Aerobic biotransformation of decabromodiphenyl ether (PBDE-209) by Pseudomonas aeruginosa

Aerobic biodegradation of decabromodiphenyl ether (PBDE-209) by Pseudomonas aeruginosa under the influence of co-metabolic substrates and heavy metal cadmium ion was studied, The results showed that certain amount of co-metabolic substrates, such as glucose, sucrose, lactose, starch, and beef extract, would promote the biodegradation of PBDE-209, among which glucose most favorably accelerated PBDE-209 degradation by about 36% within 5d. The highest degradation efficiency was reached at the ratio of PBDE-209 and glucose 1:5 while excessive carbon source would actually hamper the degradation efficiency. Exploration of influences of cadmium ion on PBDE-209 biodegradation indicated that degradation efficiency was stimulated at low concentrations of Cd(2+) (0.5-2 mg L(-1)) while inhibited at higher levels (5-10 mg L(-1)), inferring that the heavy metals of different concentrations possessed mixed reactions on PBDE-209 bioremoval. Bromine ion was produced during the biotransformation process and its concentration had a good negative correlation with the residues of PBDE-209. Two nonabromodiphenyl ethers (PBDE-208, PBDE-207), four octabromodiphenyl ethers (PBDE-203, PBDE-202, PBDE-197, PBDE-196) and one heptabromodiphenyl ethers (PBDE-183) were formed with the decomposition of PBDE-209, demonstrating that the main aerobic transformation mechanism of PBDE-209 was debromination.