Protozoa detect water toxins

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Woods Hole Oceanographic Institution (WHOI) biologist Scott Gallager has grand plans for his revolutionary Swimming Behavioural Spectrophotometer (SBS), which employs one-celled protozoa to detect toxins in water sources. The SBS has been selected as a 2010 ‘Better World\' technology by the Association of University Technology Managers.

This success story was actually a concept which the US Department of Defense (DOD) put on the back burner for a year and a half, before finally funding Gallager's idea to detect toxins in water sources using the smallest of animals (the one-celled protozoa). Gallagher is currently working on streamlining the contraption, which will eventually evolve into a computer chip. The SBS may now be on the cusp of providing unprecedented assessment of the world's water supplies.

The groundbreaking technique works by introducing protozoa into small chambers with water samples taken from municipal, industrial or military water sources and comparing them to control samples. Any alteration of the protozoa's swimming mechanics is a sign that water conditions have changed and chemical or biological contaminants (e.g. pesticides, industrial chemicals or biological warfare agents) may be present.

A camera records the protozoa's swimming patterns, triggering software developed by Gallager and his colleagues that interprets the water's risk. The device then relays colour-coded, traffic light-type signals to the user: green (safe); yellow (check the water further for safety); red (bad or deadly: do not drink the water). Further analyses of the swimming patterns, along with the water's acidity levels and other variables, can help scientists determine the presence of specific kinds of toxins including pesticides and heavy metals such as cadmium or mercury. The system includes controls to prevent the reporting of false-positive and false-negative results.

The big advantage of the SBS is that it provides virtually instantaneous feedback on the water supply's safety, Gallager says. 'It's a very rapid approach to providing a continuous monitoring for the potential presence of toxins,' he says.

Gallager hatched the plan along with former WHOI colleague Wade McGillis (now a professor at Columbia University's Lamont-Doherty Earth Observatory) while examining the possible effects of climate change on microscopic plankton. Their premise was that protozoa, with their unique methods of propelling themselves through water, might act as barometers of the health of their local underwater environment.

After the 9/11 attacks in 2001, McGillis told Gallager that the Defense Department was interested in techniques for monitoring water supplies. Gallager submitted his protozoa proposal to DOD in 2002; 'I didn't hear back,' he said. 'I literally forgot about it.' The following year, he received an e-mail from the Defense Department. 'It simply said: ‘How do you want us to transfer the funds?'' he recalled. 'It was nearly a million dollars.'

Today Gallager is working on his brainchild for both WHOI and Petrel Biosensors Inc., a private company that has licensed the technology for further development and commercialisation. The company is attempting to raise about USD2 million to further develop and fine-tune the SBS.

'Other existing water tests with this spectrum of activity take from 24 to 72 hours to generate results and can cost anywhere from USD50 to USD250 per test,' says Bob Curtis, Petrel's chief executive officer. 'We estimate that the SBS will perform real-time biological testing and provide nearly instant feedback for just USD1 or USD2 per test.'

Commercial applications for the technology include monitoring of industrial wastewater discharge, security and quality of drinking water supplies and the potential testing of water sources associated with hydraulic fracturing (fracking) in the oil and gas industry.

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