ABSTRACT
Fluorescent in situ hybridization with a 16S rRNA probe specific for
Verrucomicrobia
was used to (i) confirm the division-level identity of and (ii) study the behavior of the obligate intracellular verrucomicrobium “
Candidatus
Xiphinematobacter” in its nematode hosts. Endosymbionts in the egg move to the pole where the gut primordium arises; hence, they populate the intestinal epithelia of juvenile worms. During the host's molt to adult female, the endosymbionts concentrate around the developing ovaries to occupy the ovarian wall. Some bacteria are enclosed in the ripening oocytes for vertical transmission.
Verrucomicrobia
in males stay outside the testes because the tiny spermatozoids are not suitable for transmission of cytoplasmic bacteria.