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Phylogenetic characterization of Legionella ‐like endosymbiotic X‐bacteria in Amoeba proteus : a proposal for ‘ Candidatus Legionella jeonii’ sp. nov
Author(s) -
Park Miey,
Yun Seong Tae,
Kim Mu Soo,
Chun Jongsik,
Ahn Tae In
Publication year - 2004
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2004.00659.x
Subject(s) - biology , legionella , microbiology and biotechnology , rpob , 16s ribosomal rna , bacteria , amoeba proteus , phylogenetics , candidatus , phylogenetic tree , ribosomal rna , gene , genetics , amoeba (genus)
Summary The X‐bacteria which initiated organismic association with the D strain of Amoeba proteus in 1966 as parasites have changed to obligate endosymbionts on which the host depends for survival. Owing to the difficulty in cultivating the bacteria in vitro , the identity of X‐bacteria has not been determined. As the life cycle of X‐bacteria is similar to that of Legionella spp. in soil amoebae, we applied the polymerase chain reaction method with specific primers aimed at Legionella spp. for the detection and cloning of 16S rRNA gene. The identity and intracellular localization of the endosymbiont were confirmed by the application of a specific fluorescently labelled 16S rRNA‐targeted probe. In addition we cloned RNA polymerase β‐subunit gene ( rpoB ) of X‐bacteria by genomic library tagging. A phylogenetic analysis of the 16S rRNA gene placed the bacterium within a unique monophyletic group containing all other members of the genus Legionella . Phylogeny from rpoB and mip genes further confirmed the taxonomic context of X‐bacteria to be a Legionella sp. In all three phylogenic analyses, X‐bacterium was placed apart from Legionella ‐like amoebal pathogens present in soil amoebae. Thus, we propose the name ‘ Candidatus Legionella jeonii’ sp. nov. for the endosymbiotic X‐bacteria in Amoeba proteus .