Molecular characterization of ombrotrophic peats by humeomics

Abstract

Abstract Background An insight into the molecular composition of ombrotrophic peats of different geographical origin and collected at different depths was achieved by the humeomics method. The humeomic fractionation allowed the separation of molecular components in either organic solvents or water on the basis of their progressive binding strength to the humic matrix. The solubilized matter in fractions was analyzed by gas chromatography–mass spectrometry (GC–MS) or by proton nuclear magnetic resonance (1H NMR) spectroscopy, while the residues depleted of the extracted material were observed by 13C cross-polarization magic-angle-spinning nuclear magnetic resonance (13C-CPMAS-NMR) spectroscopy. Results The analytical characterization of fractions and residues differentiated peats not only on the basis of the different classes of extracted molecules, but also on their binding strength to the complex peat matrix. Aromatic, lipidic, and sugar compounds were the most representative molecular classes extracted in the humeomic fractions and their abundance varied with depth. The distribution and abundance of extracted compounds provided an indication of the extent of organic matter accumulation in peat. The NMR spectra of solid residues supported the interpretation of the characteristics of the various extracts. Conclusions Our findings proved that the humeomic approach allows to provide important information on both the molecular composition of peats and its variation with depth.

Keywords

• Peat
• Humus
• Organic matter
• Humeomics
• Fractionation
• GC–MS