A bacterium tentatively identified as an Erwinia sp. was isolated from sewage by enrichment on menthanol and lignin. Several mutants developed from this strain were studied for their ability to degrade aromatic ethers. Different concentrations of the chemicals were incubated with the organisms and the degradation was estimated by high-performance liquid chromatography (HPLC). Among these mutants, one isolate, Erwinia sp. strain CU3614, showed resistance to copper ions (>20 mM CuSO4) and the ability to degrade 4-hydroxydiphenyl ether (4-HDPE), 4-chlorodiphenyl ether (4-CDPE), 4-nitrodiphenyl ether (4-NDPE), and 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) in the presence of copper ions. Increased concentrations of copper in the medium resulted in higher degradation of 4-HDPE. Further studies with copper-sensitive mutants obtained from Erwinia sp. CU3614 by Tn5 transposon-induced mutagenesis showed a corresponding decrease in the ability to degrade 4-HDPE. These results suggest the presence of copper-associated activity in the biotransformation of aromatic ethers. (Copyright (c) 1990 Society for Industrial Microbiology.)