Host-Symbiont Cospeciation of Termite-Gut Cellulolytic Protists of the Genera <i>Teranympha</i> and <i>Eucomonympha</i> and their <i>Treponema</i> Endosymbionts

Abstract

Cellulolytic flagellated protists inhabit the hindgut of termites. They are unique and essential to termites and related wood-feeding cockroaches, enabling host feeding on cellulosic matter. Protists of two genera in the family Teranymphidae (phylum Parabasalia), Eucomonympha and Teranympha, are phylogenetically closely related and harbor intracellular endosymbiotic bacteria from the genus Treponema. In order to obtain a clearer understanding of the evolutionary history of this triplex symbiotic relationship, the molecular phylogenies of the three symbiotic partners, the Teranymphidae protists, their Treponema endosymbionts, and their host termites, were inferred and compared. Strong congruence was observed in the tree topologies of all interacting partners, implying their cospeciating relationships. In contrast, the coevolutionary relationship between the Eucomonympha protists and their endosymbionts was more complex, and evidence of incongruence against cospeciating relationships suggested frequent host switches of the endosymbionts, possibly because multiple Eucomonympha species are present in the same gut community. Similarities in the 16S rRNA and gyrB gene sequences of the endosymbionts were higher among Teranympha spp. (>99.25% and >97.2%, respectively), whereas those between Teranympha and Eucomonympha were lower (<97.1% and <91.9%, respectively). In addition, the endosymbionts of Teranympha spp. formed a phylogenetic clade distinct from those of Eucomonympha spp. Therefore, the endosymbiont species of Teranympha spp., designated here as “Candidatus Treponema teratonymphae”, needs to be classified as a species distinct from the endosymbiont species of Eucomonympha spp.

Novel features of centriole polarity and cartwheel stacking revealed by cryo-tomography

“…The gut of R. speratus termites contains another symbiotic flagellate, namely Teranympha mirabilis (Koidzumi, 1921;Noda et al, 2018), which we found also to harbor numerous centrioles and associated flagella ( Fig. S8A).…”

Composition and Function of Chicken Gut Microbiota

“…Common but numerically poorly represented microbiota members belong to genera Treponema, Fusobacterium, Akkermansia, Mucispirillum, Elusimicrobium or Cloacibacillus, each of them belonging to a different phylum such as Spirochaetes, Fusobacteria, Verrucomicrobia, Defferibacteres, Elusimicrobia and Synergistetes, respectively. Treponema species are likely involved in fibre digestion as this is their function in termite microbiota [47] and enrichment for Treponema has been described also in humans from rural areas [48,49]. Treponema species are also more common in pigs [50,51], whose feed formula is rich in plant fibre.…”

Genome analyses of uncultured TG2/ZB3 bacteria in ‘Margulisbacteria’ specifically attached to ectosymbiotic spirochetes of protists in the termite gut

“…In co-cultures of T. primitia and H 2 -producing Treponema azotonutricium, interspecies transfer of H 2 was demonstrated [80]. In 'Candidatus Treponema intracellularis' and 'Candidatus Treponema teratonymphae', which are intracellular symbionts of parabasalid protists, it has been hypothesised that these endosymbiotic H 2 /CO 2 -homoacetogens decrease the high H 2 partial pressure inside their protist hosts, thereby promoting the fermentation process of host cells [65,81]. However, to the best of our knowledge, the attachment of an H 2 -producing bacterium to an H 2 /CO 2 -homoacetogenic spirochete has hitherto never been reported.…”