The return of the benzene eaters

A study by scientists at Southern Illinois University (Carbondale) has led to an important discovery that could help remove a highly toxic chemical from the environment.

Benzene, a major component of gasoline and other petroleum-based fuels, is one of the most common contaminants found in groundwater supplies. Long-term exposure to benzene can lead to cancer in humans.

Although benzene is readily biodegraded when exposed to the atmosphere, removing the compound from airless environments is much more difficult.

Now, however, researchers at SIUC, led by John D. Coates, an assistant professor of microbiology, have isolated two micro-organisms that can break down benzene without the aid of oxygen.

'Not only is benzene a problem in underground water supplies, it can be found in soils and sediments,' Coates said. 'Fuel spills and leaking underground storage tanks are the main culprits.'

Coates says the organisms, known as Dechloromonas strain RCB and Dechloromonas strain JJ, were found to oxidize benzene to carbon dioxide without the help of oxygen.

'One of the big problems in contaminated environments is a lack of oxygen,' Coates said. 'Without oxygen, the biodegradation of benzene essentially slows to a crawl. These organisms are able to speed up the process. What once took 70 days now takes place in seven days.'

Where can these organisms be found? According to Coates, just about everywhere.

'They've been found in a broad range of environments,' Coates noted. 'We've found them in soil samples taken from around the University and in samples taken from the Antarctic.'

While Coates' discovery could have major implications for environmental remediation, there are a host of other applications.

'This study provides the first example of an organism of any type that can oxidize benzene anaerobically,' Coates said. 'For many years, the ability of micro-organisms to degrade benzene in the absence of oxygen has been controversial because of the chemical stability of this compound.

'With these organisms in hand, we can now get a better understanding of how micro-organisms can tackle this problem,' Coates continued. 'This is encouraging news for other researchers who are doing similar work.'