Isolation of A rthrobacter species from the phyllosphere and demonstration of their epiphytic fitness

Bacteria of the genus A rthrobacter are common inhabitants of the soil environment, but can also be recovered from leaf surfaces (the phyllosphere). Using enrichment cultures on 4‐chlorophenol, we succeeded in specifically isolating A rthrobacter bacteria from ground cover vegetation in an apple orchard. Based on 16 S r RNA gene sequencing, the isolates were found to belong to at least three different species of A rthrobacter . Compared to the model bacterial epiphyte P antoea agglomerans , the A rthrobacter isolates performed as well or even better in a standardized laboratory test of phyllosphere fitness. A similar performance was observed with the well‐characterized soil isolate A rthrobacter chlorophenolicus A 6. These findings suggest that the frequently reported presence of A rthrobacter strains on plant foliage can be explained by the capacity to multiply and persist in the phyllosphere environment. As bacteria from the genus A rthrobacter are known for their ability to degrade a wide variety of organic pollutants, their high phyllosphere competency marks them as a promising group for future studies on phyllosphere‐based bioremediation, for example, as foliar bioaugmentation on ground cover or buffer‐zone vegetation to prevent pesticides from reaching soil, surface‐, or groundwater.