Soil-dwelling bacteria can rapidly break down organic contaminants in the environment, and now North American scientists have shown that microbes can clean up polybrominated diphenyl ethers (PBDEs). 

PBDEs are used as fire retardants in a wide range of commercial goods, but many have now been removed from the market in the US and Europe because of their neurotoxic nature. What's more, they tend to fix to soil particles and are very persistent in the environment. Biological degradation of these compounds was previously assumed to be minimal. 

Anne Vonderheide at the University of Cincinnati, Ohio, US, led a cross-disciplinary team of biologists, ecologists, chemists and environmental scientists from the US and Canada, who have shown that mixed bacterial cultures extracted from contaminated soils, can use PBDEs as their sole nutrient source. 'Almost complete loss of the parent compounds took place within a few minutes,' said Vonderheide. 

The speed of the microbial degradation meant that only one of the expected degradation products could be found using a combination of atomic and molecular spectrometry. Vonderheide says further study of the metabolic pathways 'would challenge even the most established and reliable instrumental techniques'. 

Vonderheide's experiments were performed in water, not in soil. In a real environment, she explained, the bacteria would be interacting with different carbon sources, organisms and many other factors that could impact their ability to degrade PDBEs. She noted that more work is needed to evaluate the situation in a natural setting. 

Michael Spencelayh