Chlorobenzene Degradation by Bacteria Isolated from Contaminated Groundwater

Bacterial isolates were obtained from groundwater and soils contaminated with chlorobenzene (CB). The isolates were tested to determine whether the natural community could remove the groundwater contaminants. These isolates were identified and characterized as to their ability to grow on CB and related aromatic compounds. The complete consortium could mineralize approximately 54% of the CB within 7 days, with no accumulation of 3-chlorocatechol. Metabolic pathways were evaluated for several isolates. One phenotype was characterized by the ability to degrade CB by the modified ortho pathway. One strain also degraded p-dichlorobenzene by using the same pathway. Isolates exhibiting a second phenotype degraded p-cresol, benzene, and phenol by the classical ortho pathway and accumulated 3-chlorocatechol when grown in the presence of CB. Strains of the third phenotype grew on complex media in the presence of CB but did not transform any of the aromatic compounds tested. The results suggest that the indigenous microbial community at the contaminated site would be able to degrade CB if provided with the appropriate conditions.