Production of hydrolytic enzymes from aspergillus niger in solid-state fermentation and their subsequent application on lignocellulosic residues pretreated with deep eutectic solvents to obtain fermentable sugars

Resumo

Agro-industrial residues are mostly used for composting or discarded directly in the field, resulting in the proliferation of pollutants and toxic emissions into the environment. However, these residues are mainly composed of cellulose, hemicellulose, and lignin, chemical components that can be employed to generate many products with high added value. Therefore, it is necessary to develop adequate processes to transform the lignocellulosic biomass into a source of wealth, renewable, abundant, and economical. According to the concept of a biorefinery, lignocellulosic biomass can be fractioned into its main compounds due to the application of physical, chemical, and biological pretreatments to generate solutions of fermentable sugars. However, the high costs of enzymes and their availability continue to be the bottleneck to implement this technology. In consequence, the industry demands more stable, active, and economical enzymatic catalysts. Hence, studies have been carried out to produce enzymes from different residues, mechanisms of action, regulation of expression in microorganisms, and strategies to make the process more economically viable. Among the microorganisms that degrade the lignocellulosic complex, due to the production of hydrolytic enzymes, are filamentous fungi, known as agents of decomposition of organic matter. Likewise, the use of chemical pretreatments that facilitate the digestion of lignocellulose, require less energy to perform the process, generate less secondary toxic waste, and be economical, replicable, and scalable. The recent use of deep eutectic solvents (DES) is highlighted, due to the ability to form eutectic mixtures and have advantages over conventional processes, since they are biodegradable and inexpensive, which makes them attractive for application and scaling in industries to obtain a variety of products. For this reason, this work proposes the study of the mechanism of production of hydrolytic enzymes from a variety of fungi of the genus Asperguillus employed solid-state fermentation and on the other hand, the delignification of the lignocellulosic biomass employing deep eutectic solvents (DES) and finally, the application of the hydrolytic enzymes produced on the delignified materials for the fractionation of residual cellulose and hemicellulose in order to obtain solutions of fermentable sugars.