Current challenges on the production and use of cellulolytic enzymes in the hydrolysis of lignocellulosic biomass

Abstract

The second generation (2G) ethanol obtained from lignocellulosic biomass has been considered as a potential alternative source of energy for the transportation sector. However, the technologies to convert lignocellulose into fermentable sugars still face several challenges. One of the major challenges of this process is related to the cost of the cellulolytic enzymes. Thus, the development of bioprocesses for enzyme production and strategies to increase the final yield of the enzymatic hydrolysis reactions are required to ensure the economic feasibility of the biomass conversion process. In this review, it is discussed the progress related to fungal enzyme technology over the past few years with major emphasis on the biocatalysts needed for cellulose degradation as well as on cultivation strategies for the production of enzymes on-site. The potential of applying secretome analysis as a tool for the characterization of the enzymatic complexes and some limitations on the use of enzymatic cocktails in the saccharification step, such as the unproductive adsorption of enzymes onto lignin are also discussed in light of the recent literature.

Moving from residual lignocellulosic biomass into high‐value products: Outcomes from a long‐term international cooperation

“…Endoglucanase productivity was threefold higher when microbial growth was carried out under SeqF and compared to conventional SmF, suggesting the potential of this technique for on‐site enzyme production 60 . The SeqF showed significant improvement in results when compared with the conventional submerged processes of cellulase production, in particular for endoglucanase, in agitated flasks 30,61–66 and conventional stirred‐tank bioreactors and airlift type bioreactors 67,68 …”

Conversion of levulinic acid to valuable chemicals: a review

“…17 Compared with the above two pathways, hydrolysis technology can convert biomass into valuable chemicals under relatively mild conditions (<200°C), thus showing a significant advantage. 18 As shown in Fig. 1, 19 firstly, cellulose and hemicellulose in lignocellulose are separated from lignin by acid or enzyme catalysis technology, and then, cellulose and hemicellulose are decomposed into glucose, xylose, and other monosaccharide molecules.…”

β-Glucosidase production by Trichoderma reesei and Thermoascus aurantiacus by solid state cultivation and application of enzymatic cocktail for saccharification of sugarcane bagasse

“…The efficiency with which cellulose is hydrolyzed by enzymes depends on many factors, such as characteristics of the substrate and nature of the enzymatic systems. Recent research has focused on the optimization of the enzymatic profile employed in the process by using enzymatic cocktails as one of the factors to improve both the yield and the rate of enzymatic hydrolysis [10].…”

“…It is known that the complete degradation of complex molecules such as cellulose requires several enzymes acting together. The action of cellulolytic enzymes depends on at least three hydrolases: endoglucanase, exoglucanase, and β-glucosidase, with the last being essential to avoid an inhibitory effect of cellobiose [10]. Considering that different microorganisms synthetize a characteristic pool of enzymes even when cultivated using the same substrate and under the same conditions, the formulation of enzymatic cocktails obtained by mixing extracts produced by different microorganisms is an alternative to increase the efficiency of the enzymatic hydrolysis, since different enzymes can act synergistically [11].…”