Abstracts (first author)
Culture-independent characterisation of the core gut microbiome of fungus-growing termites
Fungus-growing termites (subfamily Macrotermitinae, family Termitidae) live in an obligate mutualistic symbiosis with the fungus Termitomyces. All other termites rely on gut microbes for the breakdown of plant material and other forage, and it has been generally assumed that the association with Termitomyces has reduced the need for fermentative gut microbes after the Macrotermitinae became fungus-farmers. Only few studies have explored this in any detail and the identities, levels of interaction-specificity with the termite host, and consistency in bacterial communities between host species have remained largely unknown. Here, we employ bacterial 16S rRNA 454 high-throughput pyrosequencing to identify a potential core microbiome in the fungus-growing termites - i.e., a distinct set of bacteria present across lineages in the termite phylogeny. Comparative analysis of 9 fungus-growing termite species from 5 genera suggests that a core gut microbiome indeed exists, as all bacterial taxa of high abundance were present in all termite species examined. However, quantitative differences in microbiome composition between termite species and genera were also noticed, possibly associated with differences in substrate use and Termitomyces lineage reared. Our results are consistent with major changes in gut microbiomes having occurred when fungus farming evolved 30 MYA, followed by relatively modest elaborations in response to ecological conditions. This might help explain why neither the termites nor Termitomyces ever abandoned the symbiosis or teamed-up with another termite of fungal partner lineage.