title: The synergistic action of accessory enzymes enhances the hydrolytic potential of a "cellulase mixture" but is highly substrate specific.
abstract: BACKGROUND
  Currently, the amount of protein/enzyme required to achieve effective cellulose hydrolysis is still too high. One way to reduce the amount of protein/enzyme required is to formulate a more efficient enzyme cocktail by adding so-called accessory enzymes such as xylanase, lytic polysaccharide monooxygenase (AA9, formerly known as GH61), etc., to the cellulase mixture. Previous work has shown the strong synergism that can occur between cellulase and xylanase mixtures during the hydrolysis of steam pretreated corn stover, requiring lower protein loading to achieve effective hydrolysis. However, relatively high loadings of xylanases were required. When family 10 and 11 endo-xylanases and family 5 xyloglucanase were supplemented to a commercial cellulase mixture varying degrees of improved hydrolysis over a range of pretreated, lignocellulosic substrates were observed.
  
  
  RESULTS
  The potential synergistic interactions between cellulase monocomponents and hemicellulases from family 10 and 11 endo-xylanases (GH10 EX and GH11 EX) and family 5 xyloglucanase (GH5 XG), during hydrolysis of various steam pretreated lignocellulosic substrates, were assessed. It was apparent that the hydrolytic activity of cellulase monocomponents was enhanced by the addition of accessory enzymes although the "boosting" effect was highly substrate specific. The GH10 EX and GH5 XG both exhibited broad substrate specificity and showed strong synergistic interaction with the cellulases when added individually. The GH10 EX was more effective on steam pretreated agriculture residues and hardwood substrates whereas GH5 XG addition was more effective on softwood substrates. The synergistic interaction between GH10 EX and GH5 XG when added together further enhanced the hydrolytic activity of the cellulase enzymes over a range of pretreated lignocellulosic substrates. GH10 EX addition could also stimulate further cellulose hydrolysis when added to the hydrolysis reactions when the rate of hydrolysis had levelled off.
  
  
  CONCLUSIONS
  Endo-xylanases and xyloglucanases interacted synergistically with cellulases to improve the hydrolysis of a range of pretreated lignocellulosic substrates. However, the extent of improved hydrolysis was highly substrate dependent. It appears that those accessory enzymes, such as GH10 EX and GH5 XG, with broader substrate specificities promoted the greatest improvements in the hydrolytic performance of the cellulase mixture on all of the pretreated biomass substrates.
authors.affiliation: Forestry Products Biotechnology/Bioenergy Group, Wood Science Department, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada. jack.saddler@ubc.ca.
authors.forename: Jinguang
authors.initials: J
authors.lastname: Hu
authors.forename: Valdeir
authors.initials: V
authors.lastname: Arantes
authors.forename: Amadeus
authors.initials: A
authors.lastname: Pribowo
authors.forename: Jack N
authors.initials: JN
authors.lastname: Saddler
references.citation: Bioresour Technol. 2011 Oct;102(19):9090-5
references.pmid: 21767947
references.citation: Biotechnol Biofuels. 2011 May 18;4:12
references.pmid: 21592333
references.citation: Eur J Biochem. 1991 Aug 15;200(1):157-63
references.pmid: 1879420
references.citation: Biotechnol Bioeng. 1998 Sep 5;59(5):621-34
references.pmid: 10099380
references.citation: Biotechnol Bioeng. 1999 Aug 5;64(3):284-9
references.pmid: 10397865
references.citation: Crit Rev Biotechnol. 2010 Sep;30(3):176-91
references.pmid: 20225927
references.citation: Science. 2011 Sep 2;333(6047):1279-82
references.pmid: 21885779
references.citation: J Mol Biol. 1997 Sep 26;272(3):383-97
