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Chemists Prevent Bacterial Conversations

pseudomonas aeruginosa



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Bad things happen when bacteria start talking, most of the time. Via a process known as quorum sensing, the microbes send out chemical signals that build up until they are notified that there are enough of them present to initiate an infection. They then begin acting as a team, exuding a biofilm over the colony that helps protect the members from antibiotics and ramps up their rate of growth. Chemists have begun to design compounds that can interfere with this conversation and, thanks to new techniques that allow more rapid compound detection, have isolated species-specific ones.

Helen Blackwell of the University of Wisconsin and her team have sped up the process of discovering such conversation stoppers by using microwaves to heat up--and therefore speed up--the chemical reactions that produce synthetic analogs of the bacteria's key signaling molecules. Creating the molecules more quickly also allows the researchers to test several possible analogs for effectiveness rather than just individual examples.

Using this accelerated method, Blackwell and her team have identified several such compounds that prevented detection of comrades among specific bacteria, such as Pseudomonas aeruginosa, which often plagues patients with health problems such as compromised immune systems. More important, it does not interfere with other bacteria's lines of communication, such as beneficial microbes in the human gut.

Blackwell also hopes to create compounds that can direct bacteria to do some of the good things they do, such as the nitrogen-fixing undertaken by soil microbes in root nodules or the bioluminescence of marine microorganisms. But such conversation stoppers--and their counterparts that facilitate communication--may find their first use as a prophylactic against nascent infections, allowing time for antibiotics to do their work. "We just keep bacteria from behaving badly," Blackwell says. She presented her research at the American Chemical Society meeting in San Francisco on September 10.

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