Genetic engineering offers environmental benefits

Researchers at the University's Department of Chemistry are conducting research into genetically engineered bacteria that could cleanse dangerous chemicals from the environment. The group, led by Dr Luet-Lok Wong (pictured left), University Lecturer in Inorganic Chemistry and Fellow of St Hugh's College, have modified a gene from Pseudomonas putida, a common soil bacterium, to make an enzyme which attacks three soil pollutants: 1,2-dichlorobenzene, 1,3,5-trichlorobenzene, and pentachlorobenzene. These chlorobenzenes are used as solvents in the chemical industry and as raw material for making pesticides and herbicides, and are major contaminants of the soil in industrial `brownfield' sites. They could previously only be removed by incinerating the topsoil, which is a costly procedure. The modification is based on the fact that chlorophenols, which are chemically related to the pollutant chlorobenzenes, are quickly destroyed by common soil bacteria. The group is working in collaboration with Dr Mark Bailey and Dr Ian Thompson at the University's NERC Institute of Virology and Environmental Microbiology to develop genetically engineered bacteria with a modified enzyme which has had key amino acids replaced with bulkier alternatives. This enzyme will be capable of converting any of the three chlorobenzenes to the chlorophenols, which can then be degraded by ordinary soil bacteria. The team hopes to engineer the system further to make it attack common, highly hazardous pollutants such as cancer-causing dioxins, PCBs, and benzopyrenes. Environmental groups such as Gene-Watch UK and Greenpeace have already expressed support for the approach and back further work to prime the enzyme to attack dioxins and PCBs. Dr Wong said: `Cleaning up brownfield sites is an important step in urban regeneration. This new method of targeting engineered enzymes to convert hazardous pollutants to reactive compounds which are easily degraded could also help other indigenous degradative bacteria to thrive and therefore speed up the cleaning up process. There is a long way to go yet.'