ANAEROBIC DEGRADATION OF HALOGENATED BENZOIC-ACIDS COUPLED TO DENITRIFICATION OBSERVED IN A VARIETY OF SEDIMENT AND SOIL SAMPLES

Denitrifying enrichment cultures utilizing monochlorinated benzoic aci ds as a carbon source were established using sediments and soils from a variety of sources as inocula. Enrichment cultures from most of the sites readily degraded 3- and 4-chlorobenzoate within 2-4 weeks. Upon refeeding, 3- and 4-chlorobenzoate were rapidly depleted, and stable d enitrifying cultures were obtained by repeated dilution and refeeding of the substrates. 2-Chlorobenzoate, however, was only slowly metaboli zed and this activity was only observed in a few sites. Denitrifying c onsortia were maintained on either 3- or 4-chlorobenzoate as the sole source of carbon and energy and chlorobenzoate utilization was depende nt on denitrification. These cultures were also capable of utilizing t he corresponding brominated and iodinated benzoic acids, but the activ ity was specific to the position of the halogen substituent. Removal o f halogen was stoichiometric, indicating that dehalogenation occurred at some step in metabolism.