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Bacteria programmed to respond to dangerous a -

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Lara Bereza-Malcolm: Bacteria have a pretty bad reputation. They are continually linked to outbreaks of disease, sickness and death, with misinformation fuelling a terrifying paranoia of our microscopic friends. We tend to forget how fantastic and useful they are to us. The majority of bacteria are not harmful to humans and are responsible for sustaining all life on Earth through environmental processes such as the carbon and nitrogen cycles, along with the removal of toxic compounds from the soil.

Microbes are found almost everywhere on the planet, including the most extreme environments, from underwater volcanoes to the Antarctic ice floes. The scientific community is recognising how excellent microbes are as biological sensors. They are able to rapidly detect change in their environment, including fluctuations in temperature, toxins, and react to stimuli they detect through programmed genetic responses.

My name is Lara Bereza-Malcolm, and I am interested in using bacteria as sniffer dogs to warn us to the presence of dangerous and toxic compounds in the environment. I plan to tap into their genetic responses and reprogram them for our benefit. My research involves novel microbial-based biosensors. Positive detection of the target will then result in a signal being emitted which we can detect and potentially measure the amount of that chemical present. Microbial based biosensors do the detecting work for us and can be easily incorporated into a testing kit for the detection of specific compounds in their environment.

To take advantage of bacteria sniffer dogs I will be using synthetic biology, a revolutionary new field that is reinventing molecular cloning. This is a new area of research that combines the molecular techniques of biology and the design processes of engineering to create new biological systems based off naturally occurring processes.

Traditionally, scientists have been limited to the discovery of processes which have evolved in nature. Synthetic biologists employ a different approach. This pre-existing treasure trove of genetic information can be used to create new biological pathways to perform specific tasks. Ready-to-assemble DNA sequences with specific functions are available in modules known as bio-bricks. These bio-bricks are interchangeable, allowing us to build higher level function pathways. Think of how a child would use Lego bricks to build a larger structure from smaller parts. This results in the construction of microbes with specialised beneficial functions.

I am assembling multiple DNA sequences of known functions in different ways to construct new signalling and sensing pathways. My initial microbial biosensors will be designed based on the detection of arsenic, cadmium, lead and mercury, all contaminants are that are harmful to human health and our ecosystem.

I am currently designing these biological systems to elicit a visible fluorescent response to these heavy metals. When the target is not present, the microbes will glow red. When they detect a harmful compound they will glow green. We can take this further by designing a multiplex signalling system which will detect multiple compounds at once. With each different input detected we may receive a different coloured fluorescence. Noting the colour of bacteria will let us know if there is arsenic, cadmium or mercury in the local water or soil.

I will also move these biological systems into different species of bacteria to increase the range of environments we can detect, such as the soil subsurface or at the bottom of the ocean. There are many benefits to programming bacteria just as we would a computer. We can further program bacteria to respond to dangerous chemicals to remove these harmful compounds. This rapid detection and response is essential if we want to successfully stop the introduction of harmful chemicals into the food chain.

I believe that synthetic biology technology and the development of microbial biosensors will result in cheaper, more efficient green technology to benefit everyone.

Robyn Williams: Lara Bereza-Malcolm at La Trobe University in Melbourne, doing her PhD with DNA Lego.