Biodegradation of aromatic compounds in the presence of secondary substrates

Experiments were conducted to examine the biodegradability of three aromatic compounds typically found at groundwater contamination sites; benzene, toluene, and chlorobenzene. A pure Pseudomonas species, JS6, was used in all batch experiments. JS6 was grown on benzene, chlorobenzene, toluene, yeast extract, or glucose as sole source of carbon and energy. These cultures were in turn used to test the biodegradability of the three aromatics of interest both in the presence and absence of the chemical used for acclimation. The results indicated that the presence of a non-aromatic substrate (yeast extract or glucose) enhanced the biodegradation of the aromatic compound of interest. Results also indicated JS6 has the ability to simultaneously degrade two aromatic compounds when the following mixtures were tested; toluene and benzene, toluene and chlorobenzene, and chlorobenzene and benzene. Enzyme induction experiments confirmed that the enzymes required for the initial breakdown of the aromatic compounds tested are inducible, not constitutive.