Seventeen different plant species grown in sand culture were screened for their ability to release phenolic compounds from their roots. The concentration of phenols in the rhizosphere of each species was compared to concentrations of phenols known to support the growth of PCB-degrading bacteria (Donnelly et al. 1994). It was concluded that the concentration throughout the rhizosphere was below substrate levels, but for some plant species (i.e. mulberry) there was evidence that portions of the rhizosphere possessed levels of phenols sufficiently high enough to support microbial growth.