Detection of 4-formylaminooxyvinylglycine in culture filtrates of Pseudomonas fluorescens WH6 and Pantoea ananatis BRT175 by laser ablation electrospray ionization-mass spectrometry

The oxyvinylglycine 4-formylaminooxyvinylglycine (FVG) arrests the germination of weedy grasses and inhibits the growth of the bacterial plant pathogen Erwinia amylovora. Both biological and analytical methods have previously been used to detect the presence of FVG in crude and extracted culture filtrates of several Pseudomonas fluorescens strains. Although a combination of these techniques is adequate to detect FVG, none is amenable to high-throughput analysis. Likewise, filtrates often contain complex metabolite mixtures that prevent the detection of FVG using established chromatographic techniques. Here, we report the development of a new method that directly detects FVG in crude filtrates using laser ablation electrospray ionization-mass spectrometry (LAESI-MS). This approach overcomes limitations with our existing methodology and allows for the rapid analysis of complex crude culture filtrates. To validate the utility of the LAESI-MS method, we examined crude filtrates from Pantoea ananatis BRT175 and found that this strain also produces FVG. These findings are consistent with the antimicrobial activity of P. ananatis BRT175 and indicate that the spectrum of bacteria that produce FVG stretches beyond rhizosphere-associated Pseudomonas fluorescens.