Wednesday, January 27, 1999 Published at 19:14 GMT
'Superbugs' possible from genetically modified food
Some maize fed to cattle contains antibiotic resistance genes
Fears that genetically-modified foods might promote drug-resistant "superbugs" have been fuelled by new research.
Dutch scientists used a computer-controlled artificial gut to show that DNA remains intact for several minutes in the large intestine.
Hub Noteborn, of the State Institute for Quality Control of Agricultural Products in Wageningen, said in New Scientist magazine: "It was a surprise to see that DNA persisted so long in the colon."
If the transferred genes were the antibiotic-resistance genes used as markers in some GM crops fed to livestock, then serious health risks might result. The danger would be that antibiotic-resistant microbes would spread from animals to humans.
The experiments used bacteria genetically modified to contain antibiotic-resistant genes. As these were digested in the artificial gut, half the DNA survived for six minutes.
"This makes it available to transform cells," said Robert Havenaar, of the TNO Nutrition and Food Research Institute in Zeist. His team designed the artificial gut which provides a mechanical model of the stomach and intestines and contains the normal microbes and enzymes.
However, the Flavr Savr tomato, engineered by Calgene to resist rot, did not pass on antibiotic resistant genes, although up to 10% of its DNA reached the colon.
The crucial test will be whether GM foods and bacteria which have infected the gut can transfer genes. Havenaar says he will ask the European Union to fund further research.
The new findings show more research is essential, says Derek Burke, former chair of Britain's Advisory Committee on Novel Foods and Processes. "We can only say that the risk is not zero," he says. "Anything that would help put numbers on this, would be useful."
A UK House of Lords select committee recently said that the potential benefits from genetically modified crops far outweigh the risks. However, they still recommended that the use of antibiotic-resistance genes in crops such as the maize fed to some US cattle should be "phased out as quickly as possible".