Several scientists around the city have collected DNA samples from several forms of bacteria commonly found in food, the first step in developing a chip that can test food samples in a matter of hours.

The city has invested two million yuan (US$250,000) in the project since it was launched in 2006 in order to improve food-hygiene levels in the city, an issue that has grown in importance with reports of several mass food poisoning cases.

"We want to find a quick and dependable way to detect the safety of the food we eat everyday," said Zhao Yong, a researcher at Shanghai Fisheries University who is in charge of the project.

Researchers attach DNA samples from common bacteria to a small piece of glass that is covered in a fluorescent substance that reacts if the food samples tested contains the same bacteria.

A chip containing numerous bacteria samples could test a food sample in less than three hours, Zhao said. Similar tests now take up to a week as the bacteria has to be allowed to grow before scientists can spot it.

To date, Zhao has found and cloned more than 150 DNA sections from six major forms of bacteria found in food, such as salmonella.

He continues to study and collect DNA samples from other bacterias to make the chip work more precisely.

"It's like a battery: when its two electrodes connect to a bulb, it lights up," said Zhao, noting that the new chip can also detect different kind of bacteria.

He said the chip will be ready for use by 2008 and the city's food safety inspection authorities should be using it by 2009.

Food poisoning has become a crucial social issue in the city. Last September, more than 200 people in Pudong ingested clenbuterol, an illegal chemical used to feed pigs.

Last August, more than 50 people in Beijing were poisoned after eating a kind of spiral shell - a popular food served in Chinese restaurants.

(Source: www.shanghai.gov.cn )