Monday, April 19, 2010 - 2:00 PM
2-03
The significance of supramolecular structures of cellulose for the enzymatic hydrolysis of plant cell walls
Lisbeth Thygesen1, Budi Juliman Hidayat1, Katja Salomon Johansen2, and Claus Felby1. (1) Danish Center for Forest and Landscape, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 23, DK-1958 Frederiksberg C, Denmark, (2) Novozymes A/S, Krogshøjvej 36, DK-2880 Bagsværd, Denmark
The study of the deconstruction of biomass by enzymatic hydrolysis has hitherto not focussed on the importance of supramolecular structures of cellulose. In cellulose or lignocellulose fibers, regions with a different organisation of the microfibrils can be found. These regions are called dislocations and they are known to be more susceptible to various forms of degradation (Nyholm et al. 2001). Dislocations can be introduced by mechanical forces (Terziev et al. 2005, Eder et al. 2008) but are also present already in the growing plant (Thygesen and Asgharipour 2008). Traditionally the cellulose within these regions has been assumed to be amorphous, but as we will show they are birefringent, thus they have a crystalline organisation. Their exact structure remains unknown but results indicating their crystalline organisation will be presented.
Dislocations may be entry points for endoglucanases. Using fluorescent labelled enzymes combined with confocal fluorescence microscopy we show how some endoglucanases selectively bind to dislocations during the initial phase of the hydrolysis. Also we have found that using a commercial cellulase mixture on hydrothermally treated wheat straw, the fibers are cut into segments corresponding to the sections between the dislocations initially present. Interestingly, a similar mechanism has previously been observed for acid hydrolysis of other natural fibers (Ander et al. 2005, Thygesen 2008).
Our results indicate that dislocations are important during the initial part of enzymatic hydrolysis of cellulose. The implications of this phenomenon have not yet been recognized or explored within cellulosic biofuels.
Dislocations may be entry points for endoglucanases. Using fluorescent labelled enzymes combined with confocal fluorescence microscopy we show how some endoglucanases selectively bind to dislocations during the initial phase of the hydrolysis. Also we have found that using a commercial cellulase mixture on hydrothermally treated wheat straw, the fibers are cut into segments corresponding to the sections between the dislocations initially present. Interestingly, a similar mechanism has previously been observed for acid hydrolysis of other natural fibers (Ander et al. 2005, Thygesen 2008).
Our results indicate that dislocations are important during the initial part of enzymatic hydrolysis of cellulose. The implications of this phenomenon have not yet been recognized or explored within cellulosic biofuels.
References
Ander P, Daniel G, Garcia-Luindgren C, Marklund A Nord Pulp Pap Res J (2005) 20:84
Eder M, Terziev N, Daniel G, Burgert I Holzforschung (2008) 62:77
Nyholm K, Ander P, Bardage S, Daniel G Nord Pulp Pap Res J (2001) 4:374
Terziev N, Daniel G, Marklund A Holzforschung (2005) 59:163
Thygesen LG J Mater Sci (2008) 43:1311
Thygesen LG, Asgharipour MR J Mater Sci (2008) 43:3670
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See more of The 32nd Symposium on Biotechnology for Fuels and Chemicals (April 19-22, 2010)
See more of General Submissions
See more of The 32nd Symposium on Biotechnology for Fuels and Chemicals (April 19-22, 2010)