Bacterial community profiling highlights complex diversity and novel organisms in wildlife ticks

Ticks (Acari: Ixodida) transmit a greater variety of pathogens than any other blood-feeding arthropod. While numerous microbes have been identified inhabiting Australian Ixodidae, some of which are related to globally important tick-borne pathogens, little is known about the bacterial communities within ticks collected from Australian wildlife. In this study, 1,019 ticks were identified on 221 hosts spanning 27 wildlife species. Next-generation sequencing was used to amplify the V1-2 hypervariable region of the bacterial 16S rRNA gene from 238 ticks; Amblyomma triguttatum (n=6), Bothriocroton auruginans (n=11), Bothriocroton concolor (n=20), Haemaphysalis bancrofti (n=10), Haemaphysalis bremneri (n=4), Haemaphysalis humerosa (n=13), Haemaphysalis longicornis (n=4), Ixodes antechini (n=29), Ixodes australiensis (n=26), Ixodes fecialis (n=13), Ixodes holocyclus (n=37), Ixodes myrmecobii (n=1), Ixodes ornithorhynchi (n=10), Ixodes tasmani (n=51) and Ixodes trichosuri (n=3). After bioinformatic analyses, over 14 million assigned bacterial sequences revealed the presence of newly described bacteria 9Ca. Borrelia tachyglossi9, 9Ca. Neoehrlichia australis9, 9Ca. Neoehrlichia arcana9 and 9Ca. Ehrlichia ornithorhynchi9. Furthermore, three novel Anaplasmataceae species were identified including; a Neoehrlichia sp. in I. australiensis and I. fecialis ex quenda (Isoodon fusciventer) (Western Australia), an Anaplasma sp. from one B. concolor ex echidna (Tachyglossus aculeatus) (New South Wales), and an Ehrlichia sp. from a single I. fecialis parasitising a quenda (WA). This study highlights the diversity of bacterial genera harboured within wildlife ticks, which may prove to be of medical and/or veterinary importance in the future.