QLD: Qld researchers find culprit gene in vomit-causing bacteria

AAP General News (Australia)
04-08-2004
QLD: Qld researchers find culprit gene in vomit-causing bacteria

By Lloyd Jones

CAIRNS, Qld, April 8 AAP - Australian scientists have found a gene responsible for
creating a vomit-inducing toxin that poisons millions of rice eaters around the world
each year.

James Cook University (JCU) microbiologists in Townsville discovered the gene in the
bacteria Bacillus cereus which uses rice starch to make the toxin that causes the widespread
food poisoning.

The researchers also found the bacteria is only one genetic step from anthrax.

Their Bacillus cereus gene breakthrough could lead to tests that enable rice companies
to identify contaminated rice before it goes to market.

Research suggests up to one-fifth of all food poisoning outbreaks worldwide may be
caused by Bacillus cereus.

But the Townsville scientists warn cooking methods also play a part, such as when flash-fried
rice is left to cool down after reheating.

JCU postgraduate student Paul Horwood identified the gene in Bacillus cereus that enables
it to make the toxin cereulide in rice starch.

It is responsible for two food poisoning syndromes, one causing diarrhoea and the other,
commonly associated with rice and called emetic syndrome, causing acute nausea and vomiting.

Dr Graham Burgess, who co-supervised Mr Horwood's study, said there were few documented
Australian cases but a mass food poisoning at a Melbourne mosque in 2002 implicated Bacillus
cereus in rice.

"In certain restaurants in Australia you'd expect this could be a real problem, especially
poorly managed restaurants.

"We're yet to do a really good survey in Australia but we think if we did, we would
find this much more common than a lot of people think."

Dr Burgess said classic cases involved pre-cooked rice delivered warm to schools in Japan.

Mr Horwood said in some restaurants rice was flash-fried, left to cool down then flash-fried
again to make it warm. Sometimes it was stored overnight to use the next day.

But the spores of the organism could germinate in stored food and produce large amounts
of toxin that would not be destroyed by subsequent cooking.

"Within 30 minutes to two hours of eating the contaminated rice, you start vomiting
and this lasts for around 24 hours," Mr Horwood said.

Dr Burgess said the molecular method used in the JCU project to detect the genes should
assist in developing stronger quality controls for the rice industry.

The JCU research also established that Bacillus cereus had similar genes to Bacillus
anthracis, which causes anthrax, with the only difference being extra loops of DNA.

The study results had been passed on to Queensland's Department of Health, Dr Burgess said.

The project was funded by the Rural Industries Research and Development Corporation
and the Ricegrowers Cooperative.

AAP ldj/sc/dl/br a

KEYWORD: RICE

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