"Forming a biofilm is one of the crucial steps in cholera's progression," said Bassler, the Squibb Professor in Molecular Biology and head of the research group. "They cover themselves in a sort of goop that's a shield against antibiotics, allowing them to grow rapidly. When they sense there are enough of them, they try to leave the body."
Cholera bacteria use the human intestines as a breeding ground, and after enough cholera bacteria have grown there, they seek to escape and find other creatures to infect. They detach themselves from the intestines and benefit from the accumulation of toxins they release into the body. These toxins irritate the body, and it attempts to flush the bacteria out with vomiting and diarrhea. So violent is the effect that if the body is not quickly rehydrated, a victim can die within a day.
Bassler's team realized that the cholera must be signaling each other with some unknown chemical when the time was right to stop reproducing and exit the body. But no one before had found it.
"We generically understood that bacteria talk to each other with quorum sensing, but we didn't know the specific chemical words that cholera uses," Bassler said. "Doug (Higgins) led the hard work that was necessary to figure that out."
Higgins isolated the CAI-1 chemical, which occurs naturally in cholera. Then, Megan Pomianek, a graduate student in the laboratory of Martin Semmelhack, a professor of chemistry at Princeton, determined how to make the molecule in the laboratory. Higgins used this chemical essentially to control cholera's behavior in lab t
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