SdiA, an N-acylhomoserine lactone receptor, becomes active during the transit of Salmonella enterica through the gastrointestinal tract of turtles.
BACKGROUND
LuxR-type transcription factors are typically used by bacteria to determine the population density of their own species by detecting N-acylhomoserine lactones (AHLs). However, while Escherichia and Salmonella encode a LuxR-type AHL receptor, SdiA, they cannot synthesize AHLs. In vitro, it is known that SdiA can detect AHLs produced by other bacterial species.


RESULTS
In this report, we tested the hypothesis that SdiA detects the AHL-production of other bacterial species within the animal host. SdiA did not detect AHLs during the transit of Salmonella through the gastrointestinal tract of a guinea pig, a rabbit, a cow, 5 mice, 6 pigs, or 12 chickens. However, SdiA was activated during the transit of Salmonella through turtles. All turtles examined were colonized by the AHL-producing species Aeromonas hydrophila.


CONCLUSIONS
We conclude that the normal gastrointestinal microbiota of most animal species do not produce AHLs of the correct type, in an appropriate location, or in sufficient quantities to activate SdiA. However, the results obtained with turtles represent the first demonstration of SdiA activity in animals.
Smith
Jenee N
JN
Department of Microbiology, The Ohio State University, Columbus, Ohio, United States of America.
Dyszel
Jessica L
JL
Soares
Jitesh A
JA
Ellermeier
Craig D
CD
Altier
Craig
C
Lawhon
Sara D
SD
Adams
L Garry
LG
Konjufca
Vjollca
V
Curtiss
Roy
R
Slauch
James M
JM
Ahmer
Brian M M
BM
D000333:Aeromonas / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D002417:Cattle; D002645:Chickens; D005260:Female; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006168:Guinea Pigs; D007783:Lactones / Q000737:chemistry; D051379:Mice; D008808:Mice, Inbred CBA; D008954:Models, Biological; D011817:Rabbits; D019779:Salmonella enterica / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D014426:Turtles / Q000382:microbiology
D001426:Bacterial Proteins; D007783:Lactones; C097686:SdiA protein, bacteria; D015534:Trans-Activators