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16S rRNA RefSeq: V15.22    Genomic RefSeq: V9.15
Genus: Actinomyces
Lineage: Bacteria;Actinobacteria;Actinomycetia;Actinomycetales;Actinomycetaceae;Actinomyces
Overview: Bacteria of the genus Actinomyces are abundant in the healthy oral microbiome, making up 5-10% of the cells in dental plaque. In 2018 some species formerly considered to be Actinomyces were reclassified into genus Schaalia, including several species abundant on the tongue (Nouioui et al. 2018). Twelve oral species remain in the genus Actinomyces include A. naeslundii, A. oris, and A. graevenitzii.

Ecological role/importance in health and disease: A. naeslundii and its relatives are early colonizers in the dental plaque biofilm (Diaz et al. 2006, Dige et al. 2009). A. graevenitzii is abundant in the biofilm on the tongue. Some species, particularly A. israelii and A. gerencseriae, are in lower abundance in the healthy microbiome but can cause opportunistic infections known as actinomycosis.

Actinomyces Image
Actinomyces (yellow) intermingled with Corynebacterium (magenta) in human dental plaque. From Mark Welch et al. 2016
eHOMD Taxonomy
LifeCellular Organisms
 DomainBacteria (788) Abundance
  PhylumActinobacteria (119) Abundance
   ClassActinomycetia (104) Abundance
    OrderActinomycetales (34) Abundance
     FamilyActinomycetaceae (34) Abundance
      GenusActinomyces (21) Abundance
       Species       Actinomyces dentalis (HMT-888) Abundance
       Actinomyces gerencseriae (HMT-618) Abundance
       Actinomyces graevenitzii (HMT-866) Abundance
       Actinomyces israelii (HMT-645) Abundance
       Actinomyces johnsonii (HMT-849) Abundance
       Actinomyces massiliensis (HMT-852) Abundance
       Actinomyces naeslundii (HMT-176) Abundance
       Actinomyces oricola (HMT-708) Abundance
       Actinomyces oris (HMT-893) Abundance
       Actinomyces radicidentis (HMT-746) Abundance
       Actinomyces sp._HMT_169 (HMT-169) Abundance
       Actinomyces sp._HMT_170 (HMT-170) Abundance
       Actinomyces sp._HMT_171 (HMT-171) Abundance
       Actinomyces sp._HMT_175 (HMT-175) Abundance
       Actinomyces sp._HMT_414 (HMT-414) Abundance
       Actinomyces sp._HMT_448 (HMT-448) Abundance
       Actinomyces sp._HMT_525 (HMT-525) Abundance
       Actinomyces sp._HMT_896 (HMT-896) Abundance
       Actinomyces sp._HMT_897 (HMT-897) Abundance
       Actinomyces timonensis (HMT-179) Abundance
       Actinomyces viscosus (HMT-688) Abundance