Phylogenomic analysis of the genus Rosenbergiella and description of Rosenbergiella gaditana sp. nov., Rosenbergiella metrosideri sp. nov., Rosenbergiella epipactidis subsp. epipactidis subsp. nov., Rosenbergiella epipactidis subsp. californiensis subsp. nov., Rosenbergiella epipactidis subsp. japonicus subsp. nov., Rosenbergiella nectarea subsp. nectarea subsp. nov. and Rosenbergiella nectarea subsp. apis subsp. nov., isolated from floral nectar and insects

Abstract

The genus Rosenbergiella is one of the most frequent bacterial inhabitants of flowers and a usual member of the insect microbiota worldwide. To date, there is only one publicly available Rosenbergiella genome, corresponding to the type strain of Rosenbergiella nectarea (8N4^T), which precludes a detailed analysis of intra-genus phylogenetic relationships. In this study, we obtained draft genomes of the type strains of the other Rosenbergiella species validly published to date (R. australiborealis, R. collisarenosi and R. epipactidis) and 23 additional isolates of flower and insect origin. Isolate S61^T, retrieved from the nectar of an Antirrhinum sp. flower collected in southern Spain, displayed low average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values when compared with other Rosenbergiella members (≤86.5 and ≤29.8 %, respectively). Similarly, isolate JB07^T, which was obtained from the floral nectar of Metrosideros polymorpha plants in Hawaii (USA) had ≤95.7 % ANI and ≤64.1 % isDDH with other Rosenbergiella isolates. Therefore, our results support the description of two new Rosenbergiella species for which we propose the names Rosenbergiella gaditana sp. nov. (type strain: S61^T=NCCB 100789^T=DSM 111181^T) and Rosenbergiella metrosideri sp. nov. (JB07^T=NCCB 100888^T=LMG 32616^T). Additionally, some R. epipactidis and R. nectarea isolates showed isDDH values<79 % with other conspecific isolates, which suggests that these species include subspecies for which we propose the names Rosenbergiella epipactidis subsp. epipactidis subsp. nov. (S256^T=CECT 8502^T=LMG 27956^T), Rosenbergiella epipactidis subsp. californiensis subsp. nov. (FR72^T=NCCB 100898^T=LMG 32786^T), Rosenbergiella epipactidis subsp. japonicus subsp. nov. (K24^T=NCCB 100924^T=LMG 32785^T), Rosenbergiella nectarea subsp. nectarea subsp. nov. (8N4^T = DSM 24150^T = LMG 26121^T) and Rosenbergiella nectarea subsp. apis subsp. nov. (B1A^T=NCCB 100810^T= DSM 111763^T), respectively. Finally, we present the first phylogenomic analysis of the genus Rosenbergiella and update the formal description of the species R. australiborealis, R. collisarenosi, R. epipactidis and R. nectarea based on new genomic and phenotypic information.

Keywords: Rosenbergiella; floral nectar; insect; phylogenomics; taxonomy.