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Abstract:The continuous increase in the world energy and chemicals demand requires the development of sustainable alternatives to non-renewable sources of energy. Biomass facilities and biorefineries represent interesting options to gradually replace the present industry based on fossil fuels. Lignocellulose is the most promising feedstock to be used in biorefineries. From a sugar platform perspective, a wide range of fuels and chemicals can be obtained via microbial fermentation processes, being ethanol the most significant lignocellulose-derived fuel. Before fermentation, lignocellulose must be pretreated to overcome its inherent recalcitrant structure and obtain the fermentable sugars. Usually, harsh conditions are required for pretreatment of lignocellulose, producing biomass degradation and releasing different compounds that are inhibitors of the hydrolytic enzymes and fermenting microorganisms. Moreover, the lignin polymer that remains in pretreated materials also affects biomass conversion by limiting the enzymatic hydrolysis. The use of laccases has been considered as a very powerful tool for delignification and detoxification of pretreated lignocellulosic materials, boosting subsequent saccharification and fermentation processes. This review compiles the latest studies about the application of laccases as useful and environmentally friendly delignification and detoxification technology, highlighting the main challenges and possible ways to make possible the integration of these enzymes in future lignocellulose-based industries.

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The dielectric functions of Cu 2 ZnGeS 4 bulk crystals grown by the Bridgman method were measured over the energy range 1.4 to 4.7 eV at room temperature using variable angle spectroscopic ellipsometry. The observed structures in the dielectric functions were adjusted using the Adachi's model and attributed to interband transitions E 0 , E 1A , and E 1B at ⌫:͑000͒, N͑A͒ :2 / a͑0.5 0.5 0.5͒, and T͑Z͒ :2 / a͑0 0 0.5͒ points of the first Brillouin zone, respectively. The model parameters ͑threshold energy, strength, and broadening͒ have been determined using the simulated annealing algorithm. The decrease in the first gap, E 0 , has been attributed to a higher Ge-S hybridization. The spectral dependence of the complex refractive index, the absorption coefficient, and the normal-incidence reflectivity were also derived.

This work describes the solid-state fermentation (SSF) of wheat straw with Streptomyces sp. MDG147 and further soda-pulping process to obtain wheat straw soda lignins (WSLs). Subsequently, these WSLs were NCO-functionalized with 1,6-hexamethylene diisocyanate and then dispersed in castor oil to achieve stable oleogels. The WSLs were characterized using standard analytical methods, gel permeation chromatography, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Rheological properties of oleogels were determined by means of small-amplitude oscillatory shear and viscous flow measurements. The enzymatic profile and production of lignin−carbohydrate complexes were recorded along the growth time of Streptomyces, whose life cycle was achieved after 7 days. NCO-functionalized WSL was able to chemically interact with castor oil via urethane bonding, providing oleogels with suitable rheological characteristics. Linear viscoelastic functions and viscosity values of oleogels were higher when wheat straw was submitted to SSF using Streptomyces, turning out in stronger oleogels.

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Lignin-rich residues from the cellulose-based industry are traditionally incinerated for internal energy use. The future biorefineries that convert cellulosic biomass into biofuels will generate more lignin than necessary for internal energy use, and therefore value-added products from lignin could be produced. In this context, a good understanding of lignin is necessary prior to its valorization. The present study focused on the characterization of lignin-rich residues from biochemical ethanol production, including steam explosion, saccharification, and fermentation, of wheat straw and olive tree pruning. In addition to the composition and purity, the lignin structures (S/G ratio, interunit linkages) were investigated by spectroscopy techniques such as FTIR and 2D-NMR. Together with the high lignin content, both residues contained significant amounts of carbohydrates, mainly glucose and protein. Wheat straw lignin showed a very low S/G ratio associated withp-hydroxycinnamates (p-coumarate and ferulate), whereas a strong predominance of S over G units was observed for olive tree pruning lignin. The main interunit linkages present in both lignins wereβ-O-4′ethers followed by resinols and phenylcoumarans. These structural characteristics determine the use of these lignins in respect to their valorization.

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