Development and utilisation of a medium to isolate phenanthrene-degrading Pseudomonas spp.

In this study, we isolated phenanthrene degraders belonging to Pseudomonas spp. by combining the selective force of two previously described media. Th e two compounds, sodium lauryl sarcosine and trimethoprim, from the Gould S 1 medium, were added to minimal agar plates sprayed with phenanthrene. Pseu domonas spp. that could produce clearing zones were isolated in one step fr om the rhizosphere without first selecting for Pseudomonas spp. and subsequ ently screening for degraders or vice versa. Enumeration and isolation of P seudomonas spp. attached to the rhizosphere showed clear differences betwee n two types of soil. Rhizosphere-attached phenanthrene degraders (from Pseu domonas spp.) were isolated from a former coal gasification site, but were absent in an agricultural soil subjected to organic farming. We isolated 23 phenanthrene degraders producing clearing zones from the rhizosphere of ba rley roots. All of these 23 isolates (of which 16 were fluorescent in UV li ght) proved to be members of the Pseudomonas RNA homology group I, on the b asis of results of the analytical profile index (API) test system and class ic taxonomic tests.