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Shedding light on microbial dark matter: a TM 6 bacterium as natural endosymbiont of a free‐living amoeba
Author(s) -
Delafont Vincent,
SambaLouaka Ascel,
Bouchon Didier,
Moulin Laurent,
Héchard Yann
Publication year - 2015
Publication title -
environmental microbiology reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.229
H-Index - 69
ISSN - 1758-2229
DOI - 10.1111/1758-2229.12343
Subject(s) - biology , bacteria , microbiology and biotechnology , amoeba (genus) , strain (injury) , 16s ribosomal rna , protozoa , gene , genetics , anatomy
Summary The TM 6 phylum belongs to the so‐called microbial dark matter that gathers uncultivated bacteria detected only via DNA sequencing. Recently, the genome sequence of a TM 6 bacterium ( TM 6 SC 1) has led to suggest that this bacterium would adopt an endosymbiotic life. In the present paper, free‐living amoebae bearing a TM 6 strain were isolated from a water network. The amoebae were identified as V ermamoeba vermiformis and the presence of a TM 6 strain was detected by polymerase chain reaction and microscopy. The partial sequence of its 16S rRNA gene showed this strain to be closely related to the sequenced TM 6 SC 1 strain. These bacteria displayed a pyriform shape and were found within V . vermiformis . Therefore, these bacteria were named V ermiphilus pyriformis . Interactions studies showed that V . pyriformis was highly infectious and that its relation with V . vermiformis was specific and highly stable. Finally, it was found that V . pyriformis inhibited the encystment of V . vermiformis . Overall, this study describes for the first time an endosymbiotic relationship between a TM 6 bacterium and a free‐living amoeba in the environment. It suggests that other bacteria of the TM 6 phylum might also be endosymbiotic bacteria and may be found in other free‐living amoebae or other organisms.