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R&D News: Bio-Based Arsenic Sensors

Recently, “Forschung Aktuell”, a science news radio show on Deutschland Radio, highlighted some interesting research by the German scientist Hauke Harms on his approach to affordable solutions to detect arsenic in drinking water which is a common problem in some parts of the world.

I was interested to learn how arsenic is sometimes found in drinking water. According to the show, arsen naturally exists in the environment as arsenopyrite. Natural processes can erode these layers and transport them down the river. There, arsen can react with organic matter that is commonly dumped into the river in heavily populated areas without proper waste water treatment to form arsenic. These arsenite containing waters can sink all the way into the ground water. Arsenite is a big problem because it is a non-biodegradable toxin which can cause cancer and other serious diseases as it accumulates in our bodies.

To address this problem, one needs to have means to measure the presence of arsenite. Using mass-spectrometry, it is possible to measure the amounts of arsenite in water samples. However, these technical solutions are very expensive because the equipment is expensive, and extremely sensitive requiring more money to maintain. Poor countries may not be able to afford these solutions. This is where Hauke Harms research comes in.

His research group was able to reprogram E. coli bacteria to emit a blue luminescent light when arsenite is present. They did so by inserting the gene to produce this luminescent light into the same operon (same set of instructions) that becomes active when arsenic is pumped out of E. coli cells as these bacteria do not like arsenic either. Instead of an expensive mass-spectrometer, one now only needs a cheap apparatus with a light sensor to detect the faint blue light. The researchers envisage that these bacteria could be placed onto paper strip tests similar to the way we measure blood sugar. After a certain period of time of exposing the strip to the water sample, the paper strip could be read by the much cheaper light sensor.

On a personal note, I think that applications from these sorts of bio-sensors are remarkable and exciting as their fields of application are wide-ranging extending all the way to the medical field.

For his research, Professor Hauke Harms recently received the "Erwin Schrödinger" Award for 2010.

Literature Cited:

An early paper on this topic from his research group can be found here:

Judith Stocker, Denisa Balluch, Monika Gsell, Hauke Harms, Jessika Feliciano, Sylvia Daunert, Khurseed A. Malik, and Jan Roelof van der Meer. "Development of a Set of Simple Bacterial Biosensors for Quantitative and Rapid Measurements of Arsenite and Arsenate in Potable Water."
Environ. Sci. Technol., 2003, 37 (20), pp 4743–4750

The recent news were based on recent publication that further optimized storage and preservation of these bacteria:

Kuppardt A, Chatzinotas A, Breuer U, van der Meer JR, Harms H. "Optimization of preservation conditions of As (III) bioreporter bacteria."
Appl Microbiol Biotechnol. 2009 Mar;82(4):785-92. Epub 2009 Feb 6.

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