworth and VPI anaerobic manuals plus the API ZYM, rapid ID 32, and Rapid ANA II systems. The 16S rRNA genes of the isolates were sequenced by an automatic 373A DNA sequencer. Sequence data was analysed by using the programmes FASTA and DNATools.


Phylogenetically and phenotypically, the unidentified bacteria displayed a relatively close association with each other. However, a 16S rRNA gene sequence divergence of approximately 4% between the two unknown bacteria, as well as distinguishable biochemical characteristics such as different activities of b-glucosidase, a-arabinosidase and p-nitrophenylphosphatase, demonstrate that these organisms are genotypically and phenotypically distinct and each group represents a previously unknown sub-line within the Alistipes phylogenetic cluster. The closest described species to both of them is A. finegoldii (approximate 97% similarity), but group I can be differentiated from A. finegoldii by positive b-glucosidase reaction, and group II can be distinguished from A. finegoldii by being a-arabinosidase positive.


Additional studies are in progress, but based on the phenotypic and phylogenetic findings to date, it appears that these two groups may represent two novel species in the genus Alistipes.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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