Profiling acylated homoserine lactones in Yersinia ruckeri and influence of exogenous acyl homoserine lactones and known quorum-sensing inhibitors on protease production.
OBJECTIVE
To profile the quorum-sensing (QS) signals in Yersinia ruckeri and to examine the possible regulatory link between QS signals and a typical QS-regulated virulence phenotype, a protease.


RESULTS
Liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) showed that Y. ruckeri produced at least eight different acylated homoserine lactones (AHLs) with N-(3-oxooctanoyl)-L-homoserine lactone (3-oxo-C8-HSL) being the dominant molecule. Also, some uncommon AHL, N-(3-oxoheptanoyl)-L-homoserine lactone (3-oxo-C7-HSL) and N-(3-oxononanoyl)-L-homoserine lactone (3-oxo-C9-HSL), were produced. 3-oxo-C8-HSL was detected in organs from fish infected with Y. ruckeri. Protease production was significantly lower at temperatures above 23 degrees C than below although growth was faster at the higher temperatures. Neither addition of sterile filtered high-density Y. ruckeri culture supernatant nor the addition of pure exogenous AHLs induced protease production. Furthermore, three QS inhibitors (QSIs), sulfur-containing AHL analogues, did not inhibit protease production in Y. ruckeri.


CONCLUSIONS
Exogenous AHL or sulfur-containing AHL analogues did not influence the protease production indicating that protease production may not be QS regulated in Y. ruckeri.


CONCLUSIONS
The array of different AHLs produced indicates that the QS system of Y. ruckeri is complex and could involve several regulatory systems. In this case, neither AHLs nor QSI would be likely to directly affect a QS-regulated phenotype.
Kastbjerg
V G
VG
Department of Seafood Research, Danish Institute for Fisheries Research, Lyngby, Denmark. vgk@difres.dk
Nielsen
K F
KF
Dalsgaard
I
I
Rasch
M
M
Bruhn
J B
JB
Givskov
M
M
Gram
L
L
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000032:analysis / Q000302:isolation & purification / Q000494:pharmacology; D000107:Acetylation; D000818:Animals; D001431:Bacteriological Techniques; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005663:Furans / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial; D013058:Mass Spectrometry / Q000379:methods; D017686:Oncorhynchus mykiss; D010447:Peptide Hydrolases / Q000032:analysis / Q000378:metabolism; D053038:Quorum Sensing / Q000187:drug effects; D015009:Yersinia Infections / Q000378:metabolism; D044124:Yersinia ruckeri / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism
D005663:Furans; C494198:furanone C-30; C088386:homoserine lactone; D010447:Peptide Hydrolases; D015107:4-Butyrolactone