The human-associated bacterium Propionibacterium acnes as a grapevine endophyte

Animals and plants have established a long-lasting cohabitation with a variety of microbes, including pathogens, commensals and beneficials. Studies investigating such associations documented numerous cases of bacterial host switches (usually from domestic animals to humans). The exchange of microbial symbionts between humans and plants is much less investigated. We reported a surprising example of horizontal interkingdom transfer of the human opportunistic pathogen (P. acnes) to grapevine (Vitis vinifera L.). P. acnes was interestingly most common inside the plant's pith tissue. Phylogenetic and population analyses place that the establishment of the grapevine-associated P. acnes likely during the Neolithic, when grapevine was domesticated. The endophytic subspecies of P. acnes was named P. Zappae. An analysis of Propionibacteria in the grapevine endosphere showed that P. Zappae is far from being the only species present in this plant as an endophyte