Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2018
Publication Date: 7/10/2018
Citation: Okrent, R.A., Trippe, K.M., Manning, V., Walsh, C. 2018. Detection of 4-formylaminooxyvinylglycine in Pseudomonas fluorescens WH6 and Pantoea ananatis BRT175 by laser absorption electrospray ionization-mass spectrometry. PLoS One. 13(7):e0200481. https://doi.org/10.1371/journal.pone.0200481.
Interpretive Summary: Soil microbes produce a vast number of biological compounds known as secondary metabolites, that mediate interactions with plants, insects, nematodes, and other microbes. Some of these chemicals are quite potent, and have the capacity to suppress the development of plant diseases and/or suppress the germination of weeds. Therefore, it is of tremendous interest to detect, purify, and describe these compounds so that they can be developed into technologies that address agricultural challenges. Because isolating water-soluable compounds is difficult and requires complex extraction and purification methods, the techniques used to purify microbial metabolites have preferentially focused on compounds that are not miscible in water. Because water soluble compounds have generally been overlooked, there is vast potential to discover new compounds that may be useful. In the current study, we evaluate the use of laser absorption electrospray ionization-mass spectrometry (LAESI-MS) to determine if it is useful to detect formylaminooxyvinylglycine (FVG), a potent and biologically useful compound that is extremely soluble in water, and therefore difficult to detect by other analytical methods. Here, we validate that LAESI-MS detects FVG with minimal sample preparation in bacteria known to produce FVG. We then demonstrate the usefulness of this LAESI-MS by describing the ability of a different bacterium to produce FVG. This research will allow scientists to screen large numbers of bacteria for their enhanced ability to produce FVG and may facilitate the discovery and detection of other related compounds.
Technical Abstract: 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, neither technique is amendable for high throughput analysis. Here, we report the development of a new technique that detects FVG in culture filtrates using laser absorption electrospray ionization-mass spectrometry (LAESI-MS). Unlike other methods, this technique allows for the rapid and robust analysis of crude culture filtrates. Using LAESI-MS, FVG was found to be produced by the bacterium Pantoea ananatis BRT175, the first example of FVG production by a non-pseudomonad.