Saccamoeba lacustris, sp. nov. (Amoebozoa: Lobosea: Hartmannellidae), a new lobose amoeba, parasitized by the novel chlamydia 'Candidatus Metachlamydia lacustris' (Chlamydiae: Parachlamydiaceae)

Eur J Protistol. 2010 May;46(2):86-95. doi: 10.1016/j.ejop.2009.11.002. Epub 2010 Mar 27.


An amoeba isolated from an aquatic biotope, identified morphologically as Saccamoeba limax, was found harbouring mutualistic rod-shaped gram-negative bacteria. During their cultivation on agar plates, a coinfection also by lysis-inducing chlamydia-like organisms was found in some subpopulations of that amoeba. .Here we provide a molecular-based identification of both the amoeba host and the two bacterial endosymbionts. Analysis of the 18S rRNA gene revealed that this strain is the sister-group to Glaeseria, for which we proposed the name Saccamoeba lacustris. The rod-shaped endosymbiont was identified as a member of Variovorax paradoxus group (Comamonadaceae, Beta-Proteobacteria). No growth on bacteriological agars was recorded, hence this symbiont might be strictly intracellular. The chlamydia-like parasite was unable to infect Acanthamoeba and other amoebae in coculture, showing high host specificity. Phylogenetic analysis based on the 16S rDNA indicated that it is a new member of the family Parachlamydiaceae (order Chlamydiales), for which we proposed the name 'Candidatus Metachlamydia lacustris'.

MeSH terms

  • Acanthamoeba / classification*
  • Acanthamoeba / isolation & purification*
  • Acanthamoeba / ultrastructure
  • Cluster Analysis
  • Comamonadaceae / classification*
  • Comamonadaceae / isolation & purification*
  • Comamonadaceae / ultrastructure
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • DNA, Protozoan / chemistry
  • DNA, Protozoan / genetics
  • Lobosea / classification*
  • Lobosea / microbiology*
  • Lobosea / ultrastructure
  • Microscopy
  • Microscopy, Electron, Transmission
  • Molecular Sequence Data
  • Phylogeny
  • RNA, Bacterial / genetics
  • RNA, Ribosomal, 16S / genetics
  • RNA, Ribosomal, 18S / genetics
  • Sequence Analysis, DNA


  • DNA, Bacterial
  • DNA, Protozoan
  • RNA, Bacterial
  • RNA, Ribosomal, 16S
  • RNA, Ribosomal, 18S

Associated data

  • GENBANK/GQ221845
  • GENBANK/GQ221846
  • GENBANK/GQ221847