Rickettsia bacterial diversity detected by Targeted and SRA screens
The targeted Rickettsia screen of 1,612 individuals from 169 invertebrate species detected infections in 16 species (9.47%) including both aquatic and terrestrial taxa (Table 1). Of these, 14 profiles clustered within the Torix group with the remaining two placed in the Belli and Rhyzobius groups (Figure 5). Comparisons of TorixRickettsia frequency between aquatic/semiaquatic vs terrestrial arthropods revealed evidence for a higher representation of TorixRickettsia infected species in the aquatic biome (Fisher’s Exact,P = 0.019).
During the SRA search, phyloFlash flagged 29 Rickettsia sequences in the groups: Bellii (n=12), Torix (n=8), Transitional (n=6), Rhyzobius (n=2), and Spotted Fever (n=1) (Figure 5). In addition, Kraken identified nine Rickettsia -containing arthropod SRA datasets missed by phyloFlash. Two of these were from the Torix group, in phantom midge hosts (Diptera: Chaobaridae: Mochlonyx cinctipes andChaoborus trivitattus ), with the remaining seven placed in Belli and Spotted Fever groups (Table S3). The search of NCBI revealed 11 deposits ascribed to host mtDNA that were in fact TorixRickettsia sequences (Table S9 and Figure S2).