references.pmid: 9325098
references.citation: Biotechnol Bioeng. 2011 Oct;108(10):2300-11
references.pmid: 21520024
references.citation: Anal Biochem. 2001 May 1;292(1):125-9
references.pmid: 11319826
references.citation: Biotechnol Biofuels. 2011 Sep 07;4:29
references.pmid: 21899748
references.citation: J Biotechnol. 2006 Feb 10;121(3):338-45
references.pmid: 16157409
references.citation: Appl Biochem Biotechnol. 2010 Nov;162(6):1737-50
references.pmid: 20407843
references.citation: Microbiol Rev. 1988 Sep;52(3):305-17
references.pmid: 3141761
references.citation: mBio. 2012 Dec 11;3(6):
references.pmid: 23232718
references.citation: Biotechnol Bioeng. 2006 Apr 5;93(5):880-6
references.pmid: 16345088
references.citation: Biotechnol Biofuels. 2011 Oct 05;4:36
references.pmid: 21974832
references.citation: Mol Plant. 2009 Sep;2(5):904-9
references.pmid: 19825667
references.citation: Biotechnol Prog. 2009 Mar-Apr;25(2):315-22
references.pmid: 19266561
references.citation: J Biol Chem. 2004 Mar 5;279(10):9597-605
references.pmid: 14668328
references.citation: J Biol Chem. 2004 Aug 20;279(34):36029-37
references.pmid: 15181003
references.citation: Appl Biochem Biotechnol. 2003 Spring;105 -108:319-35
references.pmid: 12721456
references.citation: Appl Environ Microbiol. 1996 Sep;62(9):3165-70
references.pmid: 8795205
references.citation: Crit Rev Biotechnol. 2002;22(1):33-64
references.pmid: 11958335
references.citation: Biotechnol Biofuels. 2011 Feb 10;4:3
references.pmid: 21310050
references.citation: Mol Plant. 2011 Jan;4(1):17-24
references.pmid: 20943810
references.citation: Biochemistry (Mosc). 2002 Aug;67(8):850-71
references.pmid: 12223085
references.citation: Biotechnol Biofuels. 2013 May 20;6(1):80
references.pmid: 23687947
references.citation: Bioresour Technol. 2010 Apr;101(8):2770-81
references.pmid: 19948399
references.citation: J Agric Food Chem. 2010 Nov 10;58(21):11294-301
references.pmid: 20942461
references.citation: Plant J. 2004 Apr;38(1):27-37
references.pmid: 15053757
references.citation: Biotechnol Biofuels. 2011 Jun 24;4(1):18
references.pmid: 21702938
references.citation: Bioresour Technol. 2007 Sep;98(13):2503-10
references.pmid: 17113771
references.citation: Plant Physiol. 1995 Aug;108(4):1579-85
references.pmid: 7659752
references.citation: Biotechnol Biofuels. 2010 Feb 23;3:4
references.pmid: 20178562
references.citation: Microb Cell Fact. 2011 Feb 11;10:8
references.pmid: 21314954
references.citation: Can J Microbiol. 2004 Oct;50(10):835-43
references.pmid: 15644898
references.citation: Bioresour Technol. 2008 Oct;99(15):6826-33
references.pmid: 18331790
references.citation: Protein Expr Purif. 2005 Jul;42(1):122-30
references.pmid: 15939297
references.citation: Bioresour Technol. 2010 Dec;101(23):9097-105
references.pmid: 20678930
references.citation: Biotechnol Biofuels. 2011 Feb 22;4:5
references.pmid: 21342516
references.citation: Bioresour Technol. 2010 Dec;101(24):9624-30
references.pmid: 20708404
references.citation: Nat Biotechnol. 2008 May;26(5):553-60
references.pmid: 18454138
references.citation: J Ind Microbiol Biotechnol. 2003 May;30(5):279-91
references.pmid: 12698321
references.citation: FEMS Microbiol Rev. 2005 Jan;29(1):3-23
references.pmid: 15652973
references.citation: Biotechnol Prog. 2007 Nov-Dec;23(6):1270-6
references.pmid: 18062669
references.citation: Carbohydr Res. 2004 Oct 20;339(15):2529-40
references.pmid: 15476714
references.citation: FEMS Microbiol Lett. 1991 Nov 15;68(2):197-203
references.pmid: 1778443
references.citation: Biochemistry. 2010 Apr 20;49(15):3305-16
references.pmid: 20230050
references.citation: Bioresour Technol. 2010 Oct;101(20):7827-33
references.pmid: 20570139
references.citation: Biotechnol Bioeng. 2006 Aug 20;94(6):1122-8
references.pmid: 16732604