|CSIRO | SOLVE | Issue 12 | Aug 07|
Blowies Inspire Pesticide Attack
By Melissa Marino
Blowfly maggots and dog-wash play starring roles in the story of a remarkable environmental clean-up technology.
The blowfly and the merino are familiar elements within the Australian landscape, and are also pitched in mortal battle. Blowfly maggots laid in the merino’s loose, folding skin cause an often fatal bacterial infection – and all attempts to find a prophylactic have failed.
Blowfly maggots have proved to be extremely resilient to chemical attack. While this trait is frustrating to wool growers, it started CSIRO researcher John Oakeshott wondering if this extraordinary resistance could be harnessed; if the biological mechanisms that enabled these seemingly primitive creatures to resist even the most powerful chemicals could be turned against problem pesticides lodged in the environment. This
Bioremediation has become the science behind this development – a natural product that breaks down and neutralises pesticides. It is based on an enzyme that the maggots use to consume and degrade organophosphates.
That product, Landguard™, developed by CSIRO Entomology’s bioremediation team with commercial partner Orica Watercare, is now used around Australia to remove pesticides from irrigation run-off, from spray equipment and from water contaminated during sheep-dipping (a practice used to protect sheep from lice).
Landguard™ has also just been launched in the UK where it is being used to eliminate pesticide from used sheep-dip. Another major market is emerging in California, where it is being enlisted to protect San Francisco’s water supply by remediating pesticides feeding into the system from irrigation run-off upstream.
Orica Watercare commercial manager Kate Dawson says Landguard™ is cost-effective and rapid in neutralising widely used organophosphate-based pesticides. “For example, in sheep-dipping in the UK and Australia, Landguard™ reduces the toxicity by more than 200,000 times, and it reduces the life of residual byproducts to less than a week,” she says. “Usually, residues would last a number of months. For both livestock dip and irrigation run-off, you’re looking at more than 99.99 per cent breakdown of the pesticide.”
Ms Dawson says pesticides from irrigation run-off are generally broken down within five minutes of treatment. Used sheep-dip is decontaminated within 40 minutes and rinse water from spray tanks, overnight. “Basically, it’s for use anywhere where organophosphates are used and it helps a farmer avoid any contamination downstream,” she says. “It saves contaminated water from entering sensitive areas such as home gardens, stock areas and waterways that are used for swimming, water supplies and recreational fishing.”
Dr Robyn Russell, CSIRO Environmental Biotechnology and Enzymology research leader, was there in 1987 when work began on the blowfly enzyme, and then several years later for the first breakthrough. Along with Dr Oakeshott, she and their team isolated the mutant enzyme responsible for giving blowflies the ability to consume and degrade organophosphates and through genetic cloning technology, recreated it in bacteria.
But after the initial success, they soon realised that they would have to look further afield. “It doesn’t take much organophosphate to kill an insect, so the enzymes that evolved in insects wouldn’t have to degrade very high concentrations of pesticides and wouldn’t have to do it that fast to protect the insect,” Dr Russell says.
In 1998, the team set out to find another enzyme, one that could work fast enough to attack high concentrations of organophosphates effectively. They started digging up soil samples from land affected by pesticides, and again found their culprit out of left field. The best specimen came not from a farm, but from the back yard of the family of a researcher who bred dogs.
Dog-wash had been tipped out in the same spot in the back yard over several years, creating an enzyme in the soil bacteria that mutated to feed on insecticide in the dog-wash, breaking it down and eliminating it from the environment. When the enzyme was brought back to the lab, isolated and analysed, the researchers discovered it was effective against about 70 per cent of organophosphates on the market. It was also fast working and hardy in a range of conditions.
“One molecule of this enzyme would degrade thousands of molecules of the organophosphate per second, so it was a huge discovery,” Dr Russell says. “You could put the enzyme out in the mud, in the dirt, in irrigation water and it still worked, it happily chomped away, so it’s lucky we found it because not all enzymes are as stable.”
Bacterial cultures developed through cloning the genes that encode the enzyme were then delivered to Orica Watercare to build up for commercialisation, and after just two years in the market, it is making its mark. The potency the enzyme showed in the lab is being reflected in the field, with just 100 grams of the powder-like product required to treat one megalitre of water.
As well as agricultural applications, Ms Dawson says the product is also being used in broader markets, for example on golf courses, where it is used to decontaminate spraying equipment and its rinse water. It is also applied effectively as an occupational health and safety tool, she says, on-farm or in other associated industries to clean up chemical spills.“This is a world-first product where you use then degrade the pesticide, with minimal effect on the environment,” Ms Dawson says.
A world-first product that degrades pesticides with minimal effect on the environment.
Landguard™ is used to remove pesticides from irrigation run-off, spray equipment and water contaminated during sheep-dipping around Australia.
IN THIS ISSUE
|Home | About Us | eSubscribe | Links|