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Actinomyces naeslundii is an important early colonizer in the oral biofilm and consists of three genospecies (1, 2 and WVA 963) which cannot be readily differentiated using conventional phenotypic testing or on the basis of 16S rRNA gene sequencing. We have investigated a representative collection of type and reference strains and clinical and oral isolates (n=115) and determined the partial gene sequences of six housekeeping genes (atpA, rpoB, pgi, metG, gltA and gyrA). These sequences identified the three genospecies and differentiated them from Actinomyces viscosus isolated from rodents. The partial sequences of atpA and metG gave best separation of the three genospecies. A. naeslundii genospecies 1 and 2 formed two distinct clusters, well separated from both genospecies WVA 963 and A. viscosus. Analysis of the same genes in other oral Actinomyces species (Actinomyces gerencseriae, A. israelii, A. meyeri, A. odontolyticus and A. georgiae) indicated that, when sequence data were obtained, these species each exhibited <90 % similarity with the A. naeslundii genospecies. Based on these data, we propose the name Actinomyces oris sp. nov. (type strain ATCC 27044T =CCUG 34288T) for A. naeslundii genospecies 2 and Actinomyces johnsonii sp. nov. (type strain ATCC 49338T =CCUG 34287T) for A. naeslundii genospecies WVA 963. A. naeslundii genospecies 1 should remain as A. naeslundii sensu stricto, with the type strain ATCC 12104T =NCTC 10301T =CCUG 2238T.
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International Journal of Systematic and Evolutionary Microbiology vol. 59 , part 3, pp. 509 - 516
Supplementary Table S1. 16S rRNA gene sequence similarity between groups
Supplementary Table S2. Strains used and accession numbers for partial 16S rRNA gene sequences
Supplementary Table S3. Details of oral and non-oral isolates and reference and type strains used in this study and GenBank accession numbers of partial sequences
Supplementary Fig. S1. Phylogenetic relationships between A. naeslundii genospecies 1 ( A. naeslundii sensu stricto ), genospecies 2 ( A. oris sp. nov.) and serotype WVA 963 ( A. johnsonii sp. nov.), generated by neighbour-joining analysis of partial gene sequences of rpoB , gyrA , pgi and gltA
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