A scientist has developed a prize-winning DNA test allowing faster detection of the harmful E-coli bacteria than conventional methods. Dr Richard Kong Yuen-chong, assistant professor at the City University of Hong Kong's department of biology and chemistry, based his work on the polymerase chain reaction method to detect six pathogens in one test. The technique, which won a Nobel Prize for its developer, Dr Kary Mullis, involves amplifying a tiny amount of genetic material millions of times. Signature DNA, which is a tiny part of a bacteria's DNA, acts like a unique name-tag for every species of pathogenic bacteria and virus. Dr Kong found the signature DNA could indicate the presence of bacteria and viruses in water and food. After a year's investigation, he has developed a $100 test which in six hours can find six different species of pathogenic bacteria - three types of E-coli, two salmonella and one vibrio. Conventional tests detect one pathogenic bacterium, take two days and still cost $100. Dr Kong, whose work has been supported with a $2.2 million Industry Department grant, said he aimed to extend detection rates to 20 organisms in one test.