Diversity of anaerobic microbial processes in chlorobenzoate degradation: Nitrate, iron, sulfate and carbonate as electron acceptors

The utilization of monochlorobenzoate isomers (2-, 3- and 4-chlorobenzoate) by anaerobic microbial consortia in River Nile sediments was systematically evaluated under denitrifying, Fe-reducing, sulfidogenic and methanogenic conditions. Loss of all three chlorobenzoates was noted in denitrifying cultures; furthermore, the initial utilization of chlorobenzoates was fastest under denitrifying conditions. Loss of 3-chlorobenzoate was seen under all four reducing conditions and the degradation of chlorobenzoates was coupled stoichiometrically to NO _inf3 ^sup- loss Fe²⁺ production, SO _inf4 ^sup2- loss or CH₄ production, indicating that the chlorobenzoates were oxidized to CO₂. To our knowledge, this is the first observation of halogenated aromatic degradation coupled to Fe reduction.