Cultivation of Fomitopsis betulina fruiting bodies on alternative substrates: Uncovering the metabolomics profiling by HR-MAS NMR and FTIR spectroscopies

Abstract

Fomitopsis betulina fruiting bodies, which are edible when young, were cultivated on four lignocellulosic substrates: birch (Betula alba, natural host, control), smoke tree (Cotinus coggygria), black alder (Alnus glutinosa), and hazelnut shells (Corylus avellana). To study the impact of substrate and developmental stage on chemical composition, samples were evaluated using FTIR spectroscopy to assess macromolecular features, HR-MAS ¹H NMR spectroscopy to profile low-molecular-weight metabolites, and multivariate statistical methods (PCA, SIMCA, OPLS-DA, and OPLS-HDA). Morphological classification was confirmed by chemometric analysis: young fruiting bodies were enriched in free sugars and β-glucan fragments, whereas mature specimens contained more chitin-derived oligomers, esters, and amide signals. These results demonstrate that substrate selection influences both amino acid and carbohydrate profiles, while maturation is associated with a shift from soluble sugars toward structural polysaccharides. From a practical perspective, harvesting at the early developmental stage favors the accumulation of free sugars and β-glucan fragments, whereas substrate selection can be optimized to enhance the nutritional, sensory, and technological properties of F. betulina.