of the 8 plates exposed to 2 6 dmn a total of 21 colonies were red all of these were picked and purified each of the 8 plates exposed to 2 methylnaphthalene had about 200 red colonies about 250 of these were picked and purified when grown on medium containing no ttc it was evident by the yellow or brown colors produced that many of these microorganisms could cleave the aromatic rings and were therefore considered unsuitable for present purposes and discarded none of the 2 6 dmn exposed isolates exhibited evidence of the colored ring fission products seven of the remaining isolates from the 2 methylnaphthalene exposed plates and all of the isolates from the 2 6 dmn exposed plates were then grown in broth cultures as described in example 1 and analyzed by hplc for the dcn and cmn peaks approximately 15 strains isolated from the 2 6 dmn plates and approximately 9 strains isolated from the 2 mn plates showed evidence of cmn production strain 1028 and strain 1032 isolated from 2 6 dmn and 2 mn plates respectively showed any evidence of dcn production the evidence was subsequently confirmed by gc ms analysis other strains showing cmn production but no apparent dcn production were used in coculture as described below in example 6 the above results indicate that dcn producing strains can effectively and reproducibly be isolated from the sewage samples used the conversion by 1013 p1013 as described in example 1 was carried out with and without 0 005 2 aminobenzoate added to the medium more enzyme was present in the cells exposed to the inducer and in turn the use of inducer resulted in detectable dcn production whereas no dcn production was detected without.