Bacterial Culture‐Based Analysis of the Tuatara Gut Reveals Functional Roles of the Core Genus <i>Chryseobacterium</i>

The microorganisms living in a host's gut are important for digestion and immune response and are an important facet to understanding host ecology. For tuatara, the gut microbiome presents an opportunity to examine bacteria associated with a long‐lived and evolutionarily distinct reptile and to understand how tuatara ecology is mediated or supported by gut microbes. Here, we used culturing from tuatara cloacal swabs to isolate bacterial symbionts in pure culture. We identified these using 16S rRNA gene sequencing and then employed whole‐genome sequencing of a subset of isolates to examine their functional potential. We identified 43 morphologically distinct isolates from 13 genera, encompassing the four main phyla commonly identified in previous tuatara studies. Seven isolates were from genus Chryseobacterium , for which we identified a likely role in degrading complex plant polysaccharides and insect chitin, potentially filling a functional niche in tuatara left vacant by the relatively low abundance of bacteria commonly found in other reptiles. This study leverages obtaining core members (present in ≥80% of individuals) of the tuatara microbiome in pure culture to elucidate the functional role that these bacteria likely play for their host and provides a better understanding of how bacteria mediate the relationship between tuatara and their ecology.