Bugs give clean sites a glowing recommendation

时间:2019-03-07 05:07:05166网络整理admin

By Andy Coghlan DERELICT industrial land, such as the site of London’s Millennium Dome, is often ideally placed for building new houses or other buildings. The trouble is, the soil at these brownfield sites may be awash with pollutants that have to be identified and removed. Now a Scottish company has the answer: a glowing biosensor that quickly reveals when problem chemicals are present. Remedios, an Aberdeen-based start-up, has developed genetically modified bacteria that glow yellow in samples of clean soil but not in contaminated soil. By progressively removing different kinds of contaminant and retesting, Remedios’s system reveals which pollutants were present in the original sample, allowing the best method for cleaning up the site to be chosen. “It’s like a bacterial canary,” says Anne Glover, the firm’s technical director. Remedios uses eight common soil bacteria, each one genetically modified to produce light when it is in good health. Some have received the lux gene from bioluminescent marine bacteria, while others got the luc gene that codes for luciferase, the enzyme that gives fireflies their glow. The intensity of the bacteria’s glow quickly shows how clean the soil is—though not which chemicals are present. “We’re looking at any biological toxicity affecting microorganisms on the site, or human health,” says Glover, who spent seven years developing the system at the University of Aberdeen. The lab test starts by screening soil samples with a harmless, light-producing strain of Escherichia coli. “This first test indicates total toxicity,” she says. If this shows pollutants are present, the sample is treated to drive off any volatile organic compounds, such as the solvents benzene, toluene and xylene, and tested again. If the bacteria now glow more strongly, these volatiles must have caused at least some of the original pollution. The final stage removes non-volatile toxic organic compounds such as PCBs,