Shaping the tripartite symbiosis: are termite microbiome functions directed by the environmentally acquired fungal cultivar?

Microbiome assembly critically impacts the ability of hosts to access beneficial symbiont functions. Fungus-farming termites have co-evolved with a fungal cultivar as a primary food source and complex gut microbiomes, which collectively perform complementary degradation of plant biomass. A large subset of the bacterial community residing within termite guts are inherited (vertically transmitted) from parental colonies, while the fungal symbiont is, in most termite species, acquired from the environment (horizontally transmitted).