Characterization of gut symbionts from wild-caught Drosophila and other Diptera: description of Utexia brackfieldae gen. nov., sp. nov., Orbus sturtevantii sp. nov., Orbus wheelerorum sp. nov, and Orbus mooreae sp. nov.

Non-culture based surveys show that the bacterial family <i>Orbaceae</i> is widespread in guts of insects, including wild <i>Drosophila</i>. Relatively few isolates have been described, and none has been described from <i>Drosophila</i>. We present the isolation and characterization of five strains of <i>Orbaceae</i> from wild-caught flies of the genera <i>Drosophila</i> (Diptera: Drosophilidae) and <i>Neogriphoneura</i> (Diptera: Lauxaniidae). Cells are generally rod-shaped, mesophilic, and measure 0.8-2.0 µm long by 0.3-0.5 µm wide. Optimal growth was observed under ambient atmosphere. Reconstruction of phylogenies from the 16S rRNA gene and from single-copy orthologs verify placement of these strains within <i>Orbaceae</i>. Cells exhibited similar fatty acid profiles to those of other <i>Orbaceae</i>. Strain lpD01^T shared 74% average nucleotide identity (ANI) with its closest relatives <i>Ca.</i> Schmidhempelia bombi Bimp and <i>Zophobihabitans entericus</i> IPMB12^T. Results from multiple genome-wide similarity comparisons indicate lpD01^T should be classified as a novel species within a novel genus. The major respiratory quinone for lpD01^T is ubiquinone Q-8. lpD02^T, lpD03, lpD04^T, and BiB^T are more closely related to <i>Orbus hercynius</i> CN3^T (76, 77, 76, and 77% ANI, respectively) than to other described <i>Orbaceae</i>. Genomic and phylogenetic analyses suggest that lpD03 and lpD04^T belong to the same species and that lpD02^T, lpD03/lpD04^T, and BiB^T are each novel species of the genus <i>Orbus</i>. The proposed names of these strains are <i>Utexia brackfieldae</i> gen. nov., sp. nov. (type strain lpD01^T =NCIMB 15517^T =ATCC TSD-399^T), <i>Orbus sturtevantii</i> sp. nov (type strain lpD02^T =NCIMB 15518^T =ATCC TSD-400^T), <i>Orbus wheelerorum</i> sp. nov. (type strain lpD04^T =NCIMB 15520^T =ATCC TSD-401^T), and <i>Orbus mooreae</i> sp. nov (type strain BiB^T=NCIMB 15516^T =ATCC TSD-402^T). The isolation and characterization of these strains expands the repertoire of culturable bacteria naturally associated with insects, including the model organism <i>D. melanogaster</i>.