Innovative chitin-glucan based material obtained from mycelium of wood decay fungal strains.

Fungi are an alternative source to animal-based chitin. In fungi, chitin fibrils are strongly interconnected and bound with glucans that justify the unique matrix. The present study aimed to extract chitin and glucans from the mycelium of several wood decay fungal strains in order to obtain flexible materials and to check correlations between chitin content and the mechanical properties of these materials. Five strains were chosen in consideration of their different cell wall chemical composition (high content of α-glucans, ß-glucans or chitin) to evaluate how these differences could influence the mechanical and chemical characteristics of the material. The fungal strains were cultivated in liquid-submerged dynamic fermentation (both flasks and bioreactor). Chitin and glucans were crosslinked with acetic acid and plasticized with glycerol to obtain flexible sheets. Abortiporus biennis, Fomitopsis iberica and Stereum hirsutum strains were found to adapt to produce material with adequate flexibility. The obtained materials were characterized by Thermogravimetric analysis (TGA) for the understanding of the material composition. The material obtained from each species was mechanically tested in terms of tear strength, elongation at break, and Young's modulus.

NMR-Based Characterization of Wood Decay Fungi as Promising Novel Foods: Abortiporus biennis, Fomitopsis iberica and Stereum hirsutum Mycelia as Case Studies.

Wood Decay Fungi (WDF) are fungi specialized in degrading wood. An interesting perspective is their use as a source of Novel Foods or food ingredients. Here, for the first time, the metabolite profiling of hydroalcoholic and organic extracts from A. biennis, F. iberica, S. hirsutum mycelia was investigated by NMR methodology. Amino acids (alanine, arginine, asparagine, aspartate, betaine, GABA, glutamate, glutamine, histidine, isoleucine, leucine, lysine, phenylalanine, threonine, tryptophan, tyrosine, valine), sugars (galactose, glucose, maltose, trehalose, mannitol), organic acids (acetate, citrate, formate, fumarate, lactate, malate, succinate), adenosine, choline, uracil and uridine were identified and quantified in the hydroalcoholic extracts, whereas the 1H spectra of organic extracts showed the presence of saturated, mono-unsaturated and di-unsaturated fatty chains, ergosterol,1,2-diacyl-sn-glycero-3-phosphatidylethanolamine, and 1,2-diacyl-sasglycero-3-phosphatidylcholine. A. biennis extracts showed the highest amino acid concentration. Some compounds were detected only in specific species: betaine and mannitol in S. hirsutum, maltose in A. biennis, galactose in F. iberica, GABA in F. iberica and S. hirsutum, and acetate in A. biennis and S. hirsutum. S. hirsutum showed the highest saturated fatty chain concentration, whereas DUFA reached the highest concentration in A. biennis. A high amount of ergosterol was measured both in A. biennis and F. iberica. The reported results can be useful in the development of WDF-based products with a high nutritional and nutraceutical value.

Collection and Characterization of Wood Decay Fungal Strains for Developing Pure Mycelium Mats.

Wood decay fungi (WDF) seem to be particularly suitable for developing myco-materials due to their mycelial texture, ease of cultivation, and lack of sporification. This study focused on a collection of WDF strains that were later used to develop mycelium mats of leather-like materials. Twenty-one WDF strains were chosen based on the color, homogeneity, and consistency of the mycelia. The growth rate of each strain was measured. To improve the consistency and thickness of the mats, an exclusive method (newly patented) was developed. The obtained materials and the corresponding pure mycelia grown in liquid culture were analyzed by both thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) to evaluate the principal components and texture. TGA provided a semi-quantitative indication on the mycelia and mat composition, but it was hardly able to discriminate differences in the production process (liquid culture versus patented method). SEM provided keen insight on the mycelial microstructure as well as that of the mat without considering the composition; however, it was able to determine the hyphae and porosity dimensions. Although not exhaustive, TGA and SEM are complementary methods that can be used to characterize fungal strains based on their desirable features for various applications in bio-based materials. Taking all of the results into account, the Fomitopsis iberica strain seems to be the most suitable for the development of leather-like materials.