A biological sensor system built from an optical fiber at the end of which are fixed genetically engineered bacteria to produce light when they are exposed to chemicals that are harmful to their genetic material
Two weeks after September 11, Dr. Robert Marks, from the Faculty of Engineering at Be'er Sheva University, received a call from a respected institution in the USA, who asked to remain anonymous. The person he spoke with wanted to know if he could develop a kit to detect chemical warfare agents and bacteria used as biological weapons. "I answered him that, in my humble opinion, I could do so at least for some of these," says Marks.
Marks developed a biological sensor system built from an optical fiber with bacteria fixed at the end. The bacteria are genetically modified to produce light when they are exposed to chemicals that are harmful to their genetic material. The genetic engineering of the bacteria is carried out in the laboratory of Prof. Shimson Belkin from the Department of Environmental Microbiology at the Hebrew University. The system is very sensitive. Chemical toxins and bacterial toxins, heavy metals and pesticides in very small amounts (nanotoxins), which damage the DNA of the bacteria, cause the bacteria to glow. The fiber is inserted into a water sample, and the light is measured by a sensitive detector and transmitted directly to the computer. The intensity of the light produced by the bacteria indicates the concentration of the poison in the water.
Marks managed to reduce his system to the size of a box, which can be taken to the field and with which the test can be performed on the spot. The result is transferred to a laptop. "We took the system to the Sea of Galilee and checked the lake water for the presence of toxins that damage the genetic material of the bacteria. Such damage implies the sensitivity of our DNA to these substances. Fortunately, we did not find any injuries," says Marks. The existing test systems are indeed capable of detecting the presence of a chemical substance in a water sample with the help of sophisticated equipment, either by testing the toxicity to fish introduced into the lake or by means of bacteria, in a way similar to Marx's; However, in both cases the process is lengthy and requires the use of sophisticated laboratory equipment. "Our method is an independent system that does not require additional accessories," says Marks. The system was developed with the support of the Ministry of Science.
According to him, every water testing center in the world will be able to use its technology in a water reservoir, without the need to transfer the water to a central laboratory, as has been done so far. In this way, a technician will be able to test lake waters, transmit the results from his computer to a central laboratory, and continue to do tests in other places in the lake. Each test lasts between 60 and 90 minutes. When the central laboratory detects a high level of biological toxicity, the technician will be able to check the level of toxicity in the same place again during the day and perform additional tests if necessary.
Together with researchers from the Department of Biotechnology Engineering and the Institute for Applied Research in Life Sciences, Marks is now developing a biological system based on the luminescent bacteria, which will help protect the national water reservoirs from biochemical warfare.
Two years ago Marks, in collaboration with students Boris Polyak and Alex Novodborz, began to develop a method for detecting disease bacteria in water. "The discovery of bacteria is essentially different from the discovery of poisons, because you have to find a method to 'fish' the bacteria you want to test from the aquatic environment where they all are," says Marks. For this purpose, Marks attaches to the optical fiber antibodies against unique components of the bacterial wall, through which it is possible to characterize the particular bacteria. If there are bacteria in the water that you want to detect, they stick to their antibody, settle on the optical fiber, and activate an enzyme that causes the alert. In this way Marx was able to detect the presence of cholera bacteria in drinking water. Now he is working on developing such a system for detecting the botulinum bacterium. Marks hopes that the biological sensors he is developing will be able to serve as a central tool in detecting biological and chemical attacks in Israel and around the world.
