Strains of bacteria have been obtained from samples of soil and sediment by enrichment with dibenzofuran, dibenzothiophene, acridine, carbazole and pyrene. Pure cultures were used to determine the persistence of these compounds in aqueous solutions under aerobic conditions in sealed ampoules. Some strains degraded the substrates totally while others accomplished only partial degradation or biotransformation. Intermediate metabolites were identifiable only from dibenzofuran. Some of the experimental procedures that had to be adopted are discussed and the results of the experiments examined in the wider context of bioremediation