Microbial degradation of endocrine-disrupting organic compounds and environmental residues of pharmaceutical compounds
GU Ji-Dong, WANG Ying-Ying (Laboratory of Environmental Toxicology, Department of Ecology & Biodiversity, The University of Hong Kong, Pokfulam Road, Hong Kong SAR)
Synthetic organic pollutants are not only toxic and accumulative but also able to induce malformation and mutation. Contamination of synthetic compounds in environment disrupts the endocrine system in organisms including human beings. Developed countries have established regulations to limit and control the amount of these compounds in water and food chain. It is clearly known that some herbicides and insecticides (e.g. atrazine and DDT), and plasticizers are all endocrine-disrupting organics, which have adverse effect on the normal development of organisms. These compounds, however, present widely in the environment. The concentration could be extremely high under special circumstance. For example, as high as 10 g · L-1 of phthalic acid and dimethyl phthalate ester (DMPE) were found in landfill leachate. According to our investigation on microbial degradation of phthalic acid and DMPE, enrichment culture obtained from activated sludge and mangrove can mineralize this kind of compounds within short period of time. It is also found that single bacterial species is not able to completely degrade DMPE. Consortium of two or three pure species could mineralize DMPE at a concentration of 500 mg·L-1 within one week. Two degradation intermediates were isolated and identified, and degradation pathway has been established in our investigation. It has been approved that environmental hormone such as DMPE could be mineralized by microorganisms. On the other hand, environmental residues of pharmaceutical compounds are an emerging problem and more attention should be paid to conduct research in this field.