title: Pretreatment of microcrystalline cellulose in organic electrolyte solutions for enzymatic hydrolysis.
abstract: BACKGROUND
  Previous studies have shown that the crystalline structure of cellulose is negatively correlated with enzymatic digestibility, therefore, pretreatment is required to break down the highly ordered crystalline structure in cellulose, and to increase the porosity of its surface. In the present study, an organic electrolyte solution (OES) composed of an ionic liquid (1-allyl-3-methylimidazolium chloride ([AMIM]Cl)) and an organic solvent (dimethyl sulfoxide; DMSO) was prepared, and used to pretreat microcrystalline cellulose for subsequent enzymatic hydrolysis; to our knowledge, this is the first time that this method has been used.
  
  
  RESULTS
  Microcrystalline cellulose (5 wt%) rapidly dispersed and then completely dissolved in an OES with a molar fraction of [AMIM]Cl per OES (χ [AMIM]Cl) of greater than or equal to 0.2 at 110°C within 10 minutes. The cellulose was regenerated from the OES by precipitation with hot water, and enzymatically hydrolyzed. As the χ [AMIM]Cl of the OES increased from 0.1 to 0.9, both the hydrolysis yield and initial hydrolysis rate of the regenerated cellulose also increased gradually. After treatment using OES with χ [AMIM]Cl of 0.7, the glucose yield (54.1%) was 7.2 times that of untreated cellulose. This promotion of hydrolysis yield was mainly due to the decrease in the degree of crystallinity (that is, the crystallinity index of cellulose I).
  
  
  CONCLUSIONS
  An OES of [AMIM]Cl and DMSO with χ [AMIM]Cl of 0.7 was chosen for cellulose pretreatment because it dissolved cellulose rapidly to achieve a high glucose yield (54.1%), which was only slightly lower than the value (59.6%) obtained using pure [AMIM]Cl. OES pretreatment is a cost-effective and environmentally friendly technique for hydrolysis, because it 1) uses the less expensive OES instead of pure ionic liquids, 2) shortens dissolution time, 3) requires lower energy for stirring and transporting, and 4) is recyclable.
authors.affiliation: Chinese Academy of Sciences, Biomass Group, Laboratory of Tropical Plant Resource Science, Xishuangbanna Tropical Botanical Garden, 88 Xuefulu, Kunming, Yunnan Province, 650223, China. zhenfang@xtbg.ac.cn.
authors.forename: Xiao-Fei
authors.initials: XF
authors.lastname: Tian
authors.forename: Zhen
authors.initials: Z
authors.lastname: Fang
authors.forename: Dan
authors.initials: D
authors.lastname: Jiang
authors.forename: Xi-Yan
authors.initials: XY
authors.lastname: Sun
references.citation: Appl Microbiol Biotechnol. 2010 Jun;87(1):117-26
references.pmid: 20182710
references.citation: Biotechnol Bioeng. 2011 Mar;108(3):511-20
references.pmid: 21246505
references.citation: Bioresour Technol. 2009 Jul;100(14):3570-5
references.pmid: 19329299
references.citation: Adv Biochem Eng Biotechnol. 2007;108:41-65
references.pmid: 17646946
references.citation: Curr Opin Chem Biol. 2006 Apr;10(2):141-6
references.pmid: 16522374
references.citation: Bioresour Technol. 2009 May;100(9):2580-7
references.pmid: 19157872
references.citation: Bioresour Technol. 2005 Apr;96(6):673-86
references.pmid: 15588770
references.citation: J Agric Food Chem. 2007 Oct 31;55(22):9142-8
references.pmid: 17907779
references.citation: J Am Chem Soc. 2004 Nov 10;126(44):14350-1
references.pmid: 15521743
references.citation: Biomacromolecules. 2005 May-Jun;6(3):1510-5
references.pmid: 15877372
references.citation: Chem Rev. 2009 Dec;109(12):6712-28
references.pmid: 19757807
references.citation: Bioresour Technol. 2011 Jan;102(2):1214-9
references.pmid: 20728347
references.citation: Biotechnol Bioeng. 2011 Jun;108(6):1229-45
references.pmid: 21337342
references.citation: J Am Chem Soc. 2002 May 8;124(18):4974-5
references.pmid: 11982358
references.citation: Chem Commun (Camb). 2011 Jan 7;47(1):511-3
references.pmid: 20972501
references.citation: Bioresour Technol. 2009 Jan;100(1):10-8
references.pmid: 18599291
references.citation: Langmuir. 2007 Dec 4;23(25):12535-40
references.pmid: 17988165
references.citation: Biotechnol Bioeng. 2006 Dec 5;95(5):904-10
references.pmid: 16917949
references.citation: Biotechnol Bioeng. 1983 Aug;25(8):2041-53
references.pmid: 18551549
references.citation: Bioresour Technol. 2005 Dec;96(18):1978-85
references.pmid: 16112485
references.citation: Biotechnol Bioeng. 1983 Jan;25(1):157-72
references.pmid: 18548545
references.citation: Biomacromolecules. 2004 Mar-Apr;5(2):266-8
references.pmid: 15002983