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Published on: January 14, 2017
In-depth phospholipid profiling of plant-pathogenic bacteria after treatment with antimicrobial random peptide
Edward Rudt1, Christian Faist1, Vera Schwantes1
1Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße 48, D-48149, Münster, Germany.
Background:
The ability of plant-pathogenic bacteria to develop antimicrobial resistance against crop protection products represents a significant challenge. An alternative to conventional crop protecting products could be random peptide mixtures (RPMs), which potentially target the phospholipid-containing cell membrane. The randomized arrangement of the peptides minimizes the risk of bacterial resistance developing against the RPMs. However, not all plant-pathogenic bacteria exhibited growth inhibition after RPM treatment. Our prior studies revealed correlations between bacterial growth inhibition and changes in the fatty acid pattern following treatment. However, additional data on the intact phospholipid composition are essential to further understand and improve novel RPMs.
Results:
Accordingly, we developed an analytical setup for in-depth bacterial lipid membrane characterization based on two complementary methods in conjunction with chemometric data evaluation to study the impact of RPM treatment on phospholipid class and species level. An efficient phospholipid class quantitation using hydrophilic interaction liquid chromatography (HILIC)-based lipid class separation with uniform charged aerosol detection (CAD) revealed distinct differences in the class composition of six plant-pathogenic bacteria. Moreover, branched-chain fatty acid (BCFA)-comprising phospholipid profiling via liquid chromatography-tandem mass spectrometry (LC-MS/MS) provided additional lipid species information to classify the investigated bacteria based on the number of bound BCFA. The combination of these techniques served for a comprehensive characterization of the bacterial membrane adaptation to the RPM treatment, which showed some correlations with the inhibitory effects of the RPMs.
Significance:
In this proof-of-concept study, HILIC-CAD phospholipid quantitation and BCFA-comprising phospholipid profiling were introduced as complementary techniques for in-depth characterization of bacterial cell membranes as well as membrane adaptations at both phospholipid class and species level. Our developed analytical setup may facilitate future studies targeting in-depth characterization of bacterial lipid membranes.
