Dioxins and dioxin-like compounds, including PCDDs, PCDFs and PCBs, are persistent organic pollutants (POPs) that are resistant to environmental degradation. However, POPs can be degraded by certain microorganisms with acquisition of a novel set of enzymes, such as biphenyl degradation by Paraburkholderia xenovorans LB400 involving four novel enzymes encoded in operon-like structures [MD:
M00543]. DDT, another POP, and carbazol are also known to be degraded in similar pathways.