Bacterial attraction and quorum sensing inhibition in Caenorhabditis elegans exudates.
Caenorhabditis elegans, a bacterivorous nematode, lives in complex rotting fruit, soil, and compost environments, and chemical interactions are required for mating, monitoring population density, recognition of food, avoidance of pathogenic microbes, and other essential ecological functions. Despite being one of the best-studied model organisms in biology, relatively little is known about the signals that C. elegans uses to interact chemically with its environment or as defense. C. elegans exudates were analyzed by using several analytical methods and found to contain 36 common metabolites that include organic acids, amino acids, and sugars, all in relatively high abundance. Furthermore, the concentrations of amino acids in the exudates were dependent on developmental stage. The C. elegans exudates were tested for bacterial chemotaxis using Pseudomonas putida (KT2440), a plant growth promoting rhizobacterium, Pseudomonas aeruginosa (PAO1), a soil bacterium pathogenic to C. elegans, and Escherichia coli (OP50), a non-motile bacterium tested as a control. The C. elegans exudates attracted the two Pseudomonas species, but had no detectable antibacterial activity against P. aeruginosa. To our surprise, the exudates of young adult and adult life stages of C. elegans exudates inhibited quorum sensing in the reporter system based on the LuxR bacterial quorum sensing (QS) system, which regulates bacterial virulence and other factors in Vibrio fischeri. We were able to fractionate the QS inhibition and bacterial chemotaxis activities, thus demonstrating that these activities are chemically distinct. Our results demonstrate that C. elegans can attract its bacterial food and has the potential of partially regulating the virulence of bacterial pathogens by inhibiting specific QS systems.
Kaplan
Fatma
F
Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville, FL, USA.
Badri
Dayakar V
DV
Zachariah
Cherian
C
Ajredini
Ramadan
R
Sandoval
Francisco J
FJ
Roje
Sanja
S
Levine
Lanfang H
LH
Zhang
Fengli
F
Robinette
Steven L
SL
Alborn
Hans T
HT
Zhao
Wei
W
Stadler
Michael
M
Nimalendran
Rathika
R
Dossey
Aaron T
AT
Brüschweiler
Rafael
R
Vivanco
Jorge M
JM
Edison
Arthur S
AS
D000818:Animals; D017173:Caenorhabditis elegans / Q000382:microbiology / Q000502:physiology*; D002633:Chemotaxis / Q000187:drug effects; D005122:Exudates and Transudates / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D011550:Pseudomonas aeruginosa / Q000254:growth & development; D016958:Pseudomonas putida / Q000254:growth & development; D053038:Quorum Sensing / Q000187:drug effects*; D012097:Repressor Proteins / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism
D012097:Repressor Proteins; D015534:Trans-Activators; C064778:LuxR autoinducer binding proteins