Scientists sequence largest bacterium genome so far

LONDON (Reuters) -- Scientists in the United States said Wednesday they had mapped the genome of a bacterium that is deadly for cystic fibrosis sufferers and that this could lead to the development of new antibiotics.

Researchers at the University of Washington and the Seattle-based biotechnology company PathoGenesis Corp have sequenced the 5,500 genes of Pseudomonas aeruginosa, the largest bacterium that has been mapped so far.

It is the major cause of death of cystic fibrosis sufferers and causes infection in burn victims and AIDS and cancer patients.

The sequencing of all the genes in the bacterium will allow scientists to discover how it lives in different environments and manages to elude the immune system and resist antibiotics.

"There is a lot we don't know about how the bacterium grows in diverse environments and how it protects itself. The genome sequence is the first step in trying to understand that question and how to deal with pathogens that have this kind of versatility," Maynard Olson, the University of Washington scientist who led the research team, said in a telephone interview.

The bacterium is intriguing for scientists because unlike other bacteria it is very adaptable, lives in drainpipes, showers and soil and cannot be destroyed with common disinfectants.

Knowing its genetic makeup will help scientists develop new drugs to destroy it and improve their understanding of what happens when it enters the body.

"We have identified functions of P. aeruginosa that were previously unknown, suggesting new avenues for drugs to treat serious lung infections caused by this bacterium," C. Kendall Stover, of PathoGenesis, said in a statement.

"We have new ideas on how to identify antibiotics that might circumvent some of the bacterium's intrinsic drug resistance mechanisms."

The bacterium is so resistant to antibiotics because it can detoxify itself. When it recognizes a foreign chemical in the cell it uses a so-called pump to expel it.

"An obvious path forward is to take these pumps that have been recognized in genome sequencing and try to develop drugs that target them," Olson added.

The Cystic Fibrosis Foundation in the United States, which funded the research along with PathoGenesis, believes the sequencing of the bacterium -- reported in the science journal Nature -- will improve the lives of patients with the genetic disease that occurs in about one in every 2,000 births.

The illness causes the body to produce thick mucus that obstructs the lungs, pancreas and digestive tract. Two decades ago only 12 percent of children with the disease survived beyond adolescence but an increasing number of sufferers are living into their 40s.

"This map of the genome provides scientists with a powerful tool that opens up new doors to developing innovative therapies that will make a difference to many lives," said Robert Beall, president of the Cystic Fibrosis Foundation in the United States.

So far scientists have mapped the genomes of 25 bacteria but P. aeruginosa is the largest and most complicated.

"A genome sequence provides a way of organizing the known information about an organism and relating what you are doing to other relevant work in the same organism or even other organisms that are quite different," Olson added.

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Cystic Fibrosis Foundation
Cystic Fibrosis Research, Inc. (CFRI)
PathoGenesis Corporation

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