Biological pretreatment with a cellobiose dehydrogenase-deficient strain of Trametes versicolor enhances the biofuel potential of canola straw Thomas Canam a,1 , Jennifer R. Town a , Adrian Tsang b , Tim A. McAllister c , Tim J. Dumonceaux a,⇑ a Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, Canada S7N 0X2 b Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montréal, PQ, Canada H4B 1R6 c Lethbridge Research Centre, Agriculture and Agri-Food Canada, 5403 1[st] Avenue South, Lethbridge, AB, Canada T1J 4B1 article info Article history: Received 24 June 2011 Received in revised form 8 August 2011 Accepted 10 August 2011 Available online 17 August 2011 Keywords: Biological pretreatment Canola straw Cellobiose dehydrogenase Lignocellulose Trametes versicolor abstract The use of Trametes versicolor as a biological pretreatment for canola straw was explored in the context of biofuel production. Specifically, the effects on the straw of a wild-type strain (52 J) and a cellobiose dehy- drogenase (CDH)-deficient strain (m4D) were investigated. The xylose and glucose contents of the straw treated with 52 J were significantly reduced, while only the xylose content was reduced with m4D treat- ment. Lignin extractability was greatly improved with fungal treatments compared to untreated straw. Saccharification of the residue of the m4D-treated straw led to a significant increase in proportional glu- cose yield, which was partially attributed to the lack of cellulose catabolism by m4D. Overall, the results of this study indicate that CDH facilitates cellulose access by T. versicolor. Furthermore, treatment of lig- nocellulosic material with m4D offers improvements in lignin extractability and saccharification efficacy compared to untreated biomass without loss of substrate due to fungal catabolism. Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved. 1. Introduction The cost associated with chemical, thermal and mechanical pre- treatment of plant biomass destined for biofuel and biomaterial production impinges on the overall energy balance of these pro- cesses, thereby decreasing the market competitiveness of the prod- ucts. These energy intensive pretreatments typically focus on the fractionation of one or more of the major components of plant bio- mass to enhance the efficiency of downstream processing (Chandra et al., 2007; Hendriks and Zeeman, 2009). As a result, alternative strategies for more cost-effective fractionation of lignocellulose are key for sustainable biofuel and biomaterial production. Biological pretreatments have the potential to mitigate some of the costs associated with current biomass pretreatment strategies by taking advantage of the innate ability of certain microbial spe- cies to selectively deconstruct the various components of lignocel- lulose (Anderson and Akin, 2008). As a consequence, identifying organisms capable of processing recalcitrant biomass has been the focus of recent research initiatives. For example, an investiga- tion of the metatranscriptome of the muskoxen rumen illuminated the breadth of both the genomic and transcriptomic diversity associated with lignocellulosic decomposition (Qi et al., in press). Similarly, exploration of cow rumen digestion of switchgrass re- vealed a plethora of microbiota associated with the expression of over 27,000 putative lignocellulose-modifying enzymes (Hess et al., 2011). The results of these studies and others of this nature will undoubtedly identify organisms and enzymes that will en- hance future industrial biomass conversion strategies. In addition to recent microbial community analyses, there has been renewed interest in several well-known microbial species due to their ability to deconstruct recalcitrant biomass. Of particu- lar interest are white-rot and brown-rot fungi, which specialize in lignocellulose depolymerization. This unique ability has provided the impetus for genomic, secretomic and transcriptomic analyses of notable lignocellulose-degrading fungi, such as Postia placenta (Martinez et al., 2009), Phanerochaete chrysosporium (Sato et al., 2009; Vanden Wymelenberg et al., 2009), and Phanerochaete carn- osa (MacDonald et al., 2011). Due to our increasing understanding of the mechanisms underpinning their unique ability to decom- pose lignocellulose, these organisms have the potential to be effec- tive low-cost biomass pretreatment agents. To this end, a number of studies have investigated the efficacy of white rot fungi with re- spect to biological pretreatment of lignocellulosic material includ- ing wheat and rice straw, switchgrass and corn stover (Anderson and Akin, 2008; Patel et al., 2007; Talebnia et al., 2010; Wan and Li, 2010). The high residue production of canola makes it an attrac- tive substrate for biofuel production, although its composition lim- its the amount of fermentable glucose available using standard alkali or acid pretreatments (George et al., 2010). Although 0960-8524/$ - see front matter Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2011.08.045 ⇑ Corresponding author. Tel.: +1 306 956 7653; fax: +1 306 956 7247. E-mail address: tim.dumonceaux@agr.gc.ca (T.J. Dumonceaux). 1 Present address: Department of Biological Sciences, Eastern Illinois University, 600 Lincoln Avenue, Charleston, IL 61920, USA. Bioresource Technology 102 (2011) 10020–10027 Contents lists available at SciVerse ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech