Bugs that eat cancer-causers

An Australian scientist has discovered a remarkable group of microbes that will destroy some of the worst cancer-causing substances in the polluted modern urban environment and help save lives.

Professor Megh Mallavarapu of CRC CARE and the University of South Australia has identified native Australian soil bacteria which destroy a group of chemicals known as BTEX which has been linked to cancer, nerve damage and other diseases in humans.

“Fuel leaks are one of the most widespread forms of contamination in Australia and elsewhere,” Megh explains. “Former service station sites, fuel farms, garages, workshops, gasometers, oil spills, dry cleaners and factories which used or processed hydrocarbons or explosives are literally everywhere that has been closely settled for the past century or so."

At the 5th World Congress of Environmental Toxicology and Chemistry (SETAC) , he explained that in the course of his research into groundwater contaminated by petroleum and oil spills, he identified a number of indigenous soil bacteria that appear highly tolerant to BTEX — the deadly volatile organic compounds benzene, toluene, ethyl-benzene and xylene.

Of these, benzene is a known carcinogen, and the other three can have serious effects on the central nervous system. Besides polluting water and soil, these chemicals can sometimes emerge from the ground as vapours, being inhaled by people living and working in the vicinity. They are also present in the exhaust fumes of motor vehicles. Together, BTEX form one of the commonest and most hazardous forms of pollution affecting Australian cities and regional areas.

But under appropriate conditions, Megh’s bugs chew them up for breakfast, rendering them completely harmless.

Bacteria which can tolerate BTEX have been identified in other parts of the world, but these are the first from Australia to show a specific preference for dining on these hazardous wastes. The microbes devour the carbon in the BTEX molecules, breaking the rest down into simple and harmless constituents of carbon dioxide and water: “You just add the bacteria to BTEX-contaminated water and they go straight to work ...”

However, Megh and his team have taken the work an important stride further, isolating and sequencing the actual genes in the bacteria which degrade BTEX. Knowing what genes to look for will help in widening the search for more kinds of soil organisms which have a preference for dining on toxins, or identifying strains which do so even more efficiently. This will help expand the suite of organisms available to deal with pollution under different environmental and climate conditions, or with differing mixes of contaminants.

“We’re looking for pilot projects with industry,” he says. “The reason is that no two contaminated sites are the same — the soils, the groundwater, the temperature, the mix of contaminants are always different. We want to see how the bugs perform in as wide a range of conditions as possible.

“We have proved that this technology works in the laboratory. We know the bugs can be used to detect and break down BTEX efficiently. We now want to take them to the next stage and develop the technology for practical application in industry or any urban setting.”

Widespread use of the technology to clean up a century’s worth of contamination from oil spills could make an appreciable contribution to lowering one of the major identified health risks facing people who live and work in cities and industrial areas, he says.