about this research in Agricultural Research.
Salmonella Uses Chemical to Communicate
By Sharon Durham
January 27, 2000
Chemical communication between
animals, particularly insects, has been well documented through scientific
study. Now, add microorganisms to the list of creatures that communicate this
way. An Agricultural Research Service
scientist has found that Salmonella bacteria release a chemical that
directly affects the growth of these organisms.
Veterinarian Jean Guard-Petter, who is in ARS
Southeast Poultry Research Unit at
Athens, Ga., found that the food pathogen Salmonella enteritidis uses
the chemical acyl-homoserine lactone, or AHL, as a communication tool. Each
Salmonella bacteria puts out a low level of AHL, but when the population
grows, so does the amount of AHL. At high levels, AHL prompts Salmonella
to grow beyond its original genetic programming and signals cells to produce
molecules that increase virulence. The abundance of these organisms in a
confined space, such as the spleen of the chicken, forces them to move to
another area, sometimes a hens eggs.
Even though Salmonella contaminates a small fraction of the 45
billion eggs produced each year in the United States, this still translates
into a significant amount of illness. Occurrences of S. enteritidis food
poisoning have increased fourfold in the U.S. and 40-fold in Europe in the past
Petter was the first to see that AHL is a factor in S.
enteritidis rapid growth and spread. She made her discovery by using
a special plasmid reporter system that inserts genes in S. enteritidis
bacteria. These genes cause the bacteria to emit light if they are producing
AHL. As the light grows brighter, it indicates growth to a high cell density.
Dr. Petters discovery may provide another tool for improving food safety.
Read more about inter-bacterial communication research in the January issue
of Agricultural Research
ARS is the chief scientific agency in the U.S. Department of Agriculture.
Scientific contact: Jean Guard-Petter, ARS Southeast Poultry Research
Laboratory, 934 College Station Road, Athens, GA 30605; phone (706) 546-3446,
fax (706) 546-3161, firstname.lastname@example.org.