23 © Springer Nature Switzerland AG 2019 R. Naraian (ed.), Mycodegradation of Lignocelluloses, Fungal Biology, https://doi.org/10.1007/978-3-030-23834-6_2 Chapter 2 Fungal Biodiversity Producing Cellulase Involved in Effcient Cellulolysis Praveen Kumar Gupta, Shreya Choudhary, C. Chandrananthi, J. Sharon Eveline, and S. P. Sushmitha 1 Introduction Cellulases are a class of lignocellulolytic enzymes involved in converting cellulose into simple sugars. Lignocellulose constitutes 60% of the plant cell wall and is one of its major components. Lignocellulose comprises a family of lignin, hemicellu- loses, and cellulose which are sugar biopolymer and its derivative (Galbe and Zacchi 2012). Cellulase is a polymer chain of D-glucose as monomeric units. It is the most widely available organic polymer in the world having 4 × 10 10 tonnes produced every year (Coughlan 1985). Cellulases from microbial sources have become the main focus due to varied biotechnological applications. These are synthesized on cellulosic material by various fungal and bacterial sources (aerobic, anaerobic, mesophilic, or thermophilic) during their growth. Fungal cellulases are known to be simpler than their bacterial counterpart having two separate domains. The two sepa- rate domains are (1) catalytic domain and (2) cellulose-binding module (CBM), having approximately 35 amino acids (Carvalho et al. 2003). Cellulase is a 3-enzyme membered family each having a particular function. The members in this family are exo-(1,4)-β-d-glucanase which is responsible for attack- ing cellulose chain ends, endo-(1,4)-β-d-glucanase which acts on O-glycosidic bonds in a random order which gives different lengths of glucan chain. The third is β-glucosidases which produces cellulose by acting on β-cellobiose (Kuhad et al. 2011). The most widely used and studied microorganisms for cellulase production are Trichoderma, Aspergillus, Cellulomonas, Penicillium, Clostridium, etc. (Kuhad et al. 2011). P. K. Gupta (*) · S. Choudhary · C. Chandrananthi · J. Sharon Eveline · S. P. Sushmitha Department of Biotechnology, R.V College of Engineering, Bangalore, India e-mail: praveenkgupta@rvce.edu.in