The current environmental problems require the use of low-energy, environmentally friendly methods and nature-like technologies for the creation of materials. In this work, we aim to study the possibility of the direct biotransformation of fibrillar cellulose by fungi through obtaining a cellulose/mycelium-based biocomposite. The cellulose micro- and nanofibrils were used as the main carbon sources in the solid-phase cultivation of basidiomycete Trametes hirsuta. The cellulose fibrils in this process act as a template for growing mycelium with the formation of well-developed net structure. The biotransformation dynamics of cellulose fibrils were studied with the help of scanning electron microscopy. The appearance of nitrogen in the structure of formed fibers was revealed by elemental analysis and FTIR-spectroscopy. The fibers diameters were estimated based on micrograph analysis and the laser diffraction method. It was shown that the diameter of cellulose fibrils can be tuned by fungi through obtaining cellulose-based mycelium fibers with a narrower diameter-size distribution as compared to the pristine cellulose fibrils. The morphology of the resulting mycelium differed when the micro or nanofibrils were used as a substrate.

Sixty-six isolates of basidiomycete fungi were screened for the ability to synthesize cellulase. The effect of temperature on cellulase activity was studied for eight basidiomycete strains as perspective producers of ethanol. The temperature optima of enzyme activity ranged between 26 and 32°C. Direct conversion of Na-carboxymethyl cellulose, microcrystalline cellulose and rye straw were studied for seven basidiomycetes strains: Fomitopsis pinicola MT-5.09, F. pinicola MT-5.21, Piptoporus betulinus MT-30.04, Fomes fomentarius MT-4.05, F. fomentarius MT-4.23, Trametes hirsuta MT-24.24, Flammulina velutipes MT-3.03 Maximum ethanol production from Na-carboxymethyl cellulose (1.3 g/dm³) was achieved by strain F. velutipes MT-3.03. Strain F. fomentarius MT-4.05 more effectively converted rye straw to ethanol with yield of 1.1 g/dm³.

: Despite their efficiency, existing methods to dispose of drilling fluids used in the construction of oil and gas wells (chemical treatment of spent solutions, thermal method, thickening) are often expensive and unsustainable. Basidiomycota are natural xylotroph destructors that process lignocellulosic substrate – one of the most stable biopolymers in nature. Prospects for using enzyme preparations based on Basidiomycota as biodestructors of organic substances are evident due to the high efficiency and zero-waste production. The aim was to obtain an enzyme preparation based on the Trametes hirsute MT-17.24 Basidiomycota strain and evaluate its ability to biodegrade polyanionic cellulose, used as a viscosifier for drilling fluids in the construction and repair of oil and gas wells. Screening of cellulase activity of the following strains was carried out: Fomitopsis pinicola MT-5.21, Fomes fomentarius MT-4.05, Lactarius necator, Schizophyllum commune MT-33.01, Trametes versicolor It-1, Trametes hirsute MT-17.24, Trametes hirsuta MT-24.24. To obtain the enzyme preparation, the T. hirsuta MT-17.24 strain was selected, which demonstrated the highest coefficient of cellulase activity (10.9). A medium for solid-phase cultivation of this strain was selected. Enzymatic activity of the enzyme preparation was studied on a model drilling fluid. A 10-hour experiment showed that the use of a 1% enzyme preparation leads to a decrease in the plastic viscosity of the drilling fluid from 16 to 8 mPa·s. The research results demonstrate the efficiency of enzyme preparations based on Basidiomycota in the biodestruction of polyanionic cellulose.