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  • Phenolic compounds generated during biomass

    2021-06-18

    Phenolic compounds generated during GDC-0449 receptor pretreatment inhibit and/or deactivate cellulolytic/hemicellulolytic enzymes as well as the viability and fermentative capacity of yeast and bacteria [4], [5], [6], [7], [8], [9], [10], [11], [12], [13]. Phenolic compounds cause changes in protein conformation leading to enzyme inactivation, although the exact mechanisms of inhibition are not fully understood [7]. This paper provides significant experimental data that shows enzymes from C. cubensis:P. pinophilum are more tolerant to phenolic inhibitors than enzymes from Trichoderma reesei and Aspergillus niger, microorganisms that represent a major source of commercially available cellulases and hemicellulases [8], [9], [11], [12], [13]. Laccase is shown to play a role in protecting hemicellulases from the effects of lignin-derived phenols.
    Materials and methods
    Results and discussion
    Conclusions Phenols deactivated cellulolytic and hemicellulolytic enzymes from C. cubensis:P. pinophilum mixtures. Oligomeric phenol (tannic acid) caused greater deactivation than monomeric phenols tested at the same concentrations and had a major impact on decreasing enzyme activity, regardless of the source of the enzyme. Even though the observed deactivation effect of selected monomeric and oligomeric phenols was significant for most of the enzyme activities tested, with exception of β-mannosidase activity, cellulolytic enzymes in the mixture from C. cubensis:P. pinophilum were more resistant to deactivation than equivalent cellulolytic enzymes from T. reesei and A. niger and have commercial potential in this regard. The presence of laccase activity mitigated deactivation due to phenols on xylanase and other hemicellulases, thus helping these xylan hydrolyzing enzymes to display a tolerance to phenolic inhibitors/deactivating compounds.
    Author agreement
    Acknowledgments We thank Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the financial support and Conselho Nacional de Pesquisa e Desenvolvimento Tecnológico (CNPq) for providing scholarships. This work was also supported by Hatch Act 10677, 10646, Purdue University Agricultural Research Programs and the Department of Agricultural and Biological Engineering, and CAPES (PDSE – Process 000218/2014-06, Process 012981/2013-03), Brazil.
    Introduction Enzymes are macromolecular biological catalysts that accelerate or catalyze chemical reactions. Like all catalysts, enzymes increase the rate of a reaction by lowering its activation energy and are known to catalyze a wide range of biochemical reactions, not only in the food industry. They are used in numerous industrial productions, playing important roles in the fields of foods, feed, pharmaceuticals, dyes, water treatment, textiles, cosmetics, leather and biofuels, among others [1, 2]. In recent years, the industrial applications of enzymes have exploded. Compared with conventional procedures based on acid-base and high temperature, enzymatic hydrolysis offers high efficiency and specificity. In addition, enzymatic reactions can be carried out under milder conditions with less pollution and fewer by-products. Moreover, enzymes themselves are relatively nontoxic and can be modified by various means [3, 4]. A worldwide survey on the sales of enzymes ascribed 31% of sales to food enzymes, 6% to feed enzymes and the remaining to technical enzymes [5]. However, enzymes have a relatively low stability under extreme conditions and have an extravagant expense for commercial use. To overcome these drawbacks, there is great interest in enhancing enzyme activity, stability, re-usage capacity and enzymatic efficiency. Generally, the methods of promoting enzymatic reactions are focused on three aspects: enzyme modification, substrate pretreatment, and enhancement of enzyme-substrate combination. These improvements can be attained via chemical, physical and genetic methods. As shown in Table 1, there are various techniques available to improve enzyme characteristics. Among these methods, ultrasound is one of the most important techniques.