title: The combination of plant-expressed cellobiohydrolase and low dosages of cellulases for the hydrolysis of sugar cane bagasse.
abstract: BACKGROUND
  The expression of biomass-degrading enzymes (such as cellobiohydrolases) in transgenic plants has the potential to reduce the costs of biomass saccharification by providing a source of enzymes to supplement commercial cellulase mixtures. Cellobiohydrolases are the main enzymes in commercial cellulase mixtures. In the present study, a cellobiohydrolase was expressed in transgenic corn stover leaf and assessed as an additive for two commercial cellulase mixtures for the saccharification of pretreated sugar cane bagasse obtained by different processes.
  
  
  RESULTS
  Recombinant cellobiohydrolase in the senescent leaves of transgenic corn was extracted using a simple buffer with no concentration step. The extract significantly enhanced the performance of Celluclast 1.5 L (a commercial cellulase mixture) by up to fourfold on sugar cane bagasse pretreated at the pilot scale using a dilute sulfuric acid steam explosion process compared to the commercial cellulase mixture on its own. Also, the extracts were able to enhance the performance of Cellic CTec2 (a commercial cellulase mixture) up to fourfold on a range of residues from sugar cane bagasse pretreated at the laboratory (using acidified ethylene carbonate/ethylene glycol, 1-butyl-3-methylimidazolium chloride, and ball-milling) and pilot (dilute sodium hydroxide and glycerol/hydrochloric acid steam explosion) scales. We have demonstrated using tap water as a solvent (under conditions that mimic an industrial process) extraction of about 90% recombinant cellobiohydrolase from senescent, transgenic corn stover leaf that had minimal tissue disruption.
  
  
  CONCLUSIONS
  The accumulation of recombinant cellobiohydrolase in senescent, transgenic corn stover leaf is a viable strategy to reduce the saccharification cost associated with the production of fermentable sugars from pretreated biomass. We envisage an industrial-scale process in which transgenic plants provide both fibre and biomass-degrading enzymes for pretreatment and enzymatic hydrolysis, respectively.
authors.affiliation: Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia ; Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Harrison
authors.affiliation: Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia ; Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: Zhanying
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia ; Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: Kylie
authors.initials: K
authors.lastname: Shand
authors.affiliation: Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia ; Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: Barrie Fong
authors.initials: BF
authors.lastname: Chong
authors.affiliation: Syngenta Biotechnology Inc., Research Triangle Park, 3054 East Cornwallis Road, Durham, NC 27709-2257 USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Nichols
authors.affiliation: Syngenta Biotechnology Inc., Research Triangle Park, 3054 East Cornwallis Road, Durham, NC 27709-2257 USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Oeller
authors.affiliation: Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia ; Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: Ian M
authors.initials: IM
authors.lastname: O'Hara
authors.affiliation: Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: William Os
authors.initials: WO
authors.lastname: Doherty
authors.affiliation: Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia ; Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: James L
authors.initials: JL
authors.lastname: Dale
keywords: Biomass; Cellobiohydrolase; Cellulase; Enzymatic hydrolysis; Pretreatment; Saccharification; Sugar cane; Transgenic