Identification of unsaturated N-acylhomoserine lactones in bacterial isolates of Rhodobacter sphaeroides by liquid chromatography coupled to electrospray ionization-hybrid linear ion trap-Fourier transform ion cyclotron resonance mass spectrometry.

摘要: The identification of two unsaturated N-acylhomoserine lactones (AHLs) produced by Rhodobacter sphaeroides bacteria, based on liquid chromatography (LC) coupled to a hybrid quadrupole linear ion trap (LTQ)-Fourier transform cyclotron resonance (FTICR) mass spectrometer upon electrospray ionization (ESI), is presented. Besides the confirmation signaling molecule already described in literature, i.e. (Z)-N-tetradec-7-enoyl-homoserine lactone (C14:1-HSL), we have discovered occurrence, at low, yet significant levels, another monounsaturated compound, C12:1-HSL, which may extend number small diffusible chemical signals known for R. sphaeroides. Both AHLs were identified high-resolution FTICR spectrometry extracts bacterial culture media and occurrence C=C bond was assessed their conversion into bromohydrins. Collision-induced dissociation (CID) spectra then collected LTQ analyzer. A careful comparison tandem MS (i.e., C12:1-HSL C14:1-HSL) saturated (i.e. C12-HSL C14-HSL) led emphasis series product ions, exhibiting 14 Da spaced m/z ratios. referred progressive fragmentations aliphatic end AHL acyl chains, followed neutral losses terminal alkenes CH2=CH(CH2)nH). In particular, located higher explored range (>200 Da), observed only species, enabled location between carbons 7 8 chain. Copyright © 2011 John Wiley & Sons, Ltd.