Use of a bromobenzoate for cross-adaptation of anaerobic bacteria in Lake Ontario sediments for degradation of chlorinated aromatics

The capacity of anaerobic micro-organisms in the sediment of a freshwater lake to degrade halogenated benzoates was investigated. Sediments collected from Lake Ontario along the Toronto waterfront (Ontario, Canada) were incubated with halogenated benzoates and dehalogenation was measured by high pressure liquid chromatography (HPLC). Following adaptation to monohalogenated benzoates (3-bromobenzoate, 3-chlorobenzoate), cross-adaptation to complex halogenated aromatics (3,5-dichlorobenzoate, 4-amino-3,5-dichlorobenzoate), was assessed by monitoring their depletion by HPLC. Prior adaptation to 3-bromobenzoate resulted in a more rapid depletion of the complex halogenated aromatics (3,5-dichlorobenzoate and 4-amino-3,5-dichlorobenzoate) than prior adaptation to 3-chlorobenzoate. The results suggest that cross-adaptation may be an approach to a more rapid biodegradation of complex pollutants in lake sediments or in wastewater treatment systems, with the 3-bromobenzeate preferred over the 3-chlorobenzoate as the adaptation substrate.