Fast-growing poplar trees from plantations are the source of inexpensive wood that is intended mainly for chemical processing in the pulp and paper industry. Their potential as raw material for biofuel manufacturing is widely discussed as well. The detailed chemical composition of this raw material is therefore an important question. Five species of poplars were investigated: Populus alba, P. maximowiczii, P. trichocarpa, P. nigra, and P. tremula. Wood is a material consisting mainly of lignocellulose, but there are also many extractives. In temperate zone climate they typically represent up to 5% of wood mass. Their identification is difficult, due to various classes of compounds and great number of individual ones. These compounds can affect the properties of wood—its resistance to biotic agents and suitability to enzymatic treatment towards biofuels. Gas chromatography coupled with mass spectrometer (GC-MS) was used to analysis of extractives in various species of poplar wood. Compounds from several classes were identified like phenols, fatty acids, and their derivatives, sterols. Their identification was discussed along with estimation of their content in wood of investigated species.

The influence of bacterial cellulose gel film pretreatment methods on the efficiency of enzymatic hydrolysis was investigated. An increase in the efficiency of enzymatic hydrolysis due to liquid hot water pretreatment or steam explosion was shown. The glucose yield of 88% was obtained from raw, non-purified, bacterial cellulose treated at 130 °C. The results confirm the potential of bacterial cellulose gel film as a source for liquid biofuel production.

The crystalline structure of cellulose plays a crucial role in its reactivity, which is particularly important in biomass processing involving enzymatic hydrolysis. This study investigates the effect of low-frequency ultrasound (40 kHz) on the efficiency of enzymatic hydrolysis of cellulose in poplar wood and its structure, with a focus on its crystallinity and susceptibility to enzymatic hydrolysis. Two experimental pathways were explored: ultrasound-assisted hydrolysis of raw wood and isolated cellulose. Structural modifications were assessed using Fourier-transform infrared spectroscopy to determine the Lateral Order Index (LOI) and Total Crystallinity Index (TCI), providing insight into the reorganisation of cellulose microstructure. To evaluate hydrolysis efficiency, glucose yields were quantified by high-performance liquid chromatography. The application of ultrasound to raw wood resulted in minimal improvement in sugar release, whereas pretreatment of extracted cellulose led to a modest acceleration of enzymatic hydrolysis. The results show that ultrasound-assisted hydrolysis of raw wood did not significantly increase glucose yield, reaching only 9.9 ± 0.3% and 10.1 ± 0.8% for two poplar hybrids. Only slight increases in TCI and no significant changes in LOI were observed after 4 h of ultrasonic exposure. It indicates limited disruption of the crystalline structure under the tested conditions.

This paper presents the results of research on the effect of essential oils and ethanol extracts on the growth of mold fungi on Scots pine (Pinus sylvestris L.) wood. The analysis of fungal growth on the microbial medium showed that the degree of inhibition of microorganism growth depends on the amount of the extract added to the medium. At the same time, it was found that the highest dose of the extract, amounting to 5.0 cm³, almost completely inhibited the growth of fungi. In addition, it was found that mint ethanol extracts, the application of which in the wood is at least 40 g/m², have a fungistatic effect at the initial stage of fungal development. Solutions of essential oils turned out to be more active against fungi, although also in this case the desired biocidal effect was not achieved. Essential oils significantly slowed down the growth of the fungus Ch. globosum, with the strongest fungistatic effect found for ‘Morocco’ spearmint oil (Mentha spicata L.). Despite the fact that in tests on agar-maltose medium, the strongest biocidal activity against Ch. globosum was found for spearmint ‘Crispa’ (Mentha spicata L.) oil, the effect of growth inhibition was not so clearly visible in studies on wood. Essential oils applied to the surface of the wood slowed down the growth of T. viride fungus, but not to the extent that it was found in the case of Ch. globosum. The qualitative and quantitative composition of substances belonging to the group of terpenes and their derivatives was characterized using the GCMS technique. It was shown that the ethanol extracts of mints were dominated by substances belonging to the oxygen-containing monoterpenoid and monoterpene groups. In terms of quality, the composition of essential oils turned out to be richer.