CHAPTER FOUR Carbohydrate-Binding Modules of Fungal Cellulases: Occurrence in Nature, Function, and Relevance in Industrial Biomass Conversion Anikó Várnai * , Miia R. Mäkelä † , Demi T. Djajadi † , Jenni Rahikainen { , Annele Hatakka † , Liisa Viikari †,1 * Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway † Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland { VTT, Technical Research Centre of Finland, Espoo, Finland 1 Corresponding author: e-mail address: liisa.viikari@helsinki.fi Contents 1. Introduction 104 2. Cellulolytic Enzymes 107 2.1 Fungal cellulolytic enzymes 109 2.2 Structures of fungal cellulases 117 2.3 Occurrence of CBMs 119 2.4 Function of CBMs in fungal enzyme–substrate interaction 128 2.5 Cellulose degradation and occurrence of CBMs in the genomes of selected fungi 138 3. Enzymatic Biomass Hydrolysis 140 3.1 Conversion processes 140 3.2 Enzymes required for total hydrolysis of lignocellulose 141 3.3 Lignin in biomass degradation 143 3.4 Hydrolysis at high substrate concentration 144 3.5 Cellulases with and without CBM in high DM hydrolysis 145 3.6 Desorption of enzymes 147 3.7 Recovery of non-CBM enzymes 148 3.8 Recyclability of enzymes 150 4. Conclusions 152 References 153 Abstract In this review, the present knowledge on the occurrence of cellulases, with a special emphasis on the presence of carbohydrate-binding modules (CBMs) in various fungal strains, has been summarized. The importance of efficient fungal cellulases is growing Advances in Applied Microbiology, Volume 88 # 2014 Elsevier Inc. ISSN 0065-2164 All rights reserved. http://dx.doi.org/10.1016/B978-0-12-800260-5.00004-8 103