Decomposition of lignin in wheat straw in a sand-dune grassland

The degradation of organic macromolecules, including lignin, in plant-derived soil organic matter, is important to the global carbon cycle. In grasslands, saprotrophic (decomposer) fungi are major decomposers of such organic material. The aim of this study was to characterise lignin degradation, particularly with respect to lignin oxidation typical of white-rot basidiomycete fungi. Lignin breakdown products, analysed by gas chromatography–mass spectrometry (GC–MS) with TMAH thermochemolysis, in initial wheat (Triticum aestivum var. Swatham) straw samples were compared with those in samples which had been buried as a “model” resource for 46 months in a sand-dune grassland at Ainsdale National Nature Reserve, Lancashire, UK. Our results showed that lignin oxidation occurred in the straw over the 46 month period, as there were general increases in the [Ac/Al]S and [Ac/Al]G ratios and a clear decrease in the [S/G] ratio. These data provide tentative support for the theory that white-rot basidiomycete fungi are involved in the degradation of lignin in grasslands. ► Lignin degradation determined in wheat straw after 46 months burial in sandy grassland. ► Lignin oxidation indicative of white-rot basidiomycetes was found. ► [Ac/Al]S and [Ac/Al]G ratios increased and [S/G] ratio decreased