17755 2018 eng 229 6 article 1 2019-02-27 -- -- Wild bees and their nests host Paenibacillus bacteria with functional potential of avail Background: In previous studies, the gram-positive firmicute genus Paenibacillus was found with significant abundances in nests of wild solitary bees. Paenibacillus larvae is well-known for beekeepers as a severe pathogen causing the fatal honey bee disease American foulbrood, and other members of the genus are either secondary invaders of European foulbrood or considered a threat to honey bees. We thus investigated whether Paenibacillus is a common bacterium associated with various wild bees and hence poses a latent threat to honey bees visiting the same flowers. Results: We collected 202 samples from 82 individuals or nests of 13 bee species at the same location and screened each for Paenibacillus using high-throughput sequencing-based 16S metabarcoding. We then isolated the identified strain Paenibacillus MBD-MB06 from a solitary bee nest and sequenced its genome. We did find conserved toxin genes and such encoding for chitin-binding proteins, yet none specifically related to foulbrood virulence or chitinases. Phylogenomic analysis revealed a closer relationship to strains of root-associated Paenibacillus rather than strains causing foulbrood or other accompanying diseases. We found anti-microbial evidence within the genome, confirmed by experimental bioassays with strong growth inhibition of selected fungi as well as gram-positive and gram-negative bacteria. Conclusions: The isolated wild bee associate Paenibacillus MBD-MB06 is a common, but irregularly occurring part of wild bee microbiomes, present on adult body surfaces and guts and within nests especially in megachilids. It was phylogenetically and functionally distinct from harmful members causing honey bee colony diseases, although it shared few conserved proteins putatively toxic to insects that might indicate ancestral predisposition for the evolution of insect pathogens within the group. By contrast, our strain showed anti-microbial capabilities and the genome further indicates abilities for chitin-binding and biofilm-forming, suggesting it is likely a useful associate to avoid fungal penetration of the bee cuticula and a beneficial inhabitant of nests to repress fungal threats in humid and nutrient-rich environments of wild bee nests. Microbiome 10.1186/s40168-018-0614-1 urn:nbn:de:bvb:20-opus-177554 Microbiome (2018) 6:229. DOI: 10.1186/s40168-018-0614-1 false true CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International Alexander Keller Annette Brandel Mira C. Becker Rebecca Balles Usama Ramadan Abdelmohsen Markus J. Ankenbrand Wiebke Sickel eng uncontrolled 16S metabarcoding eng uncontrolled American foulbrood eng uncontrolled anti-microbial activit eng uncontrolled bacterial genomics eng uncontrolled bioassays eng uncontrolled European foulbrood eng uncontrolled Paenibacterin eng uncontrolled phylogenomics eng uncontrolled bee disease eng uncontrolled pathogen vector Arthropoden (Gliederfüßer) open_access Julius-von-Sachs-Institut für Biowissenschaften Theodor-Boveri-Institut für Biowissenschaften Förderzeitraum 2018 Universität Würzburg https://opus.bibliothek.uni-wuerzburg.de/files/17755/Keller_Microbiome.pdf