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Fungal Enzymes and Their Role in Bioenergy Cristiane Sanchez Farinas and Fernanda Marisa da Cunha

12.1

Introduction

The use of enzymes in different industrial sectors as an alternative to conventional chemical processes is currently increasing as a result of the technico-economic and environmental advantages inherent to such biocatalysts. The use of enzymes can contribute to energy reduction because enzymes act under mild temperature and pressure conditions. Reduction of the downstream processing steps is expected as well, since the formation of undesirable byproducts is reduced due to the high selectivity and specificity of enzymes. Moreover, when the enzymes can be immobilized onto solid supports it is possible to reuse them, which can significantly contribute to the cost reduction of the overall process. These characteristics make the use of enzymes in different sectors very favorable in comparison to the use of chemical catalysts, including the bioenergy sector. Developments in the bioenergy sector have been focusing on the use of biotechnological routes employing enzymes such as amylases, cellulases, and lipases in the production process of bioethanol and biodiesel in an attempt to meet the growing demand of the biofuels industry in a sustainable way. The industrial use of amylolytic enzymes in the process for bioethanol production from amylaceous sources, such as corn, is a very well-established technology. However, to date the industrial use of cellulases and lipases for biofuels production is still under development, with only a few large-scale industrial plants in operation.

C.S. Farinas (&)
F.M. da Cunha Embrapa Instrumentation, Rua XV de Novembro 1452, São Carlos, SP 13560-970, Brazil e-mail: [email protected] C.S. Farinas Graduate Program of Chemical Engineering, Federal University of São Carlos, São Carlos, SP 13565-905, Brazil © Springer International Publishing Switzerland 2016 D. Purchase (ed.), Fungal Applications in Sustainable Environmental Biotechnology, Fungal Biology, DOI 10.1007/978-3-319-42852-9_12

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C.S. Farinas and F.M. da Cunha

Cellulolytic enzymes are used to hydrolyze the cellulose present in lignocellulosic materials, such as agroindustrial and forest residues, into glucose that can be converted via fermentation into bioethanol, the so-called cellulosic ethanol, or second generation (2G) ethanol. In the enzymatic conversion of lignocellulosic biomass, the carbohydrate structures are advantageously hydrolyzed into monomeric sugars and such process is being considered as a key technology in future biorefineries. On the other hand, lipases are the enzymes that catalyze the transesterification reaction of triacylglycerides into fatty acid alkyl esters, which constitute the biodiesel. The main advantage of the use of enzymatic route for biodiesel production is related to the wider variety of oils or fats, either vegetable or animal origin, virgin or recycled, that can be processed into biodiesel (Hasan et al. 2006; Singh and Mukhopadhyay 2012; Hwang et al. 2014). The