AUSTRALIA: more efficient Atrazine-eating bug found

The microbe was identified from a polluted site in Perth by University of WA PhD researcher Ms Amanda Tilbury, working with microbiologist Dr Peter Franzmann of CSIRO Land and Water.

The microbe is a new strain of the well-known soil organism Pseudomonas.

More than 300 tonnes of atrazine are sprayed on broadleaf and grassy weeds on farms and in cities across Australia. It is highly persistent and can persist in the soil or water for years afterwards. Although listed as a possible human carcinogen, the main problem with atrazine is that it is highly toxic to water life. It has been implicated in a number of fish kills.

“It can also get into groundwater, and in some parts of the country groundwater is used for drinking – so we wanted to find a way of purifying the water while it was still underground,” Ms Tilbury explains.

Examining soil from a site contaminated with atrazine in the Perth metropolitan area, she found at least 40 different kinds of bacteria. From these she selected four which appeared to have the ability to digest and neutralise the pollution. The standout strain, Pseudomonas AT2 (initialled after Amanda Tilbury), had the three vital genes that enable it to break down atrazine in a matter of hours.

“Normally the atrazine would have a half-life in the groundwater as long as 8 years. In the laboratory, we reduced this to just five hours using AT2,” she says. “We hope to be able to spray or inject AT2 into any big spill or contamination by atrazine and so render it harmless. It may also be used to clean a farmer’s soil so the atrazine residue has no effect on the next crop sown in the paddock.”