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Profiling acylated homoserine lactones in Yersinia ruckeri and influence of exogenous acyl homoserine lactones and known quorum‐sensing inhibitors on protease production
Author(s) -
Kastbjerg V. G.,
Nielsen K. F.,
Dalsgaard I.,
Rasch M.,
Bruhn J.B.,
Givskov M.,
Gram L.
Publication year - 2007
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2006.03109.x
Subject(s) - homoserine , quorum sensing , protease , lactone , microbiology and biotechnology , yersinia ruckeri , chemistry , biology , biochemistry , enzyme , virulence , gene , fishery , fish <actinopterygii> , rainbow trout
Aims: 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. Methods and 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°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. Significance and Impact of the Study: 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.