Effect of copper ion and soil humic acid on biodegradation of decabromodiphenyl ether (BDE-209) by Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a good environmental microorganism capable of degrading decabromodiphenyl ether (BDE-209). This paper studied the effect of Cu2+ and humic acid (HA) extracted from e-waste contaminated soils on biodegradation of BDE-209 by P. aeruginosa. The adsorption isotherms of Cu2+ on HA, the crude enzyme activity, cell surface morphology, and biodegradation pathway were also investigated. The results showed that BDE-209 biodegradation by P. aeruginosa was inhibited at Cu2+ concentrations above 5 mg L-1 , but exhibited the best effect at the condition of 40 mg L-1 Cu2+  + 3 g L-1 HA. At the condition of 40 mg L-1 Cu2+  + 3 g L-1 HA, 97.35 ± 2.33% of the initial BDE-209 was degraded after 5 days, debromination efficiency was 72.14 ± 1.89%, crude enzyme activity reached the maximum of 0.519 ± 0.022U g-1 protein, cell surface of P. aeruginosa was smooth with normal short-rod shapes, and biodegradation pathway mainly include debromination, hydroxylation, and cleavage of the diphenyl ether bond. It was suggested that soil HA could eliminate the toxic effect of high Cu2+ concentrations and biodegradation of BDE-209 was improved by synergistic effect of HA and Cu2+ .