RESULTS
PAH utilization. Twenty-three bacteria able to form clearing zones on BH agar plates coated with naphthalene or phenanthrene(designated PAH1 strains) were isolated. Experiments with BH liquid cultures confirmed their capacity to grow on these PAHs as sole substrates. All PAH1 bacteria formed blue-indigo colonies on indole-containing plates, indicating the presence of naphthalene dioxygenase activity. Biosurfactant-producing reference strains UG2 and PG201 did not clear PAH-sprayed plates or convert indole to indigo. All PAH1 strains were fluorescent pseudomonads.