Study reveals how pathogenic bacteria survive

University of Maryland researchers have discovered how pathogenic bacteria survive in animals and humans, a finding that could produce new ways to fight infections, according to a study in the Proceedings of the National Academy of Sciences (May 14, 2012).

Researchers from the University of Maryland School of Dentistry demonstrated how gram-negative bacteria regulate themselves to adapt to temperature changes, according to a school press release.

The research group, led by Yanyan Li, PhD, studied the changes that occur on the surface of bacteria when the organism adapts to growth at different temperatures.

All bacteria must adapt to survive when they enter a host, they noted. Alterations in the structure of the outer membrane surface of bacteria -- known as lipopolysaccharides (LPSs) -- is a singular mechanism that is responsible for this surface adaptation, the study authors noted.

LPSs are large molecules found in the outer membrane of gram-negative bacteria that act as endotoxins and elicit strong immune responses.

To study bacterial adaptation, the researchers manipulated the temperature and analyzed how the bacterial surface changed. This analysis showed that at different temperatures, specific LPS structures were present in the outer membrane. They also identified that this adaptation required a second LPS enzyme acquired from a different species of bacteria.

The research team then mutated each of these bacterial enzymes, which prevented the bacteria from being able to adapt to warm-blooded human temperatures.

The altered bacterial strain was avirulent and, in fact, from a subsequent lethal challenge, the study authors reported. These findings could be used to generate a live vaccine strain or identify bacterial components that could be the basis for future vaccines, they concluded.