Enzymes can reduce toxicity

Naturally occurring soil bacteria contain enzymes which can reduce toxic chemicals to harmless compounds.

"There is no single enzyme that will break down every one of the agrochemicals," says Dr Russell, CSIRO. "Each chemical or group of chemicals needs its own enzyme. But we believe that there is a bacterium for practically every organic pollutant," she says.

A team of scientists from CSIRO Entomology, CSIRO Molecular Science and Orica Australia have isolated enzymes to bio-degrade organophosphates, carbaryl, many synthetic pyrethroids and endosulfan, insecticides which are used widely in agriculture.

"First the enzyme has to be identified," says Dr Russell. "Then it is a process of isolating the enzyme within the bacterium and cloning it into a common bacterium such as E.coli, which can in turn be reproduced in large quantities. Once there is sufficient volume, the E.coli is killed off, the enzymes which have been produced by the bacterium are collected and applied to the contaminated water.

"Alternatively, if the yield of enzyme is high enough, we can produce the enzyme by growing the natural bacterium from which we isolated the enzyme in the first place. Either way, we will need to follow all the necessary regulatory requirements before we trial our enzymes in the field."

The team is now attempting to isolate enzymes for commonly used herbicides such as thiobencarb and molinate. The project is supported by Horticulture Australia Limited, the Australian Cotton Cooperative Research Centre, the CRC for Sustainable Rice Production, the Cotton Research and Development Corporation and the Rural Industries Research and Development Corporation.