Anaerobic Degradation of Halogenated Benzoic Acids by Photoheterotrophic Bacteria

From light-exposed enrichment cultures containing benzoate and a mixture of chlorobenzoates, a pure culture was obtained able to grow with 3-chlorobenzoate (3-CBA) or 3-bromobenzoate (3-BrBA) as the sole growth substrate anaerobically in the light. The thus isolated organism is a photoheterotroph, designated isolate DCP3. It is preliminarily identified as a Rhodopseudomonas palustris strain. It differs from Rhodopseudomonas palustris WS17, the only other known photoheterotroph capable of using 3-CBA for growth, in its independence of benzoate for growth with 3-CBA and in its wider substrate range: if grown on 3-CBA, it can also use 2-CBA, 4-CBA or 3,5-CBA.