Non-Ribosomal Peptide Synthase Profiles remain structurally similar despite minimally shared features across fungus-farming termite microbiomes

Abstract

Fungus-farming termites (Macrotermitinae) engage in an obligate mutualism with members of the fungal genus Termitomyces, which they maintain as a monoculture on specialised comb structures. Both these comb structures and the guts of the termites host diverse bacterial communities that are believed to assist in sustaining monoculture farming through antagonist suppression. Candidate bacteria-derived compounds serving this function are non-ribosomal peptides (NRPs), which are a highly bioactive class of specialised metabolites, frequently produced by symbionts within eukaryotic hosts. However, our understanding of specialised metabolites in the termite-associated microbiomes is limited. Here we use amplicon sequencing to characterise both bacterial composition and NRP potential. We show that bacterial and NRP diversity are correlated and that the former varies more than the latter across termite host and gut and comb samples. Compositions of the two were governed by host species and sample type, with topological similarity indicating a diverse set of biosynthetic potential that is consistent with the long evolutionary history of the Macrotermitinae. The structure of both bacterial and NRP compositional networks varied similarly between guts and combs across the Macrotermitinae with auxiliary termite genus-specific patterns. We observed minimal termite species-specific cores, with essentially no Macrotermitinae-wide core and an abundance of putatively novel BGCs, suggesting that there is likely no single solution to antagonist suppression via specialised metabolites. Our findings contribute to an improved understanding of the identities and distribution of NRP potential in the farming termite symbiosis and will help guide targeted exploration of specialised metabolite production.