Proteomics‐based identification of orchid-associated bacteria colonizing the Epipactis albensis, E. helleborine and E. purpurata (Orchidaceae, Neottieae)

Using proteomics-based identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), we conducted the first analysis of the composition of endophytic bacteria isolated from different parts of selected Epipactis species, i.e. the buds, the inflorescences and the central part of the shoots, as well as the rhizomes. We identified aerobic and anaerobic bacteria, including such taxa as Bacillus spp., Clostridium spp., Pseudomonas spp. and Stenotrophomonas spp., which may be considered as promoting plant growth. Because most of the indicated bacteria genera belong to spore-producing taxa (spores allow bacterial symbionts to survive adverse conditions), we suggest that these bacteria species contribute to the adaptation of orchids to the environment. We found clear differences in the microbiome between investigated closely related taxa, i.e., Epipactis albensis, E. helleborine, E. purpurata and E. purpurata f. chlorophylla. Some of the analysed orchid species, i.e. E. albensis and E. purpurata co-occur in habitats, and their bacterial microbiomes differ from each other